Uninterruptible power supplies from APC are very reliable, but, like all household uninterruptible power supplies, they have a short operating time at normal load - 10-20 minutes. Therefore, it was decided to increase the capacity of the battery used in the UPS by replacing it with a car one.

The one that had served faithfully for three years was used as an uninterruptible power supply.

The operating voltage of the battery in this uninterruptible power supply is 24 volts, so it is necessary to use two 12 volt batteries from the car. The most inexpensive car batteries in terms of price/power ratio available on the market were taken - Tyumen 6ST60-AP3.

The standard battery, consisting of two batteries, was removed from the UPS case and thick three-core copper wires with a cross-section of 4 squares were connected instead. A large cross-section of the wire is necessary, because the current from the batteries to the uninterruptible power supply can reach 100 amperes and thinner wires will heat up and can melt the insulation. The wire was routed through a specially sawn hole in the front panel.

The wire was connected to the batteries using standard automotive terminals. The batteries are connected in series to each other using a short piece of the same wire. When connecting batteries to a UPS, you must strictly observe the polarity and not confuse plus with minus, which can lead to failure of the entire structure.

Uninterruptible power supplies are not designed to operate for many hours, so for additional cooling, two 12-volt computer fans were attached to the holes on the side surfaces of the case, connected in series to obtain a supply voltage of 24 volts. The air flow direction was chosen to be multidirectional - one fan blows inside the UPS case, the second outside. The fans are connected to wires coming from the UPS to the batteries.

The voltage on fully charged batteries in standby mode is 27.54 volts according to the readings of the APC program and 27.6 volts according to the voltmeter readings at the terminals. The voltage is divided equally between both batteries and one battery accounts for 13.8 volts. This is a good value for a car battery, which can last a very long time in such conditions.

After a couple of charge-discharge cycles, the uninterruptible power supply was recalibrated, which showed an operating time of more than 7 hours (434 minutes) at a load of 200 watts ( system unit, hub and WiFi hotspot access).

Guys, I want to use this circuit to get a 220 volt socket in my car (convenient for traveling). Has anyone tried this?

UPS are designed to operate from a 220V network and in the event of an emergency power outage, they immediately switch to battery operation mode.

In your case, it is much easier to purchase a car inverter.

Good day.

There are a number of APC SMART UPS 1000 and 1500 available.

Question about choosing batteries, GEL or AGM? I would like to avoid fumes...

I have a UPS Mercury 600. Is it possible to install one battery? to 12 volts in order to increase the operating time from UPSa

Good day.

Which UPS is better for the car battery APC Back-Up CS 500 or APC Back BK650MI 650VA.

I have the same UPS, and I have a question: when calibrating the battery, it shows that the batteries are bad, when the voltage on them is 24 volts. How can I change this shutdown threshold? Car batteries allow a drawdown of 10.5 volts under load, but here it’s 12 and that’s it, it goes out (((Are there any options?

http://www.apc-fix.com/ this one is better http://saprjkin.narod.ru/upsdiag.htm I also revived dead firmware... in general, 2 hundred parts of atlases have been working for a year on the smart i1000, installed an additional fan, charging time is 15-20 hours from the UPS I don’t regret that I bought it, by the way, about 5 minutes ago the electricity was turned off, I’m sitting here writing, I remembered this page... The computer is true with built-in video + a server 2 processor third stump with 2 gigabytes of insanity and 2 screws. I didn’t check the modem with the switch for 8-9 hours of operation anymore.

Worked for 4 hours without power...

I will share my experience:

There was a UPC APC 500 CS. I made it into a charger for a car battery (60A/h), saved it several times, because... I haven’t gotten my hands on a regular charger for a car battery yet, but there are a bunch of UPS ones.

The same goal was to obtain 220 volts from 12 for charging photos, videos, and other low-power gadgets.

To do this, I had to do some magic with the back wall of the UPS, and more specifically with the connectors, in order to do everything civilly and not drill into the case: I soldered the wires from the standard battery to a “MALE” type connector, which previously served to output 220 volts from the UPS, which was also The same cable that powered the devices from the UPS was modified, and more specifically, the “MALE” type plug was cut off, and multi-colored “crocodiles” were soldered, observing the polarity (Red - Plus, black - Minus). The cable was chosen to be as thick as possible from those that were available.

Then I bought myself an inverter, which takes up little space and is more aesthetically pleasing. And the modified UPS lies in the garage, and sometimes helps out.

Good afternoon, everyone, I came across this oops http://evrokom.com/UPS500VABackMiAPCBK500MII_3056.html tell me why, when connecting a 42-inch LSD TV, the consumption should be around 100 watts and the oops knocks it out? and tell me, when connecting a more capacious battery to it, does it also need to be calibrated somehow?

ippon smart winner 1000 is not bad either, the price is 6000 rubles, pure sine. minus the weak charge current - 0.5A - that is, powering about 5% off-line is only possible, and the pluses are the price and low charge current) the battery will not boil.

Today in our laboratory we are testing UPS under the brand name. This company is unusually modest in describing its history, but does not hesitate to declare its achievements, we quote: " Innovative technologies and developments have allowed KRAULER to achieve absolute superiority in the field of new technologies". A small but effective journalistic investigation revealed the real manufacturer of these UPSs. The Chinese company has been producing UPSs, inverters, chargers and voltage stabilizers since 1984. The products of this company, in relation to UPSs, have their own “face”. Elegant cases with blue displays look very nice. We will try to find out what is hidden behind the external attractiveness using the example of the UPS model KRAULER UP-D650VA. Description

The UPS under test is a typical representative of line-interactive UPSs with a display. A total of eight models of similar design are available, ranging from 400 to 2000 VA. All KRAULER UPSs produce an approximate sine wave.

Our copy arrived for testing without instructions, so specifications were taken from the company website:

Input voltage, frequency	165-275 V without switching to batteries
Output (when operating on batteries) voltage, frequency	220 V ±10% / 50 Hz
Automatic voltage regulator
output power	650 VA / 400 Watt
Output waveform	approximated sinusoid
Time battery life	up to 15 minutes
Function to start equipment without connecting to the mains
Battery type, voltage and capacity	12V 7Ah - Maintenance-free sealed lead-acid battery with thickened electrolyte
Time to charge batteries to 90% after discharging to load cut-off level under full load.
Indicators	LCD display
Sound alarm	Signal for switching to battery mode, special signal for low battery charge, overload signal.
Self-diagnosis	when turned on and controlled by software
Overload protection when operating from the network	No clear data
Data line protection	Telephony protection
Interface
Monitoring	Software power management
Dimensions W×D×H	85×330×150 mm
Output connectors

The UPS is delivered in a cardboard box, decorated in strict corporate style. For ease of transportation, the box is equipped with a plastic handle. Judging by the sticker on the box, the tested UPS was made in China.

Our sample package included:

• interface cable for communication with PC USB
• RJ-11 telephone cable 2 pieces
• load connection cable
• cable for connecting to the network

The quality of the equipment is unsatisfactory and corresponds to the pre-production sample. Unfortunately, no operating instructions or drivers were found on the Russian website. The international site was more informative; it suggested downloading the driver under the loud name windows.rar and instructions with the no less intriguing name download.doc. It’s interesting that for UPS UP-D650VA and UP-D1200VA instructions from UPS-850GP are offered for download.

Warranty conditions for Krauler products are not publicly available.

