Partial charging – what is it?

It is now known that in most lithium batteries (with the exception of LiFePO4), the cell / pack life cycle can be drastically increased by not charging / maintaining the cells to 4.2 V, but instead charging to a lower voltage, eg 4.1V. In this way, manufacturers of electric cars can get 5-8-year warranty on batteries, which usually when charging up to 100% reach only ~ 500 cycles.


Most chargers for electric vehicles do not have the option of setting the charging voltage and operate in one charging mode up to 4.2 V / link. As a result, it gives the maximum possible range of the battery but at the expense of reducing the life of the battery at each charge. In many cases, this means a battery replacement worth 2000 PLN every 1-2 years, when with proper maintenance you can extend the life of the battery to about 4-5 years !!! In fact, the further away from full charge, the closer to the long battery life.

Thanks to our charger it is very easy to choose the battery level for a given percentage of full capacity – you can set the charging to 90% and 100%. And so in the case of a 20Ah battery, regularly overcoming trips requiring less than 18Ah, we only need to charge the battery to 90% (up to 18 Ah). At the moment when we want to get a full range of batteries or allow BMS to balance cells, this is the only opportunity to take advantage of recharging up to 100% (many cheap BMS chips start balancing cells with maximum battery charge).

Partial charging and cell balancing

The only disadvantage of continuous partial load is that large parts of low-cost and low-quality BMS circuits start the balancing process at the closest maximum battery level. This means that when performing partial charging, the cells will not reach the maximum voltage, and BMS will not start the cell balancing procedure. Over time, the voltage levels on individual cells can go away and the battery will have less capacity. To avoid this, it’s enough to occasionally (once or twice a month) charge the battery up to 100% or use high-quality, tested, programmable BMS systems that can start the balancing procedure even at 50% battery charge !!!