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Overmind said:
Today's power tools are very complex.
Inside a Makita battery there are 8 (14.4V) or 10 (18V) 18650's, and the BMS.
Here is there thedesign flaw: the BMS draws power only from the first pair of cells. If you leave it sitting for a while, the BMS will deep discharge that first cell to zero, while the others remain charged. Result: dead battery.
If you put it in the charger, the charger will mark the battery as bad (the data pins I was mentioning) and it's unusable forever.
I was trying to reply to your post on a different Makita battery thread you've posted on but it was more than 3 months old and I couldn't post on it. ? So I hope its OK to post it here.
Did anybody figure out yet how to reset or disable this on the original makita boards? Without replacing the boards with the not great ones that can be bought online.
I have a load of the batteries that won't charge and show 0V on the battery pins but if I measure the voltage on the cells they are perfectly fine and balanced with each other.
This is really "stupid" from Makita (I know it makes perfect business sense) because it forces people to dump these batteries and buy new ones or those who dare to open them up and replace the boards, but loose the balancing capability while charging.