The UPS case is made of metal and has a classic layout, a chassis closed with a U-shaped cover and a plastic front false panel. The quality of workmanship and painting is good. Nice KRAULER logo stamped on the side, ventilation holes, soft plastic legs.

The front panel of the device is beautiful. The UPS will look great next to the modding case. Alas, the quality of the LCD display is very low - it is readable with contrast at an angle of 10 degrees up vertically, but already at 5 degrees down, the image disappears completely.

The rear panel is typical for such devices. The USB interface is at the top, a block of four IEC320 sockets is in the center, one of the sockets is designed to connect a powerful load and is not provided with battery power. At the bottom there is an input block with a fuse and a pair of RJ-11 connectors to protect telephony. Internal structure

The internal design of the UPS is traditional. Top position printed circuit board, in the rear there is a transformer and an inverter. In the front there is a battery and control and charging circuits.

The UPS uses a battery from the company, the battery is made, like most similar products, in China.

It should be noted that the NP series battery is designed for a 20-hour discharge mode. With an hourly discharge mode, its capacity, according to the manufacturer, is only 4.2 Ah. Typical battery discharge time when operating in a UPS is 10-30 minutes. In this mode, the capacity will be less than 4 Ah.

Replacing the battery requires complete disassembly of the UPS and is performed at a service center.

All main electronics are located on one two-layer printed circuit board. The quality of the printed circuit board is very good, the soldering is neat, the elements are installed evenly, the correspondence of the elements to the circuit diagram is signed. Installation of elements is one-sided.

The noise filter on the board is wired but not installed. Overvoltage protection in the network is implemented using a varistor.

Switching is carried out by a relay, the maximum switching current is 7 A, at a voltage of 240 V, which in this case allows you to connect a load with a maximum peak power of up to 1680 VA.

An inverter with four transistors, produced by , generates an approximate sinusoid. The inverter is made according to a conventional, low-frequency circuit, with a transformer. The power consumption of the UPS when operating on batteries without load was 11 W. The transistors are located in pairs on two small radiators with an area of ​​80 sq. cm. every. The type and quality of the generated signal at different loads are clearly visible on the oscillogram.

Testing

The UPS under test is equipped with an AVR system - automatic regulator voltage, sometimes called a stabilizer, which allows you to adjust (increase or decrease) input voltage, obtained from the mains without switching to battery power. The implementation of this module differs depending on the model and manufacturer, in this case the AVR has one step-down stage (to normalize the increased voltage) and one step-up stage (to normalize undervoltage mains). AVR hysteresis 6-9V. The graph below illustrates the operation of the AVR.

Based on the test results, the AVR's performance can be considered unsatisfactory. The UPS provides stabilization within the range of -14% +9%, this greatly exceeds the limits established by GOST 13109-97. The effective operating range of the AVR is 170-255 V.

The response time of the AVR system was determined from the oscillogram at a load of 100 W. Switching the transformer windings took less than 1 ms. This is a very good result.

When the mains voltage goes beyond the set range, the UPS switches to battery power, notifying the user about this by means of an audible signal every three seconds. The operation of a UPS with a battery discharged to a critical level is accompanied by a signal with a frequency of one second.

The transition time to the battery was determined from the oscillogram at a load of 100 W. The transition time to battery power was less than 5 ms. Not a bad result, but upon closer examination, an “artifact” of the inverter’s operation was discovered. During the first periods, the inverter does not produce the rated voltage. In the oscillogram below you can observe the process of switching to batteries at 100% load.

The UPS has been tested for battery life at various load levels. Synthetic tests were carried out on a load of resistors of 40%, 50%, 60%, 80% and 100% of the UPS rating. Output voltage measured with a digital multimeter. During operation without load it was 231 V.

Interest

The UPS does not operate at rated power; during testing at 100% load, the voltage dropped to 175 V. The temperature of the inverter and transformer transistors reached 84°C. The UPS load power recommended based on test results is no more than 200 W.

For testing under real load, a test computer with the following configuration was used:

A total of four test computer configuration options were assembled:

1. Integrated SiS Mirage, 400 W PSU with passive PFC: DIVX-SiS
2. ATI X700, 400 W PSU with passive PFC: DIVX-ATI
3. ATI X700, 400 W PSU with passive PFC: 3DM5-ATI
4. ATI X700, 550 W PSU with active PFC and autovoltage: 3DM5-ATI-PFC

In the diagram from left to right:

DIVX-SiS- Configuration with built-in motherboard video adapter. Play from hard drive HD movie Shrek (1280? 720? 24? 1700 kbps video bitrate, AC3 track 384 kbps). CPU load 17-25%.

DIVX-ATI- Playback of the HD movie Shrek from a hard drive (1280? 720? 24? 1700 kbps video bitrate, AC3 track 384 kbps). CPU load 17-25%.

3DM5-ATI- The test package 3Dmark05 v1.1.0 was run, 1024×768 in GT1 mode, which should imitate the operation of a modern toy.

3DM5-ATI-PFC- Configuration with a 550 W power supply, active PFC, auto-voltage 127-230 V. The 3Dmark05 v1.1.0 test package was run, 1024×768 in GT1 mode, which should simulate the operation of a modern toy.

Battery charging parameters are one of the most important factors affecting the service life of the battery, and, consequently, the UPS itself. For the battery used, the manufacturer has set a maximum charging current of 2.1 A. Given the importance of the battery charging mode, two tests were done. In the first (yellow line) the UPS was discharged to a load of 100% (400 W) before auto-shutdown, in the second (red line) after being discharged to a load of 50% (200 W), the UPS was successively discharged to a smaller load until the battery was completely discharged.

Restoring the charge after a deep discharge took 20 hours. Fully charging the battery required 35 hours, the charging current at the beginning was 750 mA. During the first 20 hours, the charging current averaged 250 mA. It took another 15 hours to achieve a charging current of 50 mA and a voltage of 13.4 V. Restoring 90% of the battery capacity after an intense discharge took six hours. Based on the measurement results, the operation of the charging circuit was found to be unsatisfactory. The disadvantages include a very low final charge voltage, which leads to a decrease in battery capacity. On the plus side, we have an increase in battery life. When the mains voltage deviated from the nominal value, the charging current varied ±25%.

To test the cold start system, the UPS was connected to the load without being connected to the network. The UPS turned on at full rated load, but for the first 0.7 seconds a voltage of 170 V was output. The tested UPS does not support operation with power supplies equipped with APFC with an autovoltage of 90-240 V.

For communication with a computer, the UPS has a USB2 interface. To check the communication interface with the PC, the UPS was connected to USB port supplied cable. The UPS does not support the Smart Battery standard; it is automatically detected in Windows system XP, and the following devices appeared in the device manager:

In our kit software did not have. On the English version of the site you can download not the most latest version UPSilon 2000. This software is discussed in a separate article. Conclusion

The device under test is a budget UPS with an unobvious scope of application. We cannot recommend such a device for use due to its shortcomings.

Advantages

• Metal body
• Large and bright LCD display

Flaws

• Shortage of half of the rated power
• Inefficient charging circuit
• LCD display has small viewing angles
• Replacing the battery requires disassembling the UPS
• No Smart Battery support

It’s always unpleasant when the power goes out unexpectedly, but if the equipment is connected through an uninterruptible power supply, then it can maintain its operation for some time, which is enough to close all applications and turn off the computer in normal mode. And if turning off a computer or other equipment is unacceptable, then you need to use a more powerful UPS, or connect more capacious batteries to the existing one.

