While using a Re-Battery to charge tools on your hotbar (Via Right-clicking), the tool finding function seems to get stuck if there's a fully charged tool already on your hotbar.
Case 1: 
(Both tools completely discharged)
Battery fills up each tool half-way.
Case 2: (Chainsaw 3/4th's charged, Mining drill completely discharged)
Battery will fill up both tools with 1/4th power, then stop. No amount of right clicking will get battery to charge the drill up.
Case 3: 
(Same as Case 2, except I've removed the Chainsaw from the hotbar.)
The mining drill now charges.
Case 4: (Chainsaw fully charged, Mining Drill partially charged)
The mining drill also charges.
Something tells me there's a 'While moving from left to right in the hotbar array, if valid IC2 tool is fully charged, then drop out of loop and return 0' business going on.
Edit: Using mod_MinecraftForge 1.3.3.12