This is the isolator wired without the air filter box in place.

 

This picture shows the wire connections from alternator, second battery, and the external excitation wire and circuit breaker.

 

This picture shows the second battery and ground wiring.

 

This picture shows full view of complete setup.

 

This picture shows where I run the wire for external excitation. Sorry for all the posts, but if anybody is like me, pictures are worth a thousand words.

 

Thanks for all of the pictures. I have a tray and some batteries but I don't have anything wired up yet. I noticed that you have the Warn isolator, I don't know much about the different dual bat setups but can you switch between the two batteries? I'm not sure what the isolator actually does. I was looking at painless wiring's set up. They have an in cab switch for first, second, or both batteries. I haven't found anyone who carries this but I think that it is expenisive. Can yours do all this, or are you running both batteries all the time? Also how much was that isolator and wires? Thanks again for the pictures.
Michael

 

The isolator was bought through Warn but it is actually a SurePower Isolater (www.surepower.com). Click on Tech Support then click on Technical Bulletins and the first two (180012 & 180064) is what you want to look at for information about the wiring, etc.
The isolator will allow both batteries to be charged while the truck is running. When the truck is turned off the two batteries are isolated from each other. For example, the second battery I have is used to run my travel trailer on the weekends. As that battery is being used the main starting battery is totally isolated from the second battery and will not be drained by the second. The isolator is like a one-way valve. If my starting battery dies I can jump myself off with the other battery. And on the trip back home the second battery is charged back up by the alternator.
The isolator was around $65 and the wires were around $20. I think I could have used 8 guage but used 4 just to be on the safe side. I had to have the GM connector kit which I purchased at NAPA for about $25.
Hope this doesn't confuse you. Let me know if you have any other questions. I'll try my best not to confuse ya too much.

 

Say you have a CB or lights connected to the second battery, will they run with the truck running or only when off. Ideally I would want all my accessories to run off the second battery (and be able to use them when the truck is on and off), as well as be able to jump myself if needed.
Also, what is the GM connector kit? I have a '90 and therefore the different kind of alt. if that makes any difference.
One more thing, does the dash voltmeter read only the starting battery. I have plans for a winch and some other stuff and would like both batteries pushing while the truck is on but only that second when it is off, I think that you have said that yours will do that.
Sorry for me be confusing.

 

Anything you connect to the aux battery will run anytime with truck on or off. The GM connector kit is used if you have the CS or CS130-D alternator. The only way I knew which one I had was to look at the pictures on the two technical bulletins off of surepower's website. I had the CS-130D. I am not sure about the dash volt meter. I think it measures the output of the alternator not the voltage of the battery. Someone correct me if I'm wrong! I think the winch will only run off of the battery it is connected to. Remember, the isolator will only let the voltage go from the alternator to the batteries not battery to battery. I think for the winch to run off of both batteries you may have to get the switch your talking about.
Speaking of winches, have you or anyone else had any experience with the hydraulic MileMarker winches? I'm interested in getting a winch also and came across those. They only pull like 4 amps where as the electric winches pull something like 400 amps. Anyway, hope the info helps.

 

The voltmeter measures the voltage in the system. When your ignition key is on it measures whatever voltage there is in the system. If you choose not to start your vehicle then it is reading the battery. If you choose to start your vehicle you will probably be reading the alternator as long as the alternator is outputting a voltage greater than the battery. You need about a volt and a half more than the battery outputs to charge the battery or around two tenths of a volt per cell. In other words, you need around 13.8 volts to charge a 12.6 volt battery.

Since the voltage regulator is nothing more than a Zener diode (diode designed to work backwards) they are fairly good (usually two tenths of a volt) at keeping the voltage the same whether you are drawing 2 amps or 140 amps they are pretty easy to get to put out about 14 volts.


An alternator on all GM vehicles I've seen is directly connected to the battery. It goes from the alternator through a 10, 8, or 6 gauge wire down to the starter. From there it goes to the battery through a 2 or 4 gauge wire.

Therefore, as long as the main battery has more voltage than the auxilary battery and the isolator is on then current will flow.


A battery isolator doesn't provide the 200+amps of current a winch draws. Near stall a winch can easily suck 400 amps. You need to put a 0 gauge or 2 gauge wire between the batteries. If you want you can run the negative through the block and just put a Ford solenoid between the two positive terminals on the batteries.

 

And good thread! Thanks for the pics!