All UPS are designed to maintain the operation of equipment of a certain power, for example, for office or home use 500-1000VA, or for more professional use, with a power above 1000VA - these models already have a fan, so they are designed for long-term operation. However, the price of such models is quite high, and the high power to power one server or several routers and radio equipment is excessive. They have more capacious batteries, which allows you to supply power for a long time. However, nothing prevents you from installing similar batteries to budget models.

Questions often arise on the Internet - is it possible to install more capacious batteries in the UPS, instead of the standard ones? There is a heated discussion describing horror stories about how their device failed, etc. The most courageous even connect car batteries of 60 ampere-hours or more, but they have high internal resistance and the UPS does not correctly determine the remaining battery charge, often turning off the load ahead of time. Therefore, we will immediately answer the questions that arise:

1. Is it possible to connect batteries with a larger capacity than the standard ones - yes, it is possible.

2. Will more capacious batteries be charged? They will, but the charging time will be several times longer.

3. Can the UPS fail if more capacious batteries are connected to it - maybe, especially if it does not have forced cooling. However, you can always install an additional fan for ventilation.

As an example, let’s take an old, worn-out uninterruptible power supply and, using its example, we will describe the installation of batteries step by step.

UPS PowerMANRealSmart 2000 refers to the average level. Its power is 2000VA, produces a pure sine wave and has the ability to cold start. There are 2 12 volt batteries with a capacity of 14 amps installed inside. Connected in series, so the operating voltage is 24 volts. All powerful UPSs have a battery voltage of more than 12 volts, usually from 24 to 96, in the latter case 8 batteries are installed inside.

On the front panel there is a charge indicator scale and a load scale, indicators of operating modes, overload and the need to replace batteries. There is a single power button in the center.

There are 2 blocks at the back for connecting equipment. The left one is only protection against distortion, the central one is used to supply power in the absence of mains voltage. On the right is the connector for connecting the power cable, above is the thermal fuse button. There is built-in telephone line protection or network cable and a COM port for connecting to a computer.

Opening the UPS case PowerMAN. There are no standard batteries in it anymore; there are only 2 cables left to connect them.

As a replacement, we will install the most capacious batteries that can be bought in computer stores - SVENSV12170. Voltage 12 volts, capacity 17 ampere hours. Bolt terminals. Batteries of smaller capacity usually use regular connectors for connection, like car speakers.

The cost of such a battery SV12170 only 1300 rubles. For our event we need 2 batteries because we need to assemble a 24 volt battery.

On one side the UPS PowerMAN there is a large transformer that weighs 10 kilograms, and the battery compartment is closed with a metal strip, so you need to disassemble the other side.

On the other hand, in order to unscrew the protective strip, the fan had to be removed, because Otherwise you won't be able to get to the bolts. Batteries SVEN 17V 17A.H. fit right next to each other. The gap between them and the board is about 2cm.

The cables from the front panel must be carefully lifted up. In the future, they will need to be carefully laid without strong bends. White marks on the board are due to poor quality flux removal during production.

Speaking of cooling. 4 aluminum plates are radiators for transistors, which supply a sinusoid to the load through a transformer, so they become very hot during operation. On RealSmart 2000 the fan is installed standard, for others it must be installed independently.

Next we move on to the most interesting part. Standard wires are no longer suitable for connecting these batteries. And the standard wiring for connecting 2 batteries too. Therefore, you will need bolt terminals, a piece of 10 sq. mm copper stranded cable, bolts, nuts and washers to connect the terminals to the batteries.

For carrying out the work, an ordinary soldering iron, even one with 100 watts, will not be suitable - it cannot heat the terminal, so we will use a 2000-watt construction hair dryer, to match our uninterruptible power supply. You will also need pliers to hold the terminal in the air flow. The heat gun should be placed on its side while working.

We expose the end of the cable and solder it to the terminal. The soldering process occurs in the following way: the terminal is heated, then a wire with flux and tin is inserted into it and filled to 2/3. Next, you need to wait until it warms up evenly and lower the cable into the molten solder. For a reliable connection, you need to remove and immerse the cable in the terminal several times. Naturally, it is necessary to achieve the necessary heating of the copper core of the cable, otherwise there will be no reliable contact. Then carefully move the terminal with the cable to the side and let it cool.

You can insulate the terminal with electrical tape or heat shrink.

We measure the length of the cable to connect the 2 terminals and repeat the operation. Due to the fact that the batteries are located almost flush to the board, the terminals need to be bent with pliers.

We perform a similar operation with standard UPS cables. They are somewhat thinner. Carefully cut off the terminal and expose the cable; it is important not to reduce the length of the wire, otherwise it will not be enough to connect to the distant terminals of the batteries.

As a result, we get 2 neat and reliable connectors. They also need to be protected with electrical tape.

Next, carefully connect the positive terminal of one battery to the terminal of the blue cable. Using a key can damage components on the board - be careful. Standard batteries PowerMANRealSmart 2000 were 7 centimeters lower.

And on the other hand, to the negative terminal of the battery - there is already more space.

We connect the negative terminal of the UPS to the negative terminal of the battery. You need to make sure that the bolt does not touch the metal frame.

And finally, carefully, so as not to short the key to the case, we connect the positive terminal of the battery. You also need to make sure that the bolt does not protrude beyond the dimensions of the battery. SVENSV12170.

We wrap the intermediate support-amplifier of the case with electrical tape and place strips of plastic under it to protect against accidental contact of the terminals with the case RealSmart 2000.

Ready! Turn on the uninterruptible power supply PowerMAN and it immediately shows 50 percent battery charge. To fill the full capacity, leave it on for 12 hours.

To further increase operating time, you can connect additional batteries, installed outside the case, for which you need to bring out the terminals for connecting external batteries from the back. Naturally, you should use the thickest wires to reduce resistance. After all, the higher the resistance, the sooner the equipment will turn off when the batteries are discharged.

UPS battery charger

I am publishing my article reader Alexander, who lives in Alexburg, or more precisely in Riga.

The article discusses in detail the principles of operation of batteries, the processes of charging and discharging, and provides ways to maximize the use of battery life.

There are very few such major works on the Internet now. Having seen the article, I realized that if properly prepared, it would be at least equivalent to a master’s thesis! I myself learned a lot of useful things from it, and I recommend it to my readers!

A LITTLE HISTORY or how it all started

In the early 2000s, I came across an old uninterruptible power supply BACK-UPS 600I from the Basurman manufacturer APC. I got it for free because its batteries were dead. Of course, I immediately tested it, bought batteries recommended by the Basurman manufacturer and “it worked for me”!

I wrote about such a UPS in an article about use.

I couldn’t be happier with him then. Of course, there is no light, but the computer and monitor are working.

Subscribe! It will be interesting.

But in one unfortunate moment my joy was ruined.

And who do you, Reader, think?.. Fucking hucksters. The first time I replaced two 6V/7Ah batteries with one 12V/7Ah it turned out a little cheaper. But when the battery died again within a year, I started thinking! Firstly, the battery had to be changed once every year or two. Secondly, I wanted the devices connected to the UPS to work not for a few minutes to “properly turn off the power,” but at least until the end of the calculation on the Premier line from Adobe.

This is where naughty thoughts began to arise in my mind: should I connect a 100-amp car battery (to be reliable) to my UPS. Moreover, the traders argued that only gel batteries should be used in the UPS, frightening with Great Punishments those who try to use much cheaper batteries for cars.

