Do-it-yourself li-ion battery charge balancer. Battery equalization ensures long runtime and extends battery life. Making a balancing charger

Of course, a separate charge. But that's just for my particular case.

Often you have to work in the field without a network, a screwdriver is always at hand. Batteries are already old, an improvement was suggested. I shook out the dead NiCd from the screwdriver cartridges and stuffed it into both LiPo cases, each for 5 cans. A blunder, but you need to charge it in the same way in the field or in the car and it is desirable to charge it with balancing, because all 5 cans in each acc behave in their own way, ketai affects. Balancing when charging can be done in different ways, the ways are dark. The simplest is the braking of recharged cans by a load, transfer to heat. This is what the desktop IMAX B6 does, but I don’t like that it charges the entire battery for a long time when balancing is on.

I figured it out and thought that the easiest way would be to charge each bank in the battery separately. Somehow googling ways of balancing came across a similar thought:

"Bloody cheaters... When I was thinking about this, I was going to build a bunch of DCDC"s where voltage of each contact is individually controlled => each cell might be charged with individual charge plan. Apparently, this is just too complex. "

And it seemed to me less complicated: we sculpt a DC-DC with 5 outputs and hook a charger chip on each, of which there are a legion for Li-Ion! And, I thought, it should be less warm: you don’t need to slow down the banks! (Yeah, right now, charging mikruhi are heated like bastards!)

Here's the diagram that came up:

The circuit is simple, there was a problem only with the choice of the transistor. I first stuck the IRLS3034 with a wide gesture, in which the shutter capacity turned out to be too tough for the LM3478 driver, I had to put something less showy. For each channel - according to STC4054G, the option is cheap and satisfies the task. Here is the assembled board, divorced in one layer:

The manufacturer of the STC4054G charging chip recommends making the tracks on the board as thick as possible and, if possible, using polygons on both sides of the board for heat dissipation. I didn’t listen to the gouging, but in vain: the mikruhi are heated as they should, even with a charge current of 400 mA per jar.
And from another angle:

Charges and heats up, infection:

Well, if it's hot, it needs to be cooled down. I picked up a convenient aluminum case, drilled a cover for connectors, fasteners and LEDs. Round holes - round cutter, rectangular - rectangular)

Assembled and ready to sail:

There was an idea to paint it black, but too lazy. Yes, and this is pampering - this hedgehog is written to live in a car under your feet closer to the cigarette lighter.

I'll think about balance next time. I really like the idea of ​​​​a Robin Hood transformer, which it takes from rich cans and gives to poor banks in the battery. It seems like the efficiency is higher and the heat is less. But then again, rich batteries are milked back and forth until the poor ones are flooded; this isn't very good, is it?

UPD: According to the parameters of the transformer and ratings. The transformer was wound on a not very good core, what was at hand, 2 x MP140-1, KP19x11x4.8. Primary 21 turns 0.35 wire, secondary simultaneously 11 turns wire 0.51. Frequency setting R1C1 - at ~ 100 kHz, 4.7 kOhm / 0.1 uF. Feedback divider R2R3 - 21 kOhm / 8.2 kOhm. R4 - 75 kOhm, shunt R5R6 - 0.1 Ohm each (total 0.05 Ohm). VD1 - SMBJ15, VD2 - SM4005. VD4 of some Schottky from 1 A, C5 - 330 uF x 25V, VD8 - zener diode 5V1, C10 - 0.1 uF. R7 - 470 ohms, R12 - 2 kOhm, which gives approximately 400 mA.

Why do we need balancers for 12-volt batteries? When you have a 12 volt system, then all the batteries, no matter how many of them are in parallel, and they always have the same voltage. But when we switch to 24 or 48 volts, then there is a problem with different voltages on series-connected batteries. Because of this, when charging, some batteries go into overcharging and begin to "boil", while others are undercharged, and as a result, the entire battery chain quickly loses capacity and generally becomes unusable.

And even completely identical batteries eventually scatter in voltage anyway, so even purchased batteries from the same batch will not save you from the problem. To solve this problem, various balancing devices have long been used, these are either separate balancers for each battery, or blocks of 24 and 48 volts. Balancers can significantly extend the life of the battery.

I myself will switch to 24 volts in the near future, since the currents in the system have already become large and I will also need balancers. In search, I found several options that are different in terms of capabilities, price and principle of operation, and below I will review these balancing devices.

