As instructed, I hit ‘E’ and selected my stack of batteries in my inventory to test the bionic out. It ate up all of my batteries. I guess I’ll be FULL for a very, very long time now? Realizing that, this might not be a bug, but everything is working as intended… If that’s the case, a prompt asking how many batteries to consume would be appreciated.
EDIT: To clarify, I didn’t have an Internal Battery installed when I tried the Battery System out. That might be the reason why it consumed 2300+ batteries at once, it’s impossible to refill 0 maximum power. Oh well, time to raid another electronics store…
EDIT II: Here’s a quote from the wiki concerning the Battery System:
A bionic which allows you to consume (E) batteries to generate power. Each full battery (100) regenerates 5 power when consumed.
This confirmed my suspicions, the Battery System consumed all of my batteries because there wasn’t any bionic power to recharge.