ground invertor only when car is on

**TaylorH** · 11-12-2006, 04:50 PM

ok, i am not sure if this is possible, but lets give it a whack...

I currently have my invertor hot wire (+12) spliced into the hot wire of the cig lighter, and the ground is securely grounded to the chasis. This works ok, but when i have the defogger on and am idling, sometimes the invertor beeps, and thats obnoxious. so i was thinking i would like to get some FAT guage wire and run a lead straight off the battery (fused of course) to the positive term on the invertor.

I would like the invertor to only be on when the car is on though, so is it possible somehow ground it through something that only works when the car is on?

i'm mildly new to the inner workings of car electronics so be gentle

**deanthom** · 11-13-2006, 09:47 AM

I think that switching the ground would be a bad idea, because it may find a ground some other weird and wonderful way and smoke something important, like your headunit. Use a relay to switch the +12V power to your inverter, a normal 30A automotive relay should do. Connect the relay coil to the ACC circuit so it's only on when the car is on. Also, see my reply to your other post about the low-volt problem.

**evandude** · 11-13-2006, 10:17 AM

yes, you always want your ground to be the highest quality connection possible, so running it through a relay (or some other circuit in your car, which would be even worse) would be a big no-no, when you could just as easily switch the +12v instead.

**TaylorH** · 11-13-2006, 12:40 PM

hrm... i have no experience with relays and how they work, but what you say sounds like it is exactly what i want!

would an autoparts store be the best place to pick up a relay? is it pretty much just 3 "pins" one for voltage in, voltage out, and the third for the ACC line to tell it when to complete the circuit?

**deanthom** · 11-13-2006, 07:57 PM

A bit about relays: http://www.the12volt.com/relays/relays.asp

Heres a guide on using automotive relays to do various things: http://www.the12volt.com/relays/page5.asp#rtol

You can get them from a parts store, radio shack, or maybe even walmart(?)

**jnorion** · 11-13-2006, 09:58 PM

I don't know exactly how your inverter works, but on mine I extended the hard-wired power switch and added a relay into the circuit there. The inverter already has a relay built into it to switch the high current wire from the battery so I just worked with the low level switch.