How long do you charge 8.4v1500MAH Ni-CD battery pack for airsoft guns?
About 2-3 hours
What would happen if you took a Ni-Cd AA700mAh 7.2V battery from an airsoft gun and replaced it with a higher mAh and V battery?
You could replace it with a battery with a higher mAh rating and the battery would last longer between charges. Increasing the voltage (V) may lead to better performance, but it could severely damage the electronics. I would highly recommend NOT increasing the voltage. You could get more than twice the lifetime with an NiMh battery instead of an NiCd. You will need an NiMh compatible charger. I would highly recommend NiMh over NiCd.