wiring power inverter to turn on w/ car?a

I have a 400 watt power inverter that I am going to use for my carputer. It is going to be hooked up to the secondary battery I have in my spare tire well. Problem is, if the car is turned off, the power inverter would still be on. I hate to have to turn the power inverter on and off every time I get in and out of the car. Can I use a relay from the ignition wire, or from the remote turn-on wire of my head unit, so that the power inverter will receive power only when the car is on or head unit is on? I already have a relay hooked up to the remote turn-on lead off my head unit to my 4 amplifiers, so could I simply run an extra wire off that to a relay for the inverter. Any suggestions?

Using a relay from the ACC wire is probably your best solution. Have you added up the current draws from each component yet? As you add more components, you should consider current capacity and draw on your electrical system. Good luck, DXAV

thanks. also, where is the best place to tap into ignition wire and what size fuse should I use (the inverter has a 40 amp fuse on it)

You can find an ignition wire by using a DMM, but you didn't mention the make/model, so we can't help you find the correct color wire. I would use another 40A, but up to 60A should be good. DXAV