Doh! Any Ideas?
 

Ok... So i decided to try the dual cell mod on one of my zips today... I unsoldered the black wire, resoldered to the positive on the 2nd battery, soldered another length of wire from the negative back to the spot where the black was originally.

I then go charge it up... double charge in fact, and then try to make it go... Well it inchs along just barely. Any ideas with what the problem might be? Would I need to make a seperate charger? is it a problem with the battery? Any help is appreciated

there's already multiple threads on this, do a search. Anyway, the stock charger won't charge two bats, unless you break..er um fix it.