Originally Posted by jgrebe
My guess is the battery. Connected to an alternator a battery will take a surface charge but won't have any real depth of charge. As soon as the inverter comes on it drops the voltage below its set point and trips out. Test it with a battery tester (the load type that you can barrow from a parts store) Alternatively test the inverter on a known good battery. If it works its the battery
Will do, I can't see it being the battery though to be honest because it's a Optima Yellow top less than a year old that has never seen any load aside from charging a laptop through the inverter and some LED lights/tiny fan. Will check it out though thanks. It also runs the lights/fan fine they are hard wired to battery.