Buy a smart charger, problem solved.

For a more detailed explanation, review internal resistance in batteries :D At the same time, learn why bigger NiMh batteries push harder :D

But yeah, smart charger, man... you'll get sick of forgetting your battery on the charger real quick.

Just saying that overheating will do nothing for lifespan
 

Sorry my mistake, I must have been asking the wrong people :D

•The charger’s “manual” says 0.3C to 1C.
•Servaas Products says 0.5C charge, 0.25C discharge, although I have no idea how reputable they are.
•PowerStream kind of says 1C, at least in a “smart charger” like this one that (I think…) senses temperature as well as voltage drop. (But maybe I’m giving this Maha charger too much credit? Will have to look back at the docs.)
•Panasonic says 0.5C to 1C (PDF). I actually like this document: specifies charging behavior from start to finish, and it agrees with other things I found.
•Duracell says 1C, or 0.5C to 1C.

Starting to see a trend here.

Duracell seems to primarily recommend 1C rate, watching temperature, but at the bottom they also list other methods, including less than 1C charge rate with basically the same termination conditions.
•Isidor Buchmann says 1C more or less. “Nickel-based batteries prefer fast-charge.”


From what I know of nimh chemistry "and it's limited" I would not go over 0.8a (this is not RC you don't need it in the next 5 minutes anyway)

Cheers

Pete

Slight highjack... I bought an Imax B6. I am charging a 8.4v 1600mAh NiMH and a 9.6v mAh NiMH. The charger has an variable output of 0.1-5A. I understand the math for charging duration. What is a healthy output to charge at?

1 or 1.5A for mini packs.

Well I don't always do it but if I need a quick charge I won't hesitate to charge at 2C. Usually I'll go .8C to 1C.