Hi,
I tried a search in this forum and came up empty. If this topic has been covered before, I missed it.

Is the only benefit to charging above the 1c rate simply shorter charging times? I just bought a new charger that capable of charging at up to 20 amps. I have some 4700-5300 mah 70c 2cell packs that are rated at up to 2c charge rate.

Will they last longer if I stick to 1c charge rates?

Do packs somehow perform better if you really zap them, i.e. 3c and 4c charge rates, or do people do this simply to save time?

Yes, some guys "zap" them. This seems to be pretty common in 17.5 blinky class where everyone is on a pretty level playing field (or are supposed to be) and are looking for that little edge. Funny thing is I've heard a million times that someone actually improves on lap time as the race goes on because power is a little too much at the start. I never charge above the recommended rate, I've got extra batteries so I'm never in a hurry for a fresh one. And yes, it will definitely shorten the life of your battery

Yes your packs will last longer if you charge at 1c.

High charge rates is a safer way to warm your packs. The trick is to discharge 20+ then charge at 20+. This will lower IR which in turn increases punch. The problem with this is it doesn't do any good unless you run the pack after is finishes its charge. You lose your advantage if the pack sits and cools down. Don't use a heating blanket either. Ive seen many packs puff and a few catch fire because someone used a heating plate or blanket.

http://www.rctech.net/forum/electric...-more-now.html

Thanks for that link.