I'm working on a little car based project, where I have an inverter protected by a 40a internal fuse. I need this inverter to only recieve power when the ignition switch is on (i.e. when car is running, so I won't kill the battery). Unfortunately, the only existing accessory power sources are protected by a fuse rated for only 7.5a. So tapping into these sources will ultimately result in a blown fuse.
Constant power sources have much less restraint (40-50a), but would normally require either manually unplugging the inverter, or wiring up a switch, that I'd have to manually flip to save my battery.
So, in the name of laziness (and the rule of cool) I'd like to create a switch that works automatically based on whether or not there is power to an accessory source. I've tried Google of course, but the closest I've gotten is either a transfer switch (not applicable - it's only being powered by one source) or an automatic switch based on whether or not the main source has power.
