How to deal with the voltage imbalance of polymer lithium battery pack?

Lithium polymer battery cells are usually used in a combination of series or parallel connections to form a battery pack. This way, we can harness more power for more time, and there are several benefits. However, to safely and efficiently use this system, the voltage must be balanced between every cell.

Otherwise, the battery cells will get inefficient charging, which may cause reduced capacity for the battery and introduce issues like overheating fires or explosions. If your lithium polymer battery pack faces a voltage imbalance issue, then the chances of such mishaps increase. So, in this article, we will discuss how to deal with such conditions to ensure safety and good performance.

Remove the Protective Board.

The protective board installed with the lithium polymer battery pack is often called the battery management system, and it is there to monitor every cell in the whole pack. It has duties like balancing every cell in the whole pack, whether it is being charged or discharged. Additionally, it adds protection to the battery pack from things like safe operational ranges, overcharging, over-discharging, etc.

Sometimes, this protective board goes bad, and that may lead to a voltage imbalance in the whole battery pack. The solution to this situation is to remove that board and try the battery with a new one.

How to remove the protective board, and what to do next?

If you want to remove the protective board from a battery, the first thing you must do is mark all the wire connections. It will be a good idea to take tape labels and carefully mark every connection, considering its potential direction and connectivity with the circuit. It is because these connections cannot be reversed or interchanged.

After all the connections are marked and noted, you may disconnect the connectors carefully and then remove the board. Next, you need to add a new protective board because using the battery without a BMS is not safe. When adding a new BMS, you need to carefully connect all the wires and connections in their right places.

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How can you tell if the voltage imbalance issue was because of the protective board?

If you were facing the voltage imbalance issue previously and changing the protective board solved the issue, then it was because of the circuit. However, if the issue stays even with a known-good BMS, it is most probably with the batteries.

Recharge or Replace Battery Cells.

If replacing the protective board did not solve the issue for you, you need to recharge or replace the battery cells. Below are all the steps that you must follow when working with the lithium polymer battery cells:

The Step-by-step Guide to Recharge lithium polymer battery pack Cells

Start by gathering all the essential tools you will need for the process, including safety equipment and a multimeter. Next, you may proceed with the following steps with your lithium polymer battery pack:

1.Physically inspect the whole battery pack for damage, leaks, or swelling.

2.Check the voltage of each cell, which must be around 3 volts.

3.Grab your lithium polymer battery cell and ensure that you get one that has balanced charging capability. Set the charging current according to battery capacity and start charging them.

4.Monitor the charging of each cell during the charging phase with a multimeter to ensure balanced charging. Remove batteries that show abnormal actions like overheating, smoke, or excessive heat.

5.Once all cells reach a high voltage point (usually 4.2 volts), you can carefully disconnect them.

6.Once again, check every cell for its voltage, and it must not be below 3.8 volts.

7.Reassemble and try using the lithium polymer battery pack.

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What to do if recharging these cells isn’t beneficial?

If recharging the bad lithium polymer battery cells wasn’t beneficial for your case, the last resort is changing the bad ones with new ones. However, it is important to balance out the voltage of new cells with old cells. If the number of cells you replace is more than the good ones, then an ideal solution will be switching to a whole new battery pack.

Recycle Batteries According to the Original Route.

When you replace some lithium polymer cells in your whole battery pack, you will be left with some bad ones. Those are not safe for use in any application now, so you must recycle them according to the original route. The right way of recycling these batteries is by disposing of them at a battery recycling facility. Remember that keeping these stored at home or throwing them in the trash is not safe.

Why is it important to recycle batteries

Here are some of the most important reasons why recycling batteries is important:

1.Environmental Benefits

Lithium polymer batteries are made from harmful chemicals that can cause land and water pollution if you throw them away in general trash. This pollution can be bad for aquatic life and plants since the chemicals can hurt whole ecosystems. When you recycle these batteries, the valuable materials are reused while the harmful elements are treated before disposing them of in the environment.

2.Economic Efficiency

Creating lithium polymer batteries is not a cheap process because the materials used for these batteries are mined from under the surface of the earth. When you recycle these batteries, most of the useful materials can be reused, which removes the need for mining and transporting the material again. Hence, the battery production price can be controlled.

3.Safety Benefits

Lithium polymer batteries, when not in perfect health, always impose significant fire risks. These batteries can easily get punctured, which can cause a fire and even an explosion. Moreover, if the lithium polymer battery leaks, its chemical can damage stuff in the surroundings. Recycling the lithium polymer battery will resolve all these issues.

Final Remarks:

An individual battery cell may not meet every requirement, and manufacturing a bigger cell for every use case is not efficient. That’s why we use generic-size cells in a combinational circuit to get the current and power that we want. However, when doing that with lithium polymer cells, we need to be extra careful about staying safe from voltage imbalance.

If you ever face this problem, you can get assistance from the guide above. It will help you take the right measures to maintain safety and efficient performance from your lithium polymer battery,