Got on my 08 Nightster the other day to find a dead battery. First time this has happened and have never had a problem with it. No trickle charger but is ridden daily. Jumped it and rode around but wasnt taking the charge. Got a new battery and thought this was solved. Heard a sound like low level fuel injector operating with key off, killswitch on, but only for a moment. Next morning, new battery dead. Running on Screaming eagle heavy breather, Vance and Hines short shots, and a race tuner. Also 16" apes. Anyone have electrical issues with theirs? Looking for some advice. Thanks

 

More than likely you've got a charging system problem, bad stator, regulator, or both.
Get the battery charged, start the bike, and with the motor at a fast idle, measure the voltage from the + battery terminal to ground. You should have a MINIMUM of 13.5 vdc.