VICTRON BATTERY BALANCER

First I came across these balancers (photo below). This, judging by the description, is active balancers with a balancing current of 0.7A. Active, this means that the energy from a more charged battery is poured into a less charged one, and not just burned on the resistance. But I'm not completely sure about this, as the descriptions on different sites vary. This balancer is for two batteries, that is, for 24 volts, with the addition of a battery, the number of balancers must be increased. At 48 volts, three such balancers are already needed.

This balancer is not adjustable for different types of lead-acid batteries. There is an indication of operation, and an alarm relay, it closes if the voltage difference on the battery exceeds 0.2 volts. The price of this balancer just killed, at the time of this writing, the price on the site was 6220 rubles. For 48 volts, you need three of them, and in general you need to pay 18,660 rubles plus shipping.

Scheme of connecting these balancers to the battery. LED indicators and alarm relays:

Green: On when the battery voltage is over 27.3V
Orange: On when deviation is greater than 0.1V
Red: alarm (deviation more than 0.2V)
Alarm relay: Normally open contact closes when the red LED turns on. The contact remains closed until the deviation decreases to 0.14 V, or until the battery voltage drops to 26.6 V. The alarm relay is reset using a button connected to two terminals.

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Of the minuses, the price is too high, the balancing current is only 0.7A, and there is no possibility of customization for your battery type. There are better analogues at an affordable price.

Charge leveling device ELNI 2/12 for 2 batteries 12V

Found the same balancer. This is already a clearly active balancer, clearly superior to the first one in terms of balancing current, this one has a current of 5A compared to 0.7A for the first one. The price is also not small. 3600-3900 rub on different sites.

This balancer constantly monitors the voltage of the batteries connected in series, and equalizes the voltage by transferring energy between the batteries. And he does this not only during charging, when the batteries are almost charged, but constantly if there is an imbalance. And the balancing current here can reach 5A, which means that the balancer can cope with even a large imbalance in capacity.

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On this, on our sites, I did not find anything original that would not be available on aliexpress. Of course, there are many balancers, but they are all bought in China and are sold here at exorbitant prices. So why overpay if you can buy on aliexpress what our resellers offer.

Active balancer for 12v battery

On aliexpress, I found this balancer. This is an active balancer with a maximum balancing current of 10A. It monitors the voltage on series-connected batteries and equalizes the voltage by transferring energy between the batteries with an accuracy of 10mV. Each balancer is placed on its own battery, and the balancers are interconnected. You can view the description and buy here Balancer 12V. The price at the time of this writing is 1700 rubles, and this is not expensive for such a powerful active balancer.

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The manufacturer of these balancers produces several different types of balancers. On sale there are 2 volt balancers for individual lead-acid "cans". Also balancers for lithium-ion batteries at 3.6 and 4.2 volts. And balancers for 6 and 12 volt batteries. All balancers can be viewed here - Catalog of balancers 2/3.6/3.8/4.2/6/12 volts

Battery balancer for 24 volts (12*2)

I also found another popular on orders and cheap battery balancer. This is a balancer for two 12 volt batteries, you can install several if the system is 48 volts and higher. The balancing current is up to 5A, which is pretty good. The only thing I did not understand is whether it is active or passive, but judging by the size and the absence of a radiator, this is an active balancer. The price of this balancer is 1760 rubles, you can see it here - Double balancer for 12v battery

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The price is very attractive, and the balancing current is very decent 5A, so it will cope even with a large difference in capacity and voltage between the batteries in the system.

Balancer for (12×4) 48 volt battery

Here is another great active balancer for batteries, it is made in the form of a 48 volt block, that is, for four series-connected batteries. The balancing current is up to 10 amperes, and this is just fine, it will eliminate even a large imbalance. View the full description and buy it mono at this link on aliexpress - Balancer for 48v battery (12×4), price 3960 rubles.

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So far, this is all that I have been able to find, although of course not everything, but this is the main thing. There are controllers for solar panels with built-in balancers, but it is very expensive so far. There are chargers with balancing, but they are out of place here. There are all sorts of electronic circuits that can be made to work as balancers, there are options for making balancers yourself.

