ID's probably an identification or something.
So that another battery does not move in the screwdriver or charger, until this contact connects the battery electronics with the electronics of the screwdriver / charger.
Two of the same chips (one in the battery and the other in the charger) must communicate with each other, because at least for me, without this communication, the ID is not charged.
Yes, if I have, laptops with power supplies with such an additional contact have the same, a wrongly identified power supply, "not original", may lower our clocks or not charge the battery.
Added after 18 [minutes]: https://www.elektroda.pl/rtvforum/topic3797052.html I have + - and these ID and Christmas trees, no charging without this ID, the charger does not give.