what do u want anyway?
using Lion because want fast ROF and compact size... and remember Lion only give you 11.1V no matter the battery is full or not
using Ni-Mh because is safely reason(well I don't use Lion myself) and I use 10.8V for my C8... and remember when you fully charge your Ni-Mh battery the output in the beginning is more then 13V (if you do have a charger with display it will say your battery is 13.XV) but when your battery half full... it will give you less then 10.8V and so on...
so as I said is really up to you...
Guns... lots of Guns...
