Best way would be to buy a 9.6v NiMH battery and try it on your gun.
If you get the same short battery life, then it's likely your motor, you'll have to buy a new one for $20-$60
At least if you change the battery first, you'll have an extra battery to use, and nobody can complain about that lol
It should be noted that any type of wall charger is looked down upon in airsoft, the majority of us have had bad luck with them. 7/10 problems new guys have are battery related, and 9/10 times it's their wall charger.
The iMax B6 charges both LiPo and NiMH, with you setup I would have stuck to NiMH batteries. You can get a good digital charger for $60, and you don't need any safeties or a MOSFET on your AEG in order to use them safely.
LiPo should only be used as a last resort if you need more power or higher energy density, because it IS more expensive to run safely than NiMH.