[rtomanek]

> Lithium ion batteries have a much flatter voltage curve - they basically give a stable 1.2V until they run out of juice and then drop rapidly.

Did you mean Ni-MH (and possibly Ni-Cd earlier)?

Lithium based rechargeables are usually not in AA format and the voltage is closer to 3.6V.

[p1necone]

Oops, yes. For some reason I thought rechargeables like enerloop were lithium but I was remembering wrong.