I just recently received a 9 cell 27++ battery for my T510. I've never seen this kind before - it attaches to the bottom of the laptop. If I try to use it instead of a 55++ main battery, the laptop receives no power.
Do I have to have both batteries in place for it to work?
The system can be powered from just the slice battery as long as the slice battery switch is "on" and locked to the bottom of the system. If the switch is off, the slice battery will still be seen by the system, but will neither draw power from it, or recharge it when plugged in.