The full charge on an E53 (and I would think the E70 would be not much different)is one can so you likely overcharged it for starters. +1 on you probably shouldn't be messing with it.

__________________
1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)