Parked F2 1993 to work on it. Accidentally left lights on for 5 minutes? 10 minutes? Not sure. Just turned key off when noticed, no big deal to me. Barely cranks the next day. I buy a trickle charger/maintainer and charge just enough to get it to start, then I drive for about 15 miles, stop at brothers house, turn engine off, try to turn back on, nope. Has even less charge than I started with. I jump it with my brothers truck and cables (hey I had to, the house was locked and he was gone). I ride home (4 miles), turn bike off, try to start again and the battery has even less charge. The cooling fan ran, but nothing from the starter. It was nearly dead. Any idea? Don't these things charge like a car battery while driving? It does seem like a cheap battery (china). I know it's not good jumping with a car, hopefully I didn't Fck up the Voltage regulator rectifier. I have the battery charging now.

 

Let the battery fully charge and see what happens. After its charged, put a voltmeter across the battery at 5k rpms and see f you have 13.5v to 14.5v.