I was curious, so I checked my chargers, my Team Checkpoint 1030 - 0.35v, iCharger 3010b - 0v, GT Power A-6-10 - 0v, and my Hyperion 0610iNet - 31.45v.
None have ever failed to charge anything asked of it, 2S thru 6S life and lipo, nimh.

If you want a real answer, post your quest in the battery and charger thread on RC Groups, I've see some Hyperion reps answer ques over there -

http://www.rcgroups.com/batteries-and-chargers-129/