One the the battery packs of my one-and-only battery drill failed to charge.
I pulled it apart and found one cell had a very low voltage.
Given the age of the battery pack (about 10 years) replacement battery packs are not available.
I looked and looked on Ebay, Temu, Alibaba an many others. No Luck.
So I thought it best to replace all the cells with new higher capacity cells.
Unfortunately it is now illegal to post loose Lithium 18650 cells.
So I bought a cheap Battery pack which could be posted.
I rebuilt the original battery pack with the cells from the newly purchased pack.
As the new cells are "claimed" 5000 mA and the original were 1500 mA, I assumed the original charger would be useless.
The original battery pack did not have a BMS in the Battery but in the Charger
So I connected only the 2 power wires to the battery.
As you have probably guessed, when I connected battery pack to the drill nothing happened other than the LED light that points at the drill bit came on.
The Battery pack has 8 connection points the drill has 4 connection points.


The connections on the Drill are Power +&- and ID and TH shown in the photo>
There is 24k Ohm across ID and TH on the battery and 20k Ohm on the drill.
I thought I had the answer and dropped a 24k Ohm resistor across ID and TH on the battery.
Did nothing>
I have exhausted all guesses>
Polite suggestions/guidance please

Cheers

 

Replaced all the BMS wires and it now works.

 

INteresting and quite believable. Thanks for letting us know.

 

It would be nice to have a clear explanation as to what wiring is required for drill operation and that required for charging.