I ran gp1100s NIMh in my 18th scales before I converted to lipos, but they were 1100s back then. What we were told to do, was charge them at 1amp and see how hot they got. If they were not too hot (temp > 125-130F), then could try 1.5amps and make same temp check. If OK at 1.5 could try 2amps. I never charged mine at over 1.5amps.

Approx charge time, at 1.5amps is less than an hour. If run down until they quit, expect 40-45min. If charged at 1amp, the time will be longer.