RE: Help with new 7.2v nimh 4200 mah packs?
Charge at 420 ma for 16 hours. Your charger probably has a 500 ma setting (.5amps) so use that. It may take 3 or more cycles of this to bring them up to full capacity. Discharge at 0.3C (1.2 amps) down to 1 volt per cell between forming charges.