the batts can be upgraded to 3600ni-mh packs for extra punch and life ..but u need a mite need a different charger to charge ni-mh ..the highest you can go on ni-cd is 2400mah but these will still be a hell ov a lot better than the ones u have motors r also upgreadable if ya decide u want owt or just prices on stuff let us know bay be able to do you deal