PB2SL charge and discharge balancing technology

XTAR Light

Apr 26, 2010
As you know, all batteries in parallel should have the same voltage and capacity. If two batteries with different voltages are connected in parallel, they are forced to become the same. The higher voltage battery will rapidly charge the low battery. And it discharges itself in the process. The greater the voltage difference, the more current will flow between them. And the more heat will be generated. The batteries might be internally damaged or there exists fire risk.

Then, some customers asked this question. If they put two different 18650 batteries into xtar PB2SL for charge or discharge, is it safe? Actually, the PB2SL doesn't make parallel charging or discharging directly, when a voltage difference (0.5V±0.05V) is detected between two batteries. Instead, the system autonomously starts the battery balancing mechanism. It ensures two batteries reach voltage equilibrium before connecting them in parallel. It avoids uncontrollable cross-channel discharging between the batteries. This could lead to overheating, damage, or even fire.

To charge two 18650 batteries in PB2SL, it prioritizes charging the lower-voltage battery. Once the two batteries are detected with same capacity, they will be charged in parallel way. When the PB2SL is used as power bank, discharge priority is given to the higher voltage battery. Until it reaches voltage balance between the two batteries. Then they are connected in parallel for discharge at the same time.