Hello All! Hope all is well with everyone!
I recently opened up a old cordless drill that was lying around for years. I stopped using it because it just wouldn't charge up.

I noticed that the battery pack inside had 3 wires instead of 2 wires, coming out of it.
The wires were going from the battery pack, in to the drill trigger mechanism as seen in the pictures.

Can some one please tell me what the purpose of the 3rd terminal on the battery pack is? The third terminal is marked with a red arrow and is much LESS wider than the other 2 terminals. The third terminal had a white wire coming out of it.

Thank you for you replies!

 

The third terminal is likely a connection to a temperature sensor.
The temperature is monitored during charging to prevent overcharging which will destroy the batteries.

 

The third terminal is likely a connection to a temperature sensor.
The temperature is monitored during charging to prevent overcharging which will destroy the batteries.

Really?! You mean I could probably salvage a temp sensor from that black box?!!! I am opening that thing, right now!! Thanks for your reply!!

 

The black box with the red trigger is the power switch.
The temperature sensor (thermistor) is in the battery pack!