Using a relay to isolate batteries?

nd4spd18 · Post by **nd4spd18** » Mon Apr 02, 2007 6:21 pm

I have searched several different forums for info about this and have found nothing. What I am wanting to do is run a regular automotive battery in the front to start the car, and a Kinetik 2400 in the back for the audio system.
Now, I know that an isolator would allow me to do this, but the diodes cause voltage drop. So would it be possible to use a high current relay to connect the rear battery when the ignition is turned on, and disconnect it when turned off.
I know that different types of batteries should not be mixed because they will "fight" each other when not being charged by the alternator. But, would it be ok to have them both connected when the alternator is charging them? :help:

Bwcad1 · Post by **Bwcad1** » Mon Apr 02, 2007 6:32 pm

ur talking about a serious relay. i don't know if they make them that high. y do you care about voltage drop so much? if your competing which is usually the reason either is gonna hurt you.

Ryan from Ohio · Post by **Ryan from Ohio** » Mon Apr 02, 2007 6:42 pm

Unless you plan on sitting around with the car off bumping I wouldnt bother.

Depending on the size needed, Ive heard of some Jaguar Relays being used that can handle upto 240 amps I believe. They were not cheap however, over $200.

nd4spd18 · Post by **nd4spd18** » Mon Apr 02, 2007 7:18 pm

That's what I want to be able to do. I know I could just use an isolator, but I have seen relays big enough and got this idea.

So I guess what I really want to know is: can I connect an autozone battery to a Kinetik battery when the alt is charging them, and not have any issues?

Fishy · Post by **Fishy** » Mon Apr 02, 2007 7:57 pm

Here ya go:

http://www.boatownerswarehouse.com/brow ... ,12365.htm

Just don't leave it on "all" when the ignition is off and make sure you have it so your alternator is charging your starting battery when its NOT on "all". You wouldn't want your starting battery to go dead on ya while you're driving.

If you want to make it idiot-proof just use a simple high current switch like this:

http://www.boatownerswarehouse.com/brow ... ,12363.htm

The nice thing about the first option is you'll be able to start your car with the kinetic if you find yourself in a pinch.

cargodz · Post by **cargodz** » Tue Apr 03, 2007 12:00 am

Here ya go... Battery isolator from PAC, 200amp/ 300amp surge the PAC200 & SPR200 http://www.pac-audio.com/products/productsCatagory.asp?mmSearch=Battery%20Products

Post by **GlassWolf** » Tue Apr 03, 2007 9:31 am

There are different types of battery isolators. not all of them are diode banks. The problem with a relay is you're not going to find one of a high enough rating to handle an audio system's current draw adequately. Also, you may see a bit of current loss through heat, but you won't have a voltage drop across an isolator, as the battery's voltage is what sets the rails anyway, and as long as the battery is charged properly, your amps will always see the proper voltage.

read the section on http://www.bcae1.com on battery isolators and charging systems. It's very informative.

Post by **GlassWolf** » Tue Apr 03, 2007 9:33 am

also, yes with the isolator, the two batteries won't see eachother, so the autozone and kinetik should be fine together.

nd4spd18 · Post by **nd4spd18** » Tue Apr 03, 2007 10:27 am

Ok, I guess I will just use an isolator. I read the Bcae1 page, thanks.

But now I have another question: I am looking at isolators and found that some of the say they can't be used with Delco CS series alts, which is what my truck has. Then there are others that say they are designed for CS alts, and those have a terminal on them that has to be connected to the ignition wire.

Does anybody what what the deal is with that, why a regular isolator won't work?

smoker · Post by **smoker** » Tue Apr 03, 2007 12:28 pm

yea, if you have a gm and use the wrong type of isolator you will fry your voltage regualtor and it will suck