Fixing Dual Battery Setup (1 Viewer)

[TheBestCow]

Hello, I bought this 2000 LC this weekend as a secondary vehicle, an education platform for me and my family to begin wrenching (I have 2 kids under 7 that want to help), and for a weekend/vacation cruiser to the mountains and beach.

To be clear: I know absolutely nothing about electrical, so I may say something a scared novice would say... but that's the point. Here to learn.

Previous owner didn't do any of the electrical, the previous-previous owner did.

It's a dual battery setup somewhat similar to @KlausVanWinkle's setup in the FAQs in that:

• It has dual batteries
• The batteries are in the same location as the Klaus post
• It uses thick gauge wiring

But... I think that's where the similarities end.

There is no solenoid that I can find, no battery monitor like the T-MAX kit, the positive red wiring goes down behind the ARB front bumper, and -- my biggest concern -- no fuses on the wire between the positive main and positive aux posts.

There is a Stinger SGP32 200 Amp Battery Relay Isolator mounted near the aux battery... but it has nothing save a ground wire coming off of it. It looks like there is a connector broken off at one of the posts, but no positive cables running to it, no other cables running to it. There is also a line that runs from the aux positive back to the rear right of the car where there is a fuse box installed and a 12v port for a fridge.

Back to my biggest concern: the lack of 200 amp fuses on each end of the positive cable connecting the two batteries. I've read that if there is a short in a line, you want a fuse close to each end to avoid having a live arc welder in your hood, causing a fire, etc. Other internet searches say some vehicles that come with dual battery setups from the factory don't have fuses either.

1. How fearful should I be of the lack of fuses? I don't know what the odds are of a short (since the truck has been driven this way for a while), nor do I understand when a short is most likely. Essentially, is this safe enough to park in my garage? (Rather ask a basic question that not...!)

2. Is there a way to utilize what I currently have -- current wiring, current unused Stinger SGP32 -- to achieve something similar to the T-MAX setup?

3. If no to question 2, do I just buy the T-MAX kit, but instead of completely removing all of the wiring, just modify what I have (after disconnecting everything, cutting the positive to positive cable to include the fuses, connecting the two pieces to the solenoid, adding the monitor wiring)?

I can provide photos a bit later. It's currently pouring outside (no leaks!).

Thanks... off to buy some hood shocks!

 

[saucebox]

Not totally related, but some of the off-the-shelf kits can be configured without fuses also. It's usually recommended for winch wiring since that draws so much current (and when you need a winch, you sure don't want fuses popping).

Here's the National Luna kit instructions: https://www.nationalluna.com/wp-content/uploads/2017/09/NL-SP-Charging-Kit-DIY-2018.pdf. Configuration 7 shows one of the ways of hooking it up, without fuses.

Adding fuses would be easy enough even if not strictly necessary, and going through the system to make sure there aren't any opportunities for the wiring to be loose (and rubbing on something) is probably a good first step.

 

[TheBestCow]

Not totally related, but some of the off-the-shelf kits can be configured without fuses also. It's usually recommended for winch wiring since that draws so much current (and when you need a winch, you sure don't want fuses popping).

Here's the National Luna kit instructions: https://www.nationalluna.com/wp-content/uploads/2017/09/NL-SP-Charging-Kit-DIY-2018.pdf. Configuration 7 shows one of the ways of hooking it up, without fuses.

Adding fuses would be easy enough even if not strictly necessary, and going through the system to make sure there aren't any opportunities for the wiring to be loose (and rubbing on something) is probably a good first step.

Interesting, but it is still connected to a solenoid even without fuses? Again, ignorant on electrical, but would that provide any protection?

I think at bare minimum I would need to move where the positive to positive cable is as right now it goes down behind the ARB bumper and back up, and there are definitely some places where it is rubbing on metal.

I guess I'd need to see if any other systems recommend fusing with a winching setup?

 

[highkick05]

Took me about 2 months to figure out all of the wiring in my rig after buying it (1998 FZJ105R in pic left). UHF / Spot lights / Red arc dual battery / Aux wire to the rear anderson plug / ARB fog lights and indicators . Fmd was it confusing. Turned out the UHF and ARB Sahara bar fogs and indicators were getting powered off the dead 2nd battery which had me baffled as. Probably why the UHF died in the end.

Best you rip everything out and do it properly. Sounds like a pile of garbage like mine was.

 

[TheBestCow]

Took me about 2 months to figure out all of the wiring in my rig after buying it (1998 FZJ105R in pic left). UHF / Spot lights / Red arc dual battery / Aux wire to the rear anderson plug / ARB fog lights and indicators . Fmd was it confusing. Turned out the UHF and ARB Sahara bar fogs and indicators were getting powered off the dead 2nd battery which had me baffled as. Probably why the UHF died in the end.

Best you rip everything out and do it properly. Sounds like a pile of garbage like mine was.

