well i think it can be done because i got some wire and a zz batt and i put them together and it gave my a longer run and charg so i think it can be done.
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Mr.M new and improved no lie'in
yea it can ive done it before. and for adding another battery(dual cell) just search it so many links or goto rcmod.com i think it is they have many great mods to do. good luck