But I am a fairly literate person and have learned that you need to know the materiel! Otherwise, something might go wrong with the big bodabum! But you can’t trust traders. Therefore, I took up the study of materiel! As a result of my research, something that I am happy with to this day was born. Namely, I made it so that you can now connect a car battery to a UPS. That is, the UPS and the battery became friends.

INSTEAD OF A FOREWORD. Types of batteries

Uninterruptible power supplies (UPS) use gel rechargeable batteries(battery). And there are good reasons for this. I will not list them all, but I will explain the main ones. Imagine an office secretary with a twenty-kilogram battery in her hands. It's a funny sight, isn't it?..

Technically competent specialists who thoroughly know what it is electricity not so much. And specialists who know how a switching power supply works, how an inverter converts direct voltage into alternating voltage and even less. The average computer user is not interested in this. That's why gel batteries were created. Inside such a battery, of course, there is no hair gel or helium, as an inexperienced secretary might think from the name. Inside there is the same sulfuric acid and the same lead, as in a regular car battery that has been familiar to us for more than a century. Only there is still a fine mesh with very, very small cells made of non-conductive material, which holds the acid like a sponge in its pores. Also, such a battery does not require maintenance.

Imagine the same secretary with a hydrometer in her hands, with a jar of electrolyte and a bottle of distilled water on the table. UPS manufacturers strive to protect themselves from lawsuits and claims. Therefore, they use the safest batteries in their devices from the point of view of use by an inexperienced consumer. But we know the materiel :)).

I will not go into the weeds and touch in great detail on existing types of batteries, the issue of battery operation under different conditions (huge starting current, long-term load, constant undercharging, overcharging, electrolyte boiling off, deep discharge, operating temperature, etc.), although some -which of these concepts will be discussed in more detail further in the text. I simply guarantee and responsibly declare, based on my practical experience, that under certain conditions it is possible to use cheap starter batteries in a UPS instead of expensive gel ones! So, let's begin!

Battery THEORY. Required for studying!

Here I will only touch on the theory of MAINTAINED lead-acid starter batteries used in cars and produced in compliance with all technological production standards (in other words, not produced in the Chinese basement of Uncle Liao or in the janitor's room of the former house of Ippolit Matveevich in Stargorod). They are the cheapest but at the same time the most “knowledge-intensive” to operate.

If they are used and maintained correctly, but most importantly, charged correctly, they can last more than 15 years, or withstand more than FOUR HUNDRED 100% discharge-charge cycles or more than a THOUSAND 30-40% discharge-charge cycles! It's been tested, I guarantee!

The principle of operation of the battery

The battery has two extreme operating states - completely discharged and fully charged. Let me touch on these two states in more detail. Any car battery consists of 6 “cans”. This is slang for a vessel that contains plates and acid. The plates in these vessels are connected in series. Here is the first fundamentally important point. One “can” also has two extreme operating states - completely discharged with a voltage of 2.00 volts and fully charged with a voltage of 2.40 volts.

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• The voltage of a completely discharged battery is 12.00 volts (6 x 2)
• The voltage of a fully charged battery is 14.40 volts (6 x 2.4)

How can this be, you ask? After all, the voltage on the battery is never more than 13 volts. And you'll be right. The voltage on a fully charged battery will be in the range of 12.75 - 12.80 volts with an electrolyte density of 1.26 g/cc and at a temperature of 25 degrees Celsius. But where does 14.4 volts come from?.. During charging and discharging, complex chemical processes occur in the battery, which last for some time after the charger or load is disconnected. This can be called chemical inertia. The density of the electrolyte changes accordingly.

The temperature in the battery can also be different (from -40 to +50). When some processes occur in the battery, all its indicators change. And they are interconnected. A voltage of 12.75 - 12.80 volts is the “rest voltage” of a fully charged battery. For a fully charged battery, the voltage will drop when a load is connected. When the load is turned off, the voltage will again tend to the same 12.75 - 12.80 volts. But since a certain amount of energy was given, the voltage (depending on this amount) will not rise to 12.75 - 12.80 volts.

The battery is considered discharged by a certain percentage. Accordingly, when charging, the voltage increases, and when charging stops (the processes inside the battery also stop), the voltage again tends to the resting voltage.

And here on the podium appears His Majesty Electric Current, measured in amperes. The greater the load current on the battery, the more energy the battery will release per unit time. And it will discharge accordingly. The battery's electrical capacity is usually written on it.

The electrical capacity of the battery is the product of the direct current of the battery discharge and the discharge time at the rated voltage (for a car battery this is 12 volts).

Accordingly, in an hour, a battery with an electrical capacity of 60 Ah can deliver 60 amperes with a voltage of 12 volts before it is completely discharged. In practice, it looks like this: if the battery is loaded with a current of 60 amperes for one hour, its voltage will drop from 12.75 - 12.80 volts to 12.00 volts. This is the fundamental basis of battery operation.

In practice, the battery has one very unpleasant feature. Self-discharge current. Moreover, this current increases if the battery is in the sun and the temperature of the electrolyte in it rises. But the battery capacity also increases accordingly. But in winter, the self-discharge current decreases. But the battery capacity decreases accordingly. Therefore, there are standards for the operation, storage, and preservation of batteries that take into account all these factors.

With a new battery electrical capacitance about 60 Ah, the self-discharge current at a temperature of 25 degrees Celsius usually does not exceed 20 milliamps. This means that at room temperature the battery can be discharged to half its electrical capacity in four to five months. As the battery ages and is used intensively, the self-discharge current increases with each discharge-charge cycle. When the battery is loaded, the self-discharge current and the load current are summed up. But what about 14.40 volts, YOU persistently ask again?... Here there is a second fundamentally important point.

Battery charging principle

There are two ways to charge the battery:

• Charger DC
• Charger constant voltage

It is impossible to say which one is better. It all depends on what you want to achieve. Fast charging or full charging. I prefer to charge the battery using the second method. And then I will justify my position.

A DC charger is much simpler in design and cheaper to manufacture. A constant voltage charger is much more complex in design and more expensive to manufacture. Those who charged batteries with old Soviet chargers (by the way, very remarkable in their technical parameters and reliability of execution and operation) know the theory.

If the battery is completely discharged, unscrew the caps on the battery, connect the battery to the charger, draw a current of one tenth of the battery capacity and charge for 12 hours. After 12 hours, we reduce the current by half (to one twentieth of the capacity) and recharge for an hour or two, until the electrolyte begins to “boil”, turn off charging. Boiling of an electrolyte is the process of releasing hydrogen vapor from it. Ideally, the electrolyte should not boil. Because then you will have to take a hydrometer, measure its density and add distilled water. Therefore, you need to constantly reduce the current.

If the battery has lost its capacity due to harsh use, deep discharge or simply aging, it can be charged in a couple of hours. And the electrolyte will begin to boil an hour after connecting the charger.

Constant current charging means that the voltage increases while charging. And as soon as the voltage exceeds 14.40 volts, the electrolyte will boil anyway. What to do in this case?.. Option one is to monitor the charging process by constantly lowering the current, keeping the charging voltage at 14.40 volts. Option two is to use an automatic machine that monitors this itself. But it monitors the voltage, lowering the charge current as needed. This is charging in the second way - constant voltage.

The second fundamentally important point is the correct charging of the battery to ALL 100% of its electrical capacity:

YOU CAN FULLY CHARGE THE BATTERY (TO 100% OF ITS ELECTRICAL CAPACITY) WITHOUT BOILING OUT OF THE ELECTROLYTE ONLY WITH A VOLTAGE OF 14.40 VOLTAGES!

