Slo-V Flyer

You usually want to charge at or less than 1C for good Nimh cells, such as those IB4200s, unless you're racing and are willing to shorten the overall lifespan of the cells in favor of faster charge times, and better initial punch from a higher C rating charge.

I charge my 6-cell IB 4200 stick pack at 2.5-2.6 amps, or 2.9 amps in a "hurry." Takes about ~1.5 hours, because they are about 7.3-7.5 volts when the truck starts to just crawl or slow down big time.