My truck is factory dual battery dual 100amp alternator.

I would like to add an additional frame mounted battery to run aux items like an inverter and winch. No power from 3rd battery going to starting system.

What I would like to do is mount a battery tray to the frame rail at the rear of the truck. Winch power would be cables running front and back with quick disconnect.

To charge I'd like to use the factory trailer power wire. It is adequate gauge, already in place and I have no use for it with the trailer I tow. How would you recommend tying into the charging system so there is no chance of the aux battery drawing the main batteries down?

See if you can get a wiring diagram for the TP2 dual battery setup on the gassers. The second battery is isolated and used for the things you mentioned. There's a simple factory relay setup to charge the battery.

DEWFPO

Did they use that same setup '97 and earlier? I've got the wiring diagrams for them.

Did they use that same setup '97 and earlier? I've got the wiring diagrams for them.

I don't know the answer to that question. Mine's an '05 and I think the NBS trucks (2000+) are set up the same way. Can't speak for the OBS trucks.

DEWFPO

Please post somethin' here if you get this worked out. I'd like to do a similar setup, with an aux. battery mounted in the bed with the inverter.

I prefer using a battery isolator. Easy to wire. Check out this link:

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

Also check out
www.surepower.com

battery isolator is simple to install and fairly reliable. We use them on the farm on our service truck for example so we can run the slip tank with the truck off and still start the truck after.

I prefer using a battery isolator. Easy to wire. Check out this link:

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

Also check out
www.surepower.com (http://www.surepower.com)

From their site:

The difference in whether to use a battery isolator or battery separator will depend on whether your alternator has internal or external voltage sensing. Many of the newer alternators are internal sensing and so cannot be used with an isolator, because of the loss of approximately 1 volt across the diodes, In these cases you would use a battery separator. The experts at Smith Auto Electric can determine which unit you will need.

I could ASSume, but it seems dangerous. Can anyone tell me whether my truck's alternator has internal or external voltage sensing?

Check out this application guide: http://www.surepower.com/pdf/isolatorguide.pdf

Then go ahead and call surepower's toll free number. They will help you determine exactly what you need. They are the experts.

Check out this application guide: http://www.surepower.com/pdf/isolatorguide.pdf

Then go ahead and call surepower's toll free number. They will help you determine exactly what you need. They are the experts.

:thumb: Looks like a 16023A will fit the bill. I'll call 'em as soon as they're open.