I prefer to charge the battery with a constant voltage of 14.40 volts. The reality is that charging a battery to 100% is quite difficult. When the battery has reached 95% of its capacity, its charging current is very small, and at 99% it is simply scanty and can be only 30 milliamps. I will note one detail - this is all on the verge of boiling the electrolyte. Theoretically, the electrolyte begins to boil at a charge voltage of 14.41 volts, provided that the battery is made perfectly, and does not boil at 14.40. In practice, it can be either 14.38 volts or 14.42. It all depends on the battery manufacturer and individually for each specific battery. But I hope you, dear reader, got the point.

The disadvantage of voltage charging is the charging time. Typically, the battery reaches its full charge capacity (100%) in more than a day. The charging current at the initial stage is very important here. You can charge at the initial stage with a current of one-fifth of the capacity. Then the charging time will be reduced. Same as battery life, but not significant. No one has canceled the charging theory. It is preferable not to exceed the charging current of more than one tenth of the battery capacity. The choice is yours, reader.

Can a car battery be used for a UPS?

And now we come to the crux of the matter. How to use a starter battery for a car in a UPS. My BACK-UPS 600I UPS fits this perfectly!

The very first UPSs from APC of the Back UPS series charged the battery exactly according to the principle of charging the battery with constant voltage. There is a microcontroller for controlling battery charging. The estimated battery capacity for my UPS is 7 Ah. The charge current is 350 milliamps at the initial stage. At the end, the current drops to 10 milliamps (in fact, to a current slightly higher than the self-discharge current). Newer UPSs charge differently. I tested more new model Back-UPS CS 650 (I even wanted to buy it), but this iron beast keeps the voltage at 13.7 volts. When the charge current exceeds a certain parameter, this muck displays the Replace Battery icon on the front panel.

Of course, it can also be used with a car battery, but with a battery large capacity There may be problems with undercharging. You will have to use it with external charging(I will discuss this issue below, in the Practice section). And the voltage of 13.7 volts is not enough to charge the battery 100%. Therefore, I don’t need such a UPS for nothing. But with my BACK-UPS 600I UPS you can use a battery of at least 150 Ah. Yes, if the battery is completely discharged, it will charge it with a current of 350 milliamps for several days. But it is guaranteed to charge 100%. But in order to save time, you can again get out of this situation using external charging.

PRACTICE charging the battery in a UPS. We study the materiel

So, Reader, we have come to the heart of the matter. I'm glad to present what my Back UPS 600I has become over 14 years of use. 9 of them I use it with lead-acid batteries for the car.

I hasten to immediately convince the skeptics with a fear of hydrogen. Both gas outlet holes on the sides of the battery were sealed with latex from a condom (if anything happens, it will simply inflate). The caps on the cans are also screwed tightly. But during 9 years of operation there were no incidents. Therefore, now they are filled with silicone glue. I use two batteries. The batteries are connected with a common minus and a switched plus. From the inside it looks like this:

On the front panel we see a digital voltmeter that shows a charge voltage of 14.44 volts and an ammeter that shows nothing. This is my standard operating mode. We'll find out why it doesn't show anything below.

Now again, just a little bit of history. What you, Reader, see in the photo below are my very first devices for monitoring UPS. This is a dial voltmeter with an extended scale (measures voltage from 10 volts to 15 volts) and an ammeter with a homemade shunt. I needed to see both the current when operating from the battery and the charging current. If you need to make the voltmeter show the voltage not from zero, but from the desired voltage, the scale can be stretched using voltage dividers; there are diagrams on the Internet.

They were made many years ago and served faithfully before Aliexpress became a symbol of the era. Then I got wonderful and, most importantly, very accurate instruments (an ammeter + a shunt for it and a voltmeter) at inexpensive prices. This is what the UPS looks like with the ammeter turned on:

It shows the charging current. As you can see, the current is not large - only 50 milliamps. This is the UPS battery charging controller. One detail is worth noting. Only after I installed a digital voltmeter of such accuracy did it become clear how the charge controller works. The dial voltmeter could not record this.

The charge voltage periodically varies from 14.37 volts to 14.47 volts and can be at the same level for half an hour or 30 seconds. The charging current depends on the connected battery. If a battery with a capacity of 17 Ah is connected, the charging current is within ten milliamps. But here it’s impossible to say for sure. This is on the verge of instrument error. Maybe 14 milliamps, maybe 6 milliamps. One thing I can say for sure is that it is different for batteries of different capacities.

But the ammeter is not as simple as it seems. The beauty of it is that it can show electrical current in two directions. It will show the charging current and discharge current but with a minus sign. Now I will connect a load of about 180 watts to take 20 amperes from the battery. You can immediately see how the voltage dropped and how the ammeter began to show battery discharge with a negative value:

I configured the UPS for myself based on the fact that I would draw no more than 20 amperes of current from the battery. A load of 90 watts from 220 volts loads the battery within 10-11 amperes. But in fact, I now have two servers on the UPS, a router and a switch. This whole facility consumes about 30 watts from 220 volts, and from the battery within 4-5 amperes. Battery 58 Ah.

It is guaranteed that all this can work without electricity for about 7-8 hours (depending on the load on the servers). As soon as the electricity goes out, I receive an SMS and I can turn off the servers remotely. But I don’t think this will be required. In seven hours I will appear and switch to the second battery :)), using a button manually. And while this is all working, I’ll remove the battery from the car and connect it instead of the first one. That's another 7-8 hours. Well, within a day the electricity supply will be restored for sure. So far there have been no such force majeure events. :)) Well, if they do, I’ll splurge on a 100 amp battery. True, you can’t put it in the car. By the way, this is one of the reasons why I don’t use a battery with a larger capacity than my car can “swallow.” Although, as you can see, Reader, the system allows you to use a battery with a capacity of at least 1000 Ah.

Well, the readings a couple of minutes after the UPS power switched back to 220 volts. As you can see, the voltage is 13.08 volts and the charging current is 140 milliamps:

Charge after a small discharge

The connection diagram allows you to INDEPENDENTLY charge one of the batteries while the other is in use. Once every six months I switch between batteries in order to somehow equalize the aging process of both batteries. Wires 6 sq. mm.

It is worth noting that when the length of the wires is more than a meter, you need to use a larger cross-section. For myself, I calculated that with an operating current from the battery of 12-15 amperes and a wire length of 40 centimeters, the voltage drops by 0.008-0.015 volts. This is about an extra 3-6 minutes of battery life. At 7 hours this is insignificant. Accordingly, the shorter and thicker the wires from the battery to the UPS, the better, especially at high load currents.

The wonderful battery selection switch button allows you to connect an external charger. Also, this key, with certain skill, allows you to switch batteries during UPS operation from the battery. This has also been verified. Modern impulse blocks power supplies for computers hold the load if the mains voltage goes out for 0.8 - 1.2 seconds. And this is just enough to quickly “switch” the key to another battery when the voltage on the battery drops to a critical level.

