Are you sure you have a 20 amp fuse right now? That's too high. It should be more like 10 amps.
I only used a 7.5 amp fuse on mine only because I didn't have a spare 5 amp available. If you're drawing more than that to power an LED or charge a phone, you're doing something wrong. I ran 14-gauge wire from the battery and that is too small for 20 amps anyway.