Anyone know where I can tap into my ignition 12v line? I want to set my relay to close when the car is running...

Thanks,
B

 

Behind the radio or the fuse block both have 12v ACC connections.

 

Yeah I was aware of those ACC lines...I tapped into them for my SWI-ECL interface adapter. But isn't the ignition 12v line only hot while the car is running? The ACC lines are switched on when you turn your key to the ACC position...but the engine's not actually on.

When I've heard others on the forum refer to ignition 12v line, I assumed they meant a line that was only hot when the engine was running and the alternator is cranking. Is this a correct assumption?

 

I am not aware of any such terminal - that is, one that is only ON when the engine is running, but otherwise not on when the key is in the ACC or ON position. Can you think of any feature or electrical accessory on the car that would require this? If so, find a way to tap it. Curious though - why do you want it?

 

I can't think of any like that either. What is the relay for?

 

You should be able to tap into something like the AC or window motor lines. Those only operate in the "ON" position. Why can't you just use the ACC line?

 

I want power to run to my 200w/25a inverter. But since I'm running the 12v straight off my battery, I want to use the relay:

a) to make sure I don't accidentally leave the inverter/PS2 on after turning off my engine.

b) to make sure the inverter is only drawing power while the alternator is cranking so I can be sure my electrical system/battery can properly handle the inverter load for whatever length of time. From what I've heard pulling load with your vehicle in the ACC position can drain your battery quickly.

This makes sense to me but I'm no electrical engineer. Am I just being paranoid?

-B

 

You'll be fine with the relay tapped into a 12v "acc" source. If you do it that way you'll have the option to use your invertor without the car actually running. You'd have to leave it on for hours to worry about draining the battery.

 

Sounds good...I doubt I'd be in there for hours. Guess I'll just use the ACC line then.

Thanks guys,
B

 

With just the PS2 and stock stuff running, it would take probably 30 minutes to an hour to drain the battery. I was working on the audio system one day in my car (3 aftermarket amps) and the drained the battery in under 10 minutes! Then I went out and bought an Optima Yellow top. It is awesome. So the lesson here is if you drain your battery, you have an excuse to buy a Kick As$ one.

 

Thanks, I guess I'll get a better battery if that happens to me. But I probably won't be playing too much without the engine running.

Thanks,
B

 

There are two types of switched power sources - IGN and ACC.

An IGN signal is hot when the key is in the 'ON' and 'CRANK' positions. This signal typically powers ECU and ignition/fuel type stuff.

The ACC wire is hot when the key is in the 'ACC' and 'ON' positions, but NOT the 'CRANK' position. This is all your accessories, and other things that you would not want drawing power when you are cranking the car (the more availible current the better chance the battery will start the car.

In a perfect world, you would power the inverter off of the ACC wire, but, as you said, it can lead to dead batteries from engine off use.

One idea would be to use the fuel pump relay signal to control your relay, then run the ACC voltage through the contacts of the relay. This would allow the inverter to only be turned on when the fuel pump is on, which is only when the engine is spinning (and for ~2seconds when you first turn the key to the 'ON' position to prime the system). The prime wouldn't mess anything up though, as the ACC would be off while cranking so the inverter wouldn't stay on.

 

Thanks a lot man. This is the kind of info I was hoping for.

-B

 

10 minutes???? Wow. I've run my system for over an hour and I'm only down to about 10.5 - 11 volts.