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Given is an 18650 Li-ion battery with built-in protection PCB. It is used to power an electrical load and can be charged by a dedicated Li-ion battery charger. In the schematics below, the battery is charged when the switch is closed which corresponds to connecting the charger to the battery.

As the Li-ion battery features a protection PCB, it will detect if the battery gets shorted and will cut-off the current flow. Usually, the battery protection PCB can be resetted by connecting the charger to the battery. However, I found out that for my case the battery protection PCB does not reset when connecting the charger to the battery unless the electrical load is disconnected from the battery. That makes sense as the battery protection PCB seems to monitor if the electrical load that caused the short is still there and only resets if it is removed. However, is there any way to reset the battery protection PCB without disconnecting the load? Because in my case, the electrical load cannot be easily disconnected and it's not the electrical load where the actual short of the battery might occur, but it might occur externally, directly shortening the battery for some milliseconds. I tested this for different batteries with protection PCBs with the same result (Keeppower and Panasonic). I know that it's the safest solution to avoid external shorts in the first place. But I'm also curious about this question from a technical point of view.

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ Consider using a large capacitor to power the load for a fraction of a second while you disconnect the battery to reset its protection. \$\endgroup\$ – Brian Drummond Jul 3 at 15:49

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