Is the third wire positive or negative going into the battery on a Kawasaki 1100zx jet ski?

Most lithium ion battery packs I have come across, that typically have three terminals, have a terminal to allow the charger to do one of two things. This terminal will give the charger circuit a temperature reading, or, it will give it a reference to allow for both cells to have a balanced charge. On the battery I used for one of my projects there was a board that measured the voltage across 3 different cells to prevent over charging, over current, and undervoltage conditions. Without