I have an electric J3 cub which has a 400 size electric motor using a 8.4v,1100mah NiMh battery pack. Connected is a ESC (not sure of rating).

Could someone please tell me whether it would be possible to use a 2500Mah pack instead of the 1100Mah pack without causing damage to the motor or speed control ?

Also what would the effect be of charging the 2500Mah pack with the 1100Mah pack's charger, the charger is a slow charger taking about 3 hours to charge the original pack.

Any help wouldbe appreciated. Thanx

yes , you can use the 2500 mah pack,but i will be heavier.the charger is ok but it will take more than twice as long to charge it

if you have an 1100 mah nimh pack now, that is probably AA (or similar) sized cells, and the 2300 might be C or sub c, my point being there is a substantial weight difference, and your flight time, assuming you get off the ground, might not be higher. (you now have to run at full throttle 100% of the time just to stay aloft, whereas before you could have throttled back)

Anyway, try some of the 1600/1650 8 cell nimh AA packs. Fairly light and should give you a little more time.