Yes Kris that will work, in fact it will work great if wired correctly.
Some comments from above statements.
Kris, I cant imagine that to be right on all the semis and stuff they always run atleast 2 sometimes 4 batteries to get em cranked over and burning. I dont think they run battery isolators.....
Information from the relay supplier.
So why do you need a relay isolator to run two or more batteries? Isolators serve two purposes. First they allow a set amount of current to travel between the positive terminals of two or more batteries. So for instance if a system was set up with a relay isolator that is rated to handle 200 amps this means up to 200 amps of current is able to flow from one battery to another. Second, all batteries have a different potential voltage so this means if two batteries are connected together without using a relay isolator the batteries would actually drain each other until they are both completely discharged (two completely dead batteries). Since each battery would have a different potential voltage they would push and pull on each until there is no energy left. This is where the relay comes into play; the relay will ONLY connect the two batteries together when triggered to the ôONö position (while the car is running). So when the relay is switched ôOFFö the batteries are disconnected and no energy will be flowing between them (when the car is off).
The batteries will not go dead overnight, unless one is dead already, but over a few days you will notice a voltage lost.
I would just tie both batteries together.
That way, you have less of a percentage of draw from the batteries & they last longer.
Also, you will most likely have the engine running, so the alternator can charge for recovery.
If the engine is not running, you darn well want both of those batteries to power the winch. You would have to put a switch to engage it & the solenoid itself tales precious electricity when you may need it most.
I have been wiring up boats this way for years & have better results with a large bank as compared to 2 - 1/2 sized banks. 1/2 the discharge depth (percent of battery) & 1/2 the cycles.
Ed
I to have been wiring boats for more years than I care to remember. In all those years I have never tied two or more batteries together without using a isolation switch. Your statement
"the solenoid itself tales precious electricity when you may need it most." is not factual. Very little current is use to engage the relay/solenoid, surely not enough to affect the winch.
In Kris's case using the above relay is the preferred way.
The only thing I would do different, is to run a wire from a +12V always hot source to a switch instead of ignition power. This way you can uncouple the batteries at anytime.
If it were me I'd switch off the main battery while winching. This way you will not spike the alternator or other electronic in the truck that's connect to the main battery. But that's just me and that's why I run a hydraulic winch.
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