Why won't your motorcycle keep it's battery charged?

It can be any number of problems...my security system was draining my battery. Start troubleshooting the problem by pulling out your fuses one-by-one and seeing which circuit is responsible. It will show up on an amp meter connected to the battery when you plug the fuse back in. You could have a hot wire grounding out, a faulty switch, a relay that is stuck or even a demon-possessed alarm system. Two other circuits that generally don't have fuses are the starter and the headlights. You can test them by disconnecting the cables that go to them.

Then, again, it could be something as simple as a bad battery. If you put a fast-charger on the battery you may have fried it. Get it tested before you do anything else.