I have a 2008 sportster XL1200 low. Battery voltage drops from 13v to 5v when I plug in the 30amp main fuse. Tried unplugging several things, still have the problem. Any thoughts?

 

I would first check the battery and starter solenoid cables to make certain they are not damaged or grounding. Then I would test for "Shorts to Ground" http://www.cycleelectricinc.com/

 

Why are you doing this, are you having an issue?

 

I had my bike on a trickle charger for a few months and when I came home and tried to start it all the lights went out and nothing would work, that’s when I started checking the electrical and discovered the voltage drop.

 

Forget the voltage drop for the time being, you have a dead battery.

First you need to charge the battery fully and have it load tested (it sounds like it is kaput).

While the battery is out, clean all the battery cable connections.

 

Have the battery load tested. A battery can read at spec with no load, then as soon as even a minor load is put on it, the voltage drops.

 

If you had the battery on a trickle charger [not a battery tender] for a few months,you have ruined your battery.

 

x2!!!!

common mistake trickle vs tender