How to Balance a Battery Pack With USB or the Traditional Method - TP4056

Hi guys, today let's see together how to balance a battery pack through a very common micro-USB connector or with the traditional method

You can read this article also: https://www.pcbway.com/project/shareproject/How_to_Balance_a_Battery_Pack_With_USB_or_the_Traditional_Method_TP4056_e6832088.html

When charging a battery pack it may happen that, once charged, measuring with the multimeter there is a voltage slightly lower than what we expected (such as 41.5 V instead of 42V).

If so, then most likely, inside the battery pack, there is a cell (or several cells in parallel) that has a lower voltage than the others.

This is a problem because most of the BMS (i.e. the card that deals with the management of the battery packs) on the market stop charging the entire battery pack as soon as even a single cell reaches 4.2V and does not take into account the other cells that may still charge.

Conversely, if there is a cell in the battery pack that is at 50%, the BMS will cut off the power supply because it will detect that there is a low cell without knowing that all the others are charged.

First you have to remove the cover, the box or in any case the casing of the battery pack. Don't worry, if you've never done it, there's nothing to worry about.

You just have to pay attention to where you put your hands because the currents and voltages involved can be very dangerous.

Once you open the battery pack, you need to look for the BMS (Battery Management System) which is probably the only card that will be inside.

Once this is done it will be necessary to remove the 10pin connector called JST which has connected to it all the positives and negatives of each cell in series.

After that, through the use of the multimeter it is necessary to understand to which pair of pins the poles of the cell (which is made up of several cells in parallel) which is more discharged. To do this, you will need to insert the multimeter's leads from pin to pin with a one-pin pitch.

At the same time you will read on the tester the same or similar values ​​for each pair of pins and only when you reach the most discharged cell will the multimeter show a lower value.

The first method is the traditional one which is to charge the most discharged cell, balancing the battery pack, with the help of a bench power supply or any type of direct current power supply that can have a voltage value of 4, 2V.

Once you turn on the power supply and after setting it to 4.2V, just disconnect the banana connectors used before by the tester and connect them to the power supply.

I recommend, it is absolutely important that the two connectors are disconnected from the multimeter one at a time because if the two connectors were to touch, a wire of that section would melt in a fraction of a second.

Once this is done, all you have to do is wait for the battery to charge.

This was the most traditional method but also the most inconvenient because it forces you to have a power supply on for several hours which, in addition to being oversized for this job, is also very bulky and, if it has a fan as in my case, noisy.

So now let's see how to do the same job but in much much more efficient way.

The second method is to use a micro USB cable to charge the cell.

To do this we will use a micro USB module containing the TP4056 chip which, in addition to serving for this purpose, is also very useful for protecting and using single cells, protecting everything from overcharge, over-discharge, overvoltage, overcurrent and much more.

Our goal, however, is to use it only to load the cells, so we just need to simply solder two cables to pin B + and B- of the module and that's it.

Once this is done, if we try to connect a battery and the USB cable, as you can see from the photos, the charging of the cell starts and we notice it from the red LED that lights up.

Once we have ascertained that everything works correctly, all we have to do is insert the pins of the wires just soldered to the positive and negative of the most discharged cell of the battery pack through the connector in the BMS

Don't worry, if you get the polarity wrong you will notice it immediately from the burn that you will cause by touching the module.

In these cases, having around high voltage and ability to deliver very high current, I prefer to cover the module with a sheath so as not to run the risk of touching something to something else

Well, you will now have to wait for the light to turn blue and you are done balancing your cells in order to ensure much greater health for the battery pack. In a future article we will see how to add an automatic cell balancer to make it do this job.