i was told one time that you can charge your battery to the amperage as the mah on it, without damaging it. forgive me for the lack of technical terms and correct me if i'm wrong.
if for example you have a 9.6v 2300mah nimh you can push 2.3amps into it
or a 9.6v 3200mah nimh you can push 3.2mah
obviously this is done with a good smart charger. i have done this with every battery ive put on my smart charger, and i've only had one battery get fairly hot and it was a battery that we were fairly certain was toast anyways