I'm definitely going to be spending some time with a multimeter, me thinks. Rig at one point had a roof rack and LED light bar up there, but it's been removed... don't think the wiring has.

Not sure about a whole pile of garbage, just trying to make sure I understand before I park it indoors. The Luna link above is kind of interesting considering no fuses but with a solenoid.

Looking at WARN's website, they have a dual battery isolator recommend parts section that includes the T-MAX, Painless Wiring, and a TOW READY Battery Isolator Solenoid for $17.99.

From Warn:When running a dual battery system for auxiliary lights, RV's and winches, Tow Ready's battery isolation solenoid will switch off the 12 volt feed from the vehicle's battery when the ignition is turned off, preserving the life of your vehicle's battery, ensuring your vehicle will start.

From 4WP:Cadmium plated isolator with terminal nuts and lock-washers. 3 terminal isolator for metal frame ground systems, 4 terminals has insulated ground terminal for use with fiberglass or other non-conductive materials. Isolates starting battery, provides secondary battery current for auxiliary power and full time charging of both batteries.

Would something like that + fuses work? Or is that the same thing as the Stinger SGP32 that is already in the vehicle but lower amp rating (a comment on the 4WP page says "can handle 80 amps continues, 100 amps intermittently and 160 amps spike"?

 

[saucebox]

Interesting, but it is still connected to a solenoid even without fuses? Again, ignorant on electrical, but would that provide any protection?

I think at bare minimum I would need to move where the positive to positive cable is as right now it goes down behind the ARB bumper and back up, and there are definitely some places where it is rubbing on metal.

I guess I'd need to see if any other systems recommend fusing with a winching setup?

Yes to the solenoid, fused or not. But their diagrams will of course feature their parts. You could absolutely replace their solenoid with another of your choosing.

Definitely address the routing.

Looking at WARN's website, they have a dual battery isolator recommend parts section that includes the T-MAX, Painless Wiring, and a TOW READY Battery Isolator Solenoid for $17.99.

Would something like that + fuses work? Or is that the same thing as the Stinger SGP32 that is already in the vehicle but lower amp rating (a comment on the 4WP page says "can handle 80 amps continues, 100 amps intermittently and 160 amps spike"?

They should be similar. Do you know why the Stinger is disconnected? Could be as simple as a part failure that got bypassed. 80A continuous is a lot of current, and I haven't heard of a ton of solenoid failures (here on ih8mud).

Another easy bit of research is to jump into the tech forums here. I think there's one for electrical, and you should be able to see all kinds of homebrew setups very very similar to what you have already. With a little bit of work and possibly a $20 solenoid, you can probably have it fixed (and understand the system front to back in the process).

Maybe start here: Power Systems

 

[suprarx7nut]

I would draw out a wiring diagram on paper so you understand how it's wired up. Then add in a fuse anywhere you will draw less than 300 Amps (and match the fuse as close to the top end of your use as you can - IE don't use a 250A fuse where you expect to draw 60A at most). A winch will not (generally) use a fuse, but rather a disconnect switch. The disconnect switches can handle 500+A with the proper wiring.

I bought a car with a visually rough 2nd battery install. Before I parked it in the garage, I disconnected all the wiring to solar and to the 2nd battery because I couldn't verify it (it was just too cluttered to tell what was going where). Now it's all cleaned up I now how it's wired and where fuses are.

 

[CORunner]

One of the good sources I found for understanding dual batteries setups was marine/boating websites. It isn't exactly apples to apples in setups, but a lot of the principles are the same. Usually boats have a small engine starting battery and a very large bank of house batteries.

This website goes over wiring for BlueSea ACR, but some useful info in there.

Making Sense of Automatic Charging Relays - Marine How To

 

[hoser]

Alternatively (though more costly), you can take a different approach with a Redarc DC-DC charger. A better set-up when running dissimilar batteries... otherwise, that AGM aux battery never gets 100% charged. See diagram below.... run the winch off the start battery. Also allows for solar charging should you go that way in the future as well as charge a lithium aux battery.

On sale, 20% now.

 

[vman07]

I'm using circuit breakers in my dual setup. Trip the breaker and the entire aux side is disconnected from the starting side. On my rock crawler my starter is run through my aux fuse box which is ran through a circuit breaker. Trip the breaker and the truck won't start, kinda like a poor man's kill switch...

 

[TheBestCow]

Got the second battery completely disconnected from everything for now (and of course, the positive to positive cable off of the main/starter battery, too). Only two other wires are added to the positive on the main battery right now, both are fused. I think one is headunit and the other is the front IPF spotlights... but haven't verified yet.

Everything is zip-tied away where it can't bump into either battery, not planning on driving it, but enough to get it parked in my garage for the evening. Plan is leave it there while I fix other things, namely a small sunroof leak I discovered today as it was pouring cats and dogs outside.