Protection Circuit Modules (PCM) for Li-Ion and Li-Pol batteries

NEW TECHNOLOGIES STELS LLC supplies protection boards (PCM modules) only as part of batteries.

Using Li-Ion or Li-Pol batteries without a PCM (which controls the voltage of each cell in a battery pack) may cause a possible fire or even explosion during its charging or operation. That is why the PCM is the most important component of any Li-Ion or Li-Pol battery.

While engineering and designing a battery most of the developers and further producers make a rough mistake in order to protect it. They apply one of many typical specialized chips that protects the battery by limiting the minimum and maximum voltage of the whole battery, regarding it as a battery pack of several connected cells.
When monitoring the voltage of the whole battery pack, the voltage of each cell changes over time (depends on the number of charge-discharge cycles). This can be because Li-Ion cells have different actual capacity and different internal resistance in one delivery batch. The difference in values might be from 2 to 15%, depending on the Supplier of the cells.
When operating the battery such difference between cells’ capacities leads to unpredictable events. You may confront the situation when the voltage of the whole battery is fixed 12V by the voltmeter, but the real voltage of the cells can be as following, for example:
6V + 5V + 1V = 12V or
11V +1V +0V = 12V, etc.
It is known that Li-Ion cells, as well as Li-Pol cells are not allowed to exceed the voltage more than 4.2V (in reality - 5-6V). This requirement is written in technical documentation of any cell manufacturer.

If the required voltage is higher, it can cause a fire or an explosion of the cell or even of two cells. The usage of batteries not provided by protection board is especially dangerous because the chance of having a battery explosion arises much more after several cycles of charge-discharge. Thus, the consumer confronts a similar situation during the battery operation.

We used to install protection boards in all Li-Ion and Li-Pol batteries assembled by our company.
Our protection boards vary and differ in the current permitted to charge and discharge the battery- from 4A up to 40A and in the quantity of protection channels (corresponding to the number of cells connected in series).

The structure of the protection board and the algorithm of its operation is described on the example of a single-channel protection board (for 1 Li-Ion or Li-Pol cell).

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