Peculiarities:

-Balance

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-Current control

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Pin Description:

4S Mode:	3S Mode:
"B-" - total battery minus "B1" - +3.7V "B2" - +7.4V "B3" - +11.1V "B+" - common battery plus	"B-" - total battery minus "B1" - short to "B-" "B2" - +3.7V "B3" - +7.4V "B+" - common battery plus "P-" - minus load (charger) "P+" - plus load (charger)

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Peculiarities:

-Balance Note: The HCX-D119 control board for 3S/4S Li-Ion batteries has a built-in balancer function. At the same time, in the process of charging the battery, the voltage on each of the cells is equalized to a value of 4.2V.
In order to use the voltage equalization function, you need to keep the battery under voltage of 12.6 / 16.8V for at least 60 - 120 minutes after the end of the active phase of battery charging. For the balancer to work, it is important that the voltage is not higher than 12.6 / 16.8V: if these voltages are exceeded, the controller will enter the protection state and the batteries will not be balanced

-Voltage control on each of the cells: When the voltage on any of the cells exceeds the threshold values, the entire battery is automatically turned off.

-Current control: When the load current exceeds the threshold values, the entire battery is automatically turned off.

- Ability to work with 3S batteries(3 batteries in series) The HCX-D119 controller is 100% compatible with 3S Li-Ion batteries (11.1V). To switch the controller to the 3S mode, it is necessary to bridge the contacts R8, and move the resistor R7 to R11 (R7, at the same time, remains broken) and close the "B1" pad to the "B-" pad

Pin Description:

4S Mode:	3S Mode:
"B-" - total battery minus "B1" - +3.7V "B2" - +7.4V "B3" - +11.1V "B+" - common battery plus "P-" - minus load (charger) "P+" - plus load (charger)	"B-" - total battery minus "B1" - short to "B-" "B2" - +3.7V "B3" - +7.4V "B+" - common battery plus "P-" - minus load (charger) "P+" - plus load (charger)

Now the market is full of chargers. Automatic machines and not, with and without capacitance measurement. Most chargers are universal and can charge elements of any chemistry. Lithium ion and lithium polymer are increasingly used in various devices.
Not so long ago, I converted the battery of a screwdriver to 18650 lithium-ion cells. I charge it with a Turnigy smart charger. But not everyone has this charger.

Required for assembly

I decided to assemble a simple charger with a balancer for lithium-ion. The charger has 3 identical independent channels. They can charge from one element to three. If necessary, you can add any number of channels. I have three of them, that is, 3S or 11.1 volts.
The case for the balancing charger is a case from a burned-out D-link router. If possible, take a larger case, it turns out to work very closely in it.

One of the main components are the power supplies of each channel. Their role is played by tablet charger boards, with an output of 5 Volts and a current of 1 Ampere (or you can buy it on Ali Express -.

Charge controllers are boards from China -. Each channel has its own controller. I have boards without protection, but it is not needed in this case. You can use controller boards along with connectors, I don’t have them on two, they were removed for other projects. The price of these modules is cheap. If you are engaged in finalizing devices on lithium-ion and lithium-polymer, then these controllers are indispensable.

Making a balancing charger

The charge controller boards need to be soldered to the outputs of the charging boards. It is possible separately. I soldered on thick cores from the power cable, so the design is more rigid.

The charge controller boards have LEDs that indicate the charge and the end of the charge. They need to be soldered. Instead of them there will be ordinary LEDs of different colors. They will be attached to the windows where the router's LEDs used to blink.

I soldered wires from an old computer hard drive cable to the LEDs. If there are LEDs with a common anode (plus), then it is better to use them. I didn't have any, so I used what I had.

In place of the old LEDs, solder cables with LEDs. In the photo I have a 3 mm green LED. I had to replace it, it turned out to be burnt, I did not check it before unsoldering.

For the back panel, you need to cut the overlay. In it we make cuts for the power switch and the output connector for 4 pins. The connector was removed from an old hard drive. You can apply any, for the desired number of pins, with a current of 1-2 Amperes.
The switch was removed from the old computer power supply. We fasten the overlay with two screws for rigidity.

We glue the output connector on epoxy glue or soda with super glue. For speed, I glued both one and the other.
Charging board with controllers, glued on thermal glue. But before fixing, I soldered the network wires.

One of the network wires, solder to the switch. The second, directly to the second wire of the power cord.

Now glue the LEDs. I glued it with hot glue, you can use soda with super glue.

Unsolder the output jumpers.
Plus the first controller on the first leg of the output connector. Minus it on the second leg and connect it to the plus of the second controller. And so on.

Roll up the body and set aside.

Let's make a wire for this charger.
I used two pieces of wire from a computer power supply. Soldered in order from the first contact of one connector to the contact of the second.

