I own a Powabyke , which is probably similar. The two halves of the battery case are held together with deeply recessed phillips screws. First remove the battery fuse if fitted. Then remove the strip which con tains the output terminals, two screws. Split the case. When rebuilding, take care to not overtighten screws that screw into plastic, or you will strip the threads. Avoid short circuiting battery terminals and/or wiring. Hope this helps.