What are the 3 pins on FT BP 18 Li-Ion battery pack for ?

[threesixright]

Tried looking it up here, but found nothing...

Anybody have an idea what the 3 pins on the battery are for (the ones visible on top)? There are also 2  pins inside, these are the 18V pins.

I'm guessing it has something to do with temperature measurement, but not sure why 3 (often its just one).

Thanks!

// UPDATE added a photo

 

[AlexThePalex]

The 3rd pin is for communication between the battery and the charger.

There is a chip inside the battery that keeps an eye on critical data. For instance, it makes sure the battery never is depleted completely, this might destroy it. The communication between charger and battery makes sure it is always charged to the optimal condition for a long life.

 

[threesixright]

The 3rd pin is for communication between the battery and the charger.

There is a chip inside the battery that keeps an eye on critical data. For instance, it makes sure the battery never is depleted completely, this might destroy it. The communication between charger and battery makes sure it is always charged to the optimal condition for a long life.

Ah, thanks! And you have any idea what the others are for? Was looking for some pinouts, but no dice