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Battery protection board not working correctly.


New Member
Hi gurus. I bought this little battery protection board and wired up 2 18650 batteries per the attached diagram but get no power at the "P" side. When I attached the batteries at the P side, the B side has power. Can any guru tell me what I'm doing wrong please? Screenshot_20210223_223255_com.lazada.android.jpg


Well-Known Member
Most Helpful Member
You may have to connect the P side to a charger temporarily to get the electronics to switch on.

Also note that the board appears to provide undervoltage / overvoltage protection, but not balance - you must also have balance for the cells to properly charge as a pair, otherwise charging will stop as soon as either cell reaches maximum voltage.

It's OK as it is if you are using a battery holder and charging the cells separately.

Nigel Goodwin

Super Moderator
Most Helpful Member
As already mentioned, you simply need to apply power (8.4V) to trigger the protection circuit to life.

We replace a LOT of faulty cells at work, and very often they don't work with new cells fitted and you need to give them a quick 'kick' with a PSU.

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