I'm trying to install an aftermarket battery isolator (NOT a battery solenoid) into my 69 ford 4x4. It's a standard isolator with three terminals on top. The terminals are marked (1)Main (2) Alt and (3) Aux. How do I wire this up? I tried the obvious and got no power to the starter relay. What am I missing?

 

What do you mean you got no power to the starter relay? I assume that you have two cables coming off of the primary battery. 1 to started relay and 1 to isolator. The isolator uses the alt feed to switch the isolator open so that current flows to both batteries. So, unless the engine is running, you won't get power from the aux battery.

I prefer a constant duty relay instead of a isolator. It's easier to hook up. Take 10ga wire from battery to one of the terminals. Take a wire that is key switched hot to the engage post. Then 10ga wire from other post to aux battery. This way, the engine doesn't have to be running to connect the two battery. It takes very little juice to engage relay. Key is off, no power flows through relay. You need to use a constant duty relay, not a starter relay as s.r. are made for short periods of use and a constant duty is made to be on long times.

I am just kind of confused as to what you did. I can picture the isolator and all.

This probably doesn't help. SOrry, but maybe it will.

Good luck.

 

Hi Joe,

My isolator looks exactly like this blue one. And there is also some info on relays vs. isolators.

http://www.smithae.com/surepower.html

If you know how this style of isolator is hooked up could you walk me through the process? It seems obvious but...
And no, I do not have 2 "cables" coming off my battery. I have the primary battery cable going to the starter relay and that is it. The isolator does not seem to be set up for "cable" , which to me is a thick 0-8 gauge but for wiring, 10-22 gauge) I appreciate the help.

 

Hmmm, I dunno. It seems that hooking up the isolator shouldn't affect the relay. You should take the wire from the alt that goes to the main battery and connect it to the isolator. Then a wire from the terminal to pos post of the corresponding battery. As long as the grounds are still there, I don't see where the problem is. Sorry, maybe if I was there I could help trouble shoot with a meter.

Good luck.

 

I see you're referencing a surepower page -- is your isolator a surepower? They have installation instructions online (under the support section).

And don't be surprised by using relatively small wires for battery charging. Consider that batteries charge a *lot* slower than they can discharge. A typical truck battery can take 4-6 hours to fully charge, but can be mostly discharged in 5-6 minutes.

 

Thanks mzimmers. My isolator is not a sure power but they have lots of info i can use. I see they do have some specifics concerning wiring into a Ford so i'll check it out.