What does Balance Current drain means on the charger?

And what should the minimum be on the charger to be used by off-road track to s4 batteries, and races

With Lithium cells it is important that the voltage of a cell is not going beyond a limit, in a serial connection with not that equal cells there is always one that will reach the limit 1st. If that is not taken care of then the voltage will go higher than wanted. A balancer will switch on a small load on that cell and drain some capacity while still charging the other cells.

Most simple chargers have a 300mA balancer current but with higher current chargers you have a higher current or even adjustable balance current.

There is no specific current but balancing will go quicker with higher balancing currents when charging with higher charging currents.

Balance current becomes very important as your packs age, for example if you charge at a 2C charge rate then it will take about 30 min to charge a newer pack. Over time the IR fades differently between the cells and the balance current picks up the slack for the mismatched IR between the cells. If your charger has a low balance current rate then it won't keep up with the mismatched IR and will take significantly longer than 30 min to charge the pack. I highly recommend investing in a charger with the highest balance current you can afford. This will drastically reduce your charge times for aged batteries which will save you time/money in the long run.


I discuss other things to consider when selecting a charger here:

• Which charger is the best?