I'm in a quandry I've purchase a bunch of 1.2 aaa nimh's off ebay and used a 9.6v 8 battery holder from mouser.com to make my own battery packs for the pico tiger moth...It barely provides enough power for level flight let alone take off....The 8 cell 1/3 a 9.6v pack from a sapac pitts when attached gives double the thrust and power...I've tried everything to figure out why...The voltmeter reads 10.5 v on both! What do you think the problem is? the home made pack should give the same performance but it's useless and the plane is totally under powered...Am I missing something? Are the chinese batteries not correct for rc electric planes

The first question is:
What is the mah of both packs?

Bill

Not all aaa cells can deliver the amount of current that you need to power the motor. Measuring voltage tells you that the cells can out out 1.2 volts each (for example). But some low-cost cells cannot put out enough current (measured in AMPS). One way to see this is to measure the voltage on the battery terminals while the motor is running. A "good" pack will not drop all that much. A cheap pack will show less voltage when the motor is running.

9.6v from chinese batteries is the same as 9.6v from japanese batteries. The issue is that the cheaper cells do not have the same output current as the more expensive ones. Discharge rate is what is hanging you up.