7.4 Lipo aren't bad to use, not strong enough to fuck the weapon (maybe the contacts but you still should be fine with 2cell). If you are not specifically looking for higher firerate and trigger response, a NiMh would be easier until you read on LiPo and understand the (small) risks involved with them batteries.
LiPo can be charged and discharged without any memory effect, but going too high or too low will either kill the battery (no more power) or kill the battery again (resulting in a nice little fire). Going below a certain voltage (between 3.1v and 3.5v, depending on who you ask) will damage the capacity of the battery to stock power permanently.
No matter the choice, I'd recommend a smart charger, and get one that can charge all common type of hobby batteries (at least nicd, nimh and lipo), so charging batteries will be easier, and if you change for LiPo later, you can keep the charger.
K3vX | Airsoft Gunsmith/Gun doctor in training.
Feel free to contact me in your preferred language and I'll gladly answer.
Last edited by K3vX; March 31st, 2013 at 15:50..