The ammeter and voltmeter draw very little current. If you turn off the display backlight LED, the devices consume about one milliampere (I even specifically measured how much the voltmeter consumes by calling up units on the display - this is a smaller number of LCD segments), the device consumed 900-odd microamperes at a supply voltage of 11.11 volts. With the LED on (when the display is lit) about 3 milliamps. And is it important. After all, it is connected to the battery directly. I generally made the ammeter switchable, because its power is connected to the 220 Volt output of the UPS. I want to clarify here. The ammeter's power supply must be galvanically isolated from the circuit in which it takes readings. Its supply voltage ranges from 6.5 volts to 15 volts. I haven't found a suitable power supply for it. As it turned out, a power supply with parameters of 6-12 volts, designed for a load of 10 milliamps, is not so easy to find. But I didn’t have the patience to do it myself. I really wanted to quickly connect it instead of the switch that was there before. So I took a 400 milliamp, 7.5 volt phone charger and connected it to the 220 volt UPS output and made it completely switchable. This is to reduce the load on the 220 Volt output of the UPS when it is running on battery power. The voltage and amperage control key turns off the ammeter completely, and the voltmeter turns off the backlight, minimizing battery energy consumption. Well, in general, that’s all the explanations for the UPS control keys.

CHARGING with an external charger

Now I want to separately touch correct charging my UPS battery. As I mentioned above, I will tell you why I prefer charging the battery with constant voltage. I’ll touch on this issue using my charging as an example. She looks like this:

Its diagram can be found in Radio magazine. Many thanks to my dad, who found it and then soldered it and the author of this development - M. Shumilov for a competent and very useful device made from computer unit nutrition. Charging is quite complicated to manufacture and configure. But after this process, it will delight you with its accuracy and ease of charging the battery at a guaranteed 100% capacity. The indicator shows, in addition to current, voltage and charging power, the watt-hours spent on charging. This is what it looks like from the inside:

Charge voltage 14.40 volts(adjusted during setup). Precisely so that it is not 14.39 and not 14.41! It is important. The charging current is limited to the range of the battery that you plan to charge. My current is limited to 6.5 amperes. For my needs this is the optimal current.

This type of charging can charge batteries with a capacity from 20 Ah to 80 Ah. Of course, you can also charge a 150 Ah battery. But charging time will be about two days. When the battery is connected, the voltage drops and the charging current is maximum. Here you should pay attention to the fact that if you do not limit the charging current, for the first few seconds it may be the same as the battery capacity. As the battery charges, the voltage tends to 14.40 volts and the charging current gradually drops. As soon as the voltage rises to 14.40 volts, we can see one of the main parameters of the battery, which is not so easy to find out - SELF-DISCHARGE CURRENT. Using it you can find out how much the battery is worn out and what to expect from it in winter.

Another advantage of this charging method is that you will never overcharge the battery. It can stand on charge for at least 3 months. The electrolyte will never boil and it will be charged 100%. Unfortunately, industrial chargers of this type are very expensive, and the built-in ammeter with a voltmeter is direct proof that the charging is really not hacky. Unlike the shitty Bosh and other Vart, where the control indication is carried out by LEDs that light up due to some case of flatulence from the manufacturer. Now I accurately and without any confusion explained the figure of 14.40 volts.

After the charging process, you need to wait about 2-6 hours (depending on the battery capacity) until the battery comes to a resting state. The voltage will be about 13 volts. And within a day or two (when all chemical processes inside stop completely), the battery voltage will drop to a voltage of 12.8 volts. The process of self-discharge will begin. Now, I hope, it has become clear why I plugged the holes in the battery and do not worry about harmful fumes during charging. Periodically, previously once every six months, now once every couple of years, I test and service the battery. I use a hydrometer to check the density of the electrolyte in the jars and its level. Well, accordingly, I recharge the backup battery with external charging.

ABOUT THE CHARGE TABLE and more

Now, perhaps, it is worth giving an explanation to the table, which characterizes the degree of charge and discharge of the battery. I explained everything about charging above. Now for an explanation of the discharge.

As you can see, I have noted that the battery is discharged to zero when the voltage on it drops to eight volts. This is a rather subtle and also important question. Let me immediately explain the term “deep discharge” that I use later in the text. The battery goes into a state of deep discharge when its resting voltage is below 11.35-11.40 volts. This is the upper limit of deep discharge. As I said above, after disconnecting the load, the voltage on the battery begins to increase. It is very important that after 2-6 hours, depending on the battery capacity, this voltage rises to 12.00 volts. This means the battery has not gone into a “deep discharge”. Although, in my experience, even if the battery is briefly discharged to 11.90 - 11.85 volts, nothing bad will happen if it is immediately put on charge. And manufacturers often write the short-term inrush current next to the capacitance. This current instantly sends the battery into a deep discharge, but, as you can see, the battery can withstand this and serves in the car for 5-6 years. When starting the starter in a car, the battery is loaded with currents of up to 200 amperes and the voltage drops to 9 volts. It is important how long the battery is under LOAD in a deep discharge.

The UPS manufacturer sets the lower shutdown threshold at full load on the battery. Therefore, in my case it is about 7.55 volts with a load of about 30-35 amps. I checked on a dead battery when I tested the entire system. At 7.55 volts, the UPS is completely disconnected from the battery and “goes out”. And 8 volts in my table is indicated for full load. This is a “memo to self.” I did not rely on 7.55 volts to leave some kind of safety buffer. In general, it is better not to let the battery discharge until the voltage drops to such a low level. The battery sags in voltage more under full load than under 50% or 30% load. As soon as the load disappears completely, the voltage on the battery rises abruptly and then continues to rise more and more slowly until the actual discharge voltage.

When I tested the UPS, with a 20-amp load on the battery, when the voltage dropped to 8 volts, I reduced the load to 9 amperes, the voltage instantly rose to 10.6 volts, while continuing to slowly decrease. This is calculated empirically. If you discharge the battery with a load of 10 amperes, then the lower value will not be 8 volts, like mine, but more (it can be 8.4 volts, for example, or 9.0 volts) - I repeat, this is calculated empirically. If the load on the battery from the UPS is 10-20% of the calculated value, accordingly the voltage “sags” less, but the load on the battery is longer lasting. And accordingly, the battery remains in a deep discharge under load longer. But this is already “killer” for the battery. Therefore, you need to try not to let the battery become deeply discharged and, if possible, if it comes to this, immediately charge it. And when, during a power outage, we try to disconnect some additional devices from the UPS, increasing the operating time of the UPS from the battery, thereby forcing the battery to work longer in a deep discharge. Therefore, this issue needs to be resolved more fundamentally, coming from the other side - connecting a 150-amp battery :)) and not letting it discharge below the voltage calculated for a certain amperage.

When I described the operating time of my consumers (router, servers and switch) as 7-8 hours, this is actually 2-3 hours the battery will work in a deep discharge. And accordingly, its life time will be reduced quite significantly, but not so much that it will no longer work. But buying a car battery with a capacity of 58 Ah (operating time 2-3 hours) for 32-34 euros is much more pleasant than a battery with a capacity of 7 Ah (operating time 5-10 minutes) for 18-20 euros. Feel and savor the difference;))… And the car battery is MUCH more durable, more serious and more reliable than the gel “battery” that comes “included” with the UPS. Direct proof is the service life of my battery :). Yes, and a gel “battery”, after working for 20-30 minutes in a deep discharge, actually dies immediately - the plates inside it begin to deteriorate and its electrical capacity drops significantly, unlike a car battery, where the loss of electrical capacity from working in a deep discharge for 2-3 hours is measured in percentages .

I would also like to draw the Reader’s attention to one point in the operation of this particular UPS. Comfortable work with BACK-UPS 600I will be with a load of up to 200 Watts from the network alternating current 220 volt. Accordingly, about 25 Amperes will be drawn from the battery. At higher currents, the ceramic resistor starts to get very hot. If you want to provide autonomous power to electrical appliances up to 500 watts, you need a UPS designed for more power. And I would also like to draw your attention to the fact that the UPS inverter over 800 volts operates from TWO batteries connected in series (12+12=24 volts) due to its design features. I have not seen a kilowatt UPS powered by a single 12 volt battery.

