I bought a 12v plug in (female part that you plug a car charger into) that is supposed to be able to hook up to the battery. Once I hooked everything up, it had enough power to turn the light on on the car charger, but once I plug the charger into my gps the light fades out and my gps wont turn on. So I played with my wires to make sure they had good contact with the battery and a good ground but nothing helped. Turning the bike on didn't help either, so is there a relay or booster I'm missing?

 

Are both wires connected directly to your battery? A friend of mine has his direct to his battery with a switch. Also, a fuse is a good idea to run inline if you havent done so already. he has no problems with his. It sounds like a bad ground connection with yours though.