We connect the charger to the battery of the screwdriver (). The red LED indicates the ongoing charging process. At the end of the charge, the green LED lights up. Accordingly, the icons on the case light up: Wi-Fi, the second and fourth computers.

Here we have such a charger. The costs are minimal and the benefits are great.
With this device, you can charge assemblies on lithium polymers, those that modellers use in their vehicles. The main thing is to make the right charging wire.

A common feature of all lithium batteries is intolerance to overcharging and deep voltage drop. There are about 10 varieties of lithium-ion and polymer batteries using different compositions of active ingredients. All of them differ in the operating voltage range, but are demanding to respect the boundaries. Boards are electrical circuits embedded in the circuit to maintain the desired parameters, disconnect the lithium battery in case of its malfunction. For charging, balancing, discharge control and protection of lithium batteries, separate or combined boards are made, which are made on a solid substrate.

Why do I need a balancer when charging a battery? When several cells are connected in series, the voltage is summed up, and the battery capacity will be equal to the lowest of all cells.

To prevent overcharging the "lazy" bank, it must be disconnected from the power supply as soon as the charging voltage is reached on it. This will allow other cells to continue charging. A balancer is used to control the uniform charge. It must be included in a circuit with a series connection of elements. For a parallel connection, a balancer is not needed, where the charge level is distributed evenly, as in communicating vessels.

The balancer board can be made separately or included in the general protective circuit MBS for lithium batteries. The assembly is called a balancing loop.

The purpose of implementing the circuit is to prevent overcharging of individual cells. If a single and protected battery is used, it has an overcharge protection block.

Lithium battery protection board

Lithium batteries may catch fire or explode when overcharged or heated. When the voltage sags, it becomes difficult to charge. Each case of violation of the regime leads to an irretrievable loss of jar capacity. Therefore, any assembly of lithium batteries contains a protective board.

If unprotected elements are used, a charge-discharge controller is installed without fail. The PCB board is provided as a mandatory element in all batteries for household appliances.

PCB boards and PCM modules are not controllers, they do not regulate current and voltage. Their task is to break the circuit if a short circuit or overheating occurs. The modules allow a discharge of up to 2.5 V, which is dangerous. All protection modules are Chinese, products are produced in millions and it is unlikely that every microcircuit is tested. This is not a full protection, emergency.

For protection, MBS charge and protection boards are used, selected according to a double current load, with a built-in balancer. Lithium battery charging and protection boards are controllers that provide a 2-step process and provide the desired parameters. An indispensable condition for the second stage of charging is to turn off the power when the maximum operating voltage of the lithium battery is reached.

Lithium Battery Protection Board Schematics

All Lithium Ion and Lithium Polymer batteries and assembled batteries must be protected. To carry out charging in 2 stages, it is necessary to provide a constant current, constant voltage mode in series. Used in PCM or MBS board assembly.

Assemble it yourself or buy ready-made boards for connection, you choose. To charge lithium batteries, experts use Chinese products. They are ordered on AliExpress, with free shipping.

LM317

Simple charger, current stabilizer.

The setting consists in creating a voltage of 4.2 V by adjusting the resistors R4, R6. The resistance R8 is a tuning resistor. The extinguished LED will notify the end of the process. The disadvantage of this device is the impossibility of powering from the USB port. High supply voltage 8-12 V, the condition for the operation of this memory.

TR4056

Experts suggest that to charge a lithium battery, use the Chinese TP4056 board, with or without battery reversal protection. You can buy it on Aliexpress, the unit cost is about 30 cents.

The maximum current of 1 A is regulated by replacing the resistor R3. Voltage 5 A, there is a charging indicator.

Control stages:

• constantly, battery voltage;
• precharge if the terminals are less than 2.9V;
• the maximum constant current is 1A, when the resistor is replaced, the resistance increases, the current drops;
• at a voltage of 4.2 V, a gradual decrease in the charging current begins at a constant voltage;
• At a current of 0.1C, charging is turned off.

Experts advise buying a board with protection or an output contact for a temperature sensor.

NCP1835

The charging board provides high stability of the charging voltage with a miniature size of the board - 3x3 mm. This device provides charging of lithium accumulators of all types and sizes.

Peculiarities:

• a small number of elements;
• charges heavily discharged batteries with a current of about 30 mA;
• detects non-rechargeable batteries, gives a signal;
• you can set the charge time from 6 to 748 minutes.

Video

Watch the video for a full review of the TP4056 charge board