PERHAPS, SELLERS OF SEALED, MAINTENANCE-FREE BATTERIES FOR UPS, AFTER READING EVERYTHING WRITTEN ABOVE, WILL NOT BE SATISFIED. I HAVE JUST ONE ARGUMENT, BUT REINFORCED CONCRETE – IT’S ALL BEEN WORKING STABLE FOR MANY YEARS. THE LAST TIME I BUYED A BATTERY FOR A UPS SEVEN YEARS AGO (TWO PIECES), ONE IS STILL WORKING, THE SECOND IS NOW WORKING IN A CAR AFTER SERVING IN A UPS FOR FIVE YEARS.

From the blog administrator SamElectric.ru

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An example of converting a UPS to a car battery

Reader BoB4uk I used the tips outlined in the article and assembled a similar device. More details in the comments around March 17, 2019.

UPS panel in different modes

There have long been debates online about whether it is possible to use car batteries in uninterruptible power supplies, and these discussions are not accidental - the cost of specialized batteries and car batteries, with equal capacity, differs by an order of magnitude. Meanwhile, there are a number technical problems, partly real, partly fictitious, which complicate the use of such batteries instead of standard ones in a UPS. However, faced with the need to quickly and cheaply obtain a powerful source of autonomous power, I successfully implemented such an integration scheme, and, moreover, I used not a new, but an already used car battery, i.e. reduced material costs to a minimum. So if anyone is interested in how to make a UPS work in offline mode for several hours with minimal investment, I recommend reading this post:

It so happened that the life situation forced me to think about what to replace the dead UPS battery lying in the attic with an old car battery. Actually, I live in a country house, and in Lately There were power outages. At the same time, I have three aquariums and a terrarium there, and all this requires that interruptions in the power supply do not exceed 15 minutes. And I work in Moscow, so I leave my home for a long time. To top it all off, the battery of my old UPS was completely dead and attempts to restore it were unsuccessful, and at that moment I did not have the money to buy a new battery. But, as I often like to say, progress has two main engines: laziness and lack of money.
And so, I took an old battery from the attic, which even in winter frosts refused to start the engine, brought the electrolyte level in it to normal (added distilled water) and fully charged it with a charger.

Then I connected contacts to it on fairly thick copper wires. Just in case, the fireman installed a power interruption button (set it to 30A so that it wouldn’t burn out), but this is not a prerequisite. The button is needed mainly for transportation, so as not to accidentally close the contacts (I immediately made my device with the ability to transport it anywhere so that I could get electricity anywhere, if necessary).

I unscrewed the lids of the “cans”, but covered them on top with a board and fixed it so that it protected from splashes, but did not interfere with gas exchange. It is STRICTLY PROHIBITED to seal jars! This will cause the battery to explode!

Next, I packed the entire battery into a bag, glued the bag on top with tape, but at the same time deliberately made it not airtight to allow gas to escape. Well, for greater convenience, I placed a piece of plywood on top of the bag, on which I placed the button, and attached a transfer handle. It turned out very convenient:

type of battery

And so, the preparation of the battery is completed - we begin to remodel the UPS itself.

First, we disassemble it and take out the old battery. In principle, as a rule, it can still be restored and used for other purposes where less power is required, so do not rush to throw it away, despite the fact that we no longer need it in the UPS.

The first real technical difficulty that you may encounter when using a car battery in conjunction with a UPS is overheating. During active operation of the transformer (i.e., when charging or discharging the battery), strong heating occurs. If a standard low-power battery is used, then heating occurs quite briefly and does not pose a threat. But if we plan to use a battery at 100 a/ch, then the heating will be significant and, with a high degree of probability, can lead to failure of the UPS.

I solved this problem by installing forced cooling. In the place where the battery was installed, I installed a cooling fan from the old processor. This is an almost ideal option, since such a fan is powered by 12V (i.e., you can use battery voltage), withstands voltage surges (you can simply power it from the wires to the battery) and is designed for long-term continuous operation (and, by the way, it is not particularly noisy) . You can attach the fan to the case in any way you like (I used a self-tapping screw for this, but glue can also be used). The main thing is that the airflow is directed towards the transformer.

The space in the case seemed to be specially designed for a fan

In order to ensure air flow, holes need to be drilled in the front and end parts of the UPS case

On the picture front side- on the back it’s the same

We connect the fan power to the wires coming from the battery. It is best to equip the wires themselves with connectors to be able to disconnect the battery from the UPS for transportation. The connector can be anything, the main thing is that the cross-section of the metal in it is not smaller than the cross-section of the wire. Personally, I used male-female terminals, for which I drilled a hole in the UPS case and brought the wires out. An important condition is that the wires do not have the physical ability to touch. It is better to take them out at such a distance that this would be completely excluded, because short circuit battery failure can lead not only to damage to the UPS, but also to a fire.

This is how it was all located under my table

The main advantage of this scheme is the minimum price. Considering that they are using a battery that has already served its purpose, which can simply be thrown in the trash or, at worst, sold for 100 rubles for scrap or melted down into sinkers for a donkey. Of course, its capacity will be lower than that of a new one, but it will still be many times greater than that of a standard UPS battery. In my case, during a power outage, the battery worked without strain for 30 minutes and only dropped by 3% during this time. I think this is more than enough, given the actual absence of price.

This is what my workplace looks like

However, given the many skeptical opinions and outright myths about the impossibility UPS usage with a car battery, I will dwell in more detail on the arguments that skeptics make and refute each of them, so if you are in doubt, read on:

Short service life of a car battery in a UPS. Yes, compared to a special battery, a car battery will last less, and this is really due to the structural features of the plates. But skeptics are clearly wrong about the numbers - they claim that a car battery will last 3 years, and a special one - 10 years. I will say this, my original battery in the UPS died completely and irrevocably after 5 years of operation. I can’t say how long a car will last, but even if we take the figure of 3 years as true, the difference between three and five years is not that big, especially considering the difference in price.

A car battery will die after 10-15 charge-discharge cycles. Yes and no. Car batteries really don’t like to be completely discharged, and in a car this situation almost never arises. An uninterruptible power supply is capable of drawing out the charge almost completely, and if systematically brought to this state, i.e. completely discharge the battery, it will indeed fail quite quickly. Not after 10-15 times, of course, but it may not last 30 cycles.

However, this problem is very easy to treat - any UPS can be programmed so that it does not wait until the battery is completely discharged, but turns off when the charge drops to a certain percentage of the full capacity. So you can set it to turn off at 20% charge, and the longevity of the battery is ensured. You can also set the operating time - say, three hours. But it seems to me that it’s better to set a limit on the percentage of charge (however, I didn’t limit anything myself - fish are more expensive to me than a battery, it’s better if it breaks). Well, for residents of city apartments this question is not relevant at all - it is very unlikely that the electricity will be regularly turned off for a long period, so even without additional settings A complete discharge of the battery in a city apartment is unlikely.

And if you do not allow the battery to completely discharge, then it will last a long time, because a car battery is designed for constant charging and discharging, provided that at least part of the charge will always remain. Visual proof is the operation of the car. The driver starts the engine every day, i.e. very seriously discharges the battery (especially in winter and on a carburetor car), then the battery is charged while driving. The next day the cycle repeats. How many days a year is the car used? How many years has the battery not been changed? According to my conservative estimates, this is about 1000 charging cycles, which is absolutely enough for a UPS.

