Case issue aside…how much extra battery life do you need? How long do you need to be away from power? At a minimum, the BP3T will give you 6-7 hours of usage when doing general stuff and full screen brightness.
Would double the current life you’re getting now be enough? i.e. 2 x BP2T?If not then get a BP3T instead as it lasts 1.5 times longer than a BP2T.