The car battery will not be charged from the UPS. This is complete nonsense and banal calculations from a school physics course will confirm this. The UPS charging current is really about 14V (13.8, as a rule). In this case, the nominal voltage of the battery is 12V (in practice, without load, it can be up to 13V). But where do skeptics get the idea that there is 15V in a car and that 14V in a UPS will not be enough, I don’t understand. Let's look at it in detail:

In a car, the voltage is not constant - it varies from 11V to 15V and on average is about 14V (measure the voltage at the car battery terminals with a tester in different operating modes and see for yourself). No, I do not rule out that modern foreign cars may have a more or less stable voltage, and that it may be somewhere around 14.5V, but carburetor cars that were driven on the roads with exactly the same batteries as today for more than one decade, they clearly do not have such a stable and high voltage. For example, on my old machines 15V was very rare; on the contrary, more often the voltage dropped closer to 13V under full load or was at 14V under moderate load. And my batteries, like those of all other car owners, worked absolutely fine there. So 14V in the UPS to charge the battery is not a hindrance.

Another thing is that charging depends not so much on voltage as on current strength - in simple terms, voltage is responsible for the very possibility of charging the battery, and current strength is responsible for the time of this charging. With a battery rating of 12V and a UPS voltage of 14V, a difference of 2V is more than enough for the actual charging process. But the current strength in most UPSs is significantly less than that of car generator. However, this does not affect the ability to charge, but the longer duration of this process. It is possible that a large-capacity battery will take several days to charge, but it will be fully charged, 100%, that’s a fact.

For example, my battery charged from 97% to 100% in about 12 hours, but the charging process was completed and at 100% the UPS turned off further charging

Thus, the inability to fully charge the battery and the fact that the UPS will constantly operate in charging mode is a myth that we have successfully dispelled. Another thing is that the duration of the battery charge will lead to overheating of the UPS, but we have already solved this problem by installing forced cooling. Of course, to speed up charging you can use a car Charger, but this seems inconvenient to me - I deliberately wanted to make a system based on the “turn it on and forget it” principle, so I consider forced cooling to be a more reasonable option.

During the charging process, explosive hydrogen and acid vapors will be released from the car battery, while the special battery for the UPS is sealed. There is a greatly exaggerated truth and pure fiction here - let's find out.

First of all, about the fiction - the batteries used in the UPS are not sealed! They have a valve that prevents leakage of electrolyte, but at the same time allows gas to pass through completely calmly. In fact, the battery cover for the UPS has a couple of barely noticeable holes, which are not made so that this very cover can be pryed off with a screwdriver. These are the exits of the gas outlet channels. Under the lid there are the same cans, each of which is equipped with a rubber cap that fits tightly to the neck of the can and is supported on top by the battery cap. When the gas pressure increases, it exits into a special channel, and all these channels are reduced to those two holes that are on the surface of the battery. Moreover, on batteries from UPSs or from powerful flashlights they even write that they cannot be charged in a sealed place, and they write this precisely to prevent an explosion.

So those batteries that are used in UPSs are far from sealed and are also capable of releasing hydrogen. And they do this very actively - it is no coincidence that the main cause of death of such batteries is the evaporation of water from the electrolyte. If they were sealed, there would be no place for water to evaporate.

So we realized for ourselves that the battery installed in the UPS from the factory evaporates hydrogen in the same way as a car battery.

Now let's talk about exaggerated facts. First of all, we are talking about acid vapors. Yes, such vapors can be harmful to humans, but the question is how many there are. To answer this question, remember how we deal with batteries in cases low level electrolyte in jars. We add distilled water and not an acid solution - why? Yes, because first of all, water evaporates (more precisely, it hydrolyzes, decomposing into oxygen and hydrogen), and the acid itself remains in the battery almost completely. Accordingly, over time, the acid concentration rises, and by adding water we dilute it to its original value. From all this it follows that the acid practically does not evaporate from the battery, or rather, it evaporates in negligible quantities, which, as mathematicians say, can be neglected.

Another point is that when the electrolyte boils, splashes of acid can hit the outer surface and then, over a long period of time, evaporate completely. But, firstly, evaporation of the electrolyte occurs only with a high charge current (let me remind you that this indicator is low in our country), and secondly, it was not by chance that we covered the surface of the cans with a board (even if splashes fly, they will not fly outside contour of the can).

Thus, acid evaporation can be considered insignificant and does not pose a danger.

Now about hydrogen. Yes, it evaporates and, most likely, in slightly larger quantities than when charging the original UPS battery. But, I dare say, in much smaller quantities than when charging a car battery with a charger.

I think that all those who have a car have definitely encountered charging the battery at home. And in winter, many motorists generally use two batteries - one in the car, the other charged at home. Accordingly, all sold chargers have a large amperage, which reduces charging time, but almost always leads to boiling of the electrolyte. It is because of this that we unscrew the caps of the battery cans. Naturally, during the charging process with high current, and even with open cans, a lot of hydrogen is released. But no consequences were recorded. Moreover, they did not exist in Soviet times, when in almost every car owner’s apartment in the winter there was a battery charged, connected to the network through a light bulb.

And here it should be noted that the hydrogen released when charging a battery is completely harmless to human health. It is dangerous only because when mixed with air in a 2:1 ratio it forms an explosive mixture. But let’s remember the rule about what occupies the entire volume provided to it, and let’s see how much hydrogen is released during charging, and how much oxygen is contained in a standard apartment, not to mention your own home. Conclusion - the ratio of “explosive gas” in this situation is unattainable, because hydrogen will be much less than necessary.

This is confirmed by the experience of our fathers charging batteries at home. And recent history, as far as I know, does not have widespread examples of the danger of hydrogen released from a car battery when charging it at home. Even on the sites of skeptics who consider it impossible to use a car battery in a UPS, there is not a single reliable evidence of the dangers of such an action. So all the talk about an “explosive mixture,” although it has a physical basis, has no practical confirmation in relation to charging batteries at home (including from a UPS). Of course, I would not recommend placing the battery near sources of open fire or using it as a stand for an ashtray, but under the table near the computer, hydrogen in such quantities will definitely not pose a danger.

The software on the computer and the indicator on the UPS will incorrectly display the remaining operating time. Yes, if you do not reflash the UPS, then there is some problem here. The remaining battery life is calculated based on the battery capacity, remaining charge and current load. Accordingly, the capacity is built into the UPS firmware, and it is it that is used when calculating time, which leads to incorrect information. But this can be fixed by changing the UPS firmware. However, this is not easy to do for all devices, and in addition to the skills of a mechanic, you will also need the skills of a programmer.

On the other hand, this is not critical, since the battery charge will be determined accurately. The charge is calculated by comparing the rated current with the current in the battery circuit. Accordingly, this value will be calculated absolutely correctly. As a result, we will have an adequate display of the remaining charge as a percentage, which, it seems to me, is quite enough. For example, on cell phone we see only a schematic level of battery charge, well, sometimes percentages, but not the remaining operating time. And yet this information is enough for us. It’s the same with a UPS - the percentage of remaining charge is quite comprehensive information.

Thus, one can conclude that using a car battery in conjunction with a UPS is quite possible. Economic questions still remain open, because if you specifically buy a new battery for these purposes, then you really need to look at the survivability of the battery under such operating conditions, and time will tell. But if you use a battery that has already been used in the car, as I did, then the conclusion is obvious - it is not only possible, it is very profitable and convenient!