Dual Battery Setup using OEM parts?

[Tall56Dog]

Hello, new guy here.

2020 Tahoe LT Z71 Midnight Edition, 5.3, 4wd

Truck isn't a PPV, but seems like this would be the best forum to ask about an OEM Dual Battery Setup.

I know there are many options, Straight Parallel, DCDC Charger, Aftermarket Isolator, but I want to keep everything clean using OEM parts.

I've already bought and installed the new battery tray and hold down, and a new Interstate AGM battery.

From the GM Parts Direct site, I'll also need Fuse Box 23239735, Negative Cable 84354710, Relay 12135194, and Positive Cable 84355668. Parts total about $250.00 with shipping.

I don't think this will be too hard to do, but I was hoping someone with a 2015-2020 PPV could post some pics showing how all the cables are run and relay connected.

Thanks!

 

[Tall56Dog]

Schematic of the dual battery setup for 2015-2020

 

[Doubeleive]

I haven't seen any write ups on it but it looks like this is the basic diagram, not sure how the isolation relay #9 ties in but the "fuse box" #5 is the 2nd battery positive connector with 100 and 50 amp fuse's, the negative cable #7 goes from 2nd battery terminal to block next to the temperature sensor, the positive cable #8 goes around the engine bay outside edges. #6 is the fuse box cover

 

[Tall56Dog]

I haven't seen any write ups on it but it looks like this is the basic diagram, not sure how the isolation relay #9 ties in but the "fuse box" #5 is the 2nd battery positive connector with 100 and 50 amp fuse's, the negative cable #7 goes from 2nd battery terminal to block next to the temperature sensor, the positive cable #8 goes around the engine bay outside edges. #6 is the fuse box cover
View attachment 361271

Thanks Wes!

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[BlackYukon]

Hello, new guy here.

2020 Tahoe LT Z71 Midnight Edition, 5.3, 4wd

Truck isn't a PPV, but seems like this would be the best forum to ask about an OEM Dual Battery Setup.

I know there are many options, Straight Parallel, DCDC Charger, Aftermarket Isolator, but I want to keep everything clean using OEM parts.

I've already bought and installed the new battery tray and hold down, and a new Interstate AGM battery.

From the GM Parts Direct site, I'll also need Fuse Box 23239735, Negative Cable 84354710, Relay 12135194, and Positive Cable 84355668. Parts total about $250.00 with shipping.

I don't think this will be too hard to do, but I was hoping someone with a 2015-2020 PPV could post some pics showing how all the cables are run and relay connected.

Thanks!

Feel free to document your progress on here. I'v been wanting to do the exact same thing, Just a simple, clean, oem looking dual battery setup.

 

[swathdiver]

@intheburbs Bill has done this on his GMT900s and documented it. If you can find the posts across the internet you can then apply it to your K2 platform.

 

[Tall56Dog]

Feel free to document your progress on here. I'v been wanting to do the exact same thing, Just a simple, clean, oem looking dual battery setup.

Just ordered all the parts, no turning back now.

 

[Tall56Dog]

For anyone interested in doing this, I've learned a couple things. First, before I forget, in addition to the parts I've listed above, you'll also need the positive battery post cover. Part # is 22945779. It has been discontinued, but you can still find them on Ebay. You'll also need the battery tray, and battery hold down, and bolt, parts # 2 and 3 in the pic in my first post. Part # for tray is 23231841, the hold down is discontinued, but you can get them on Amazon.

I realize this isn't for everyone, there are less expensive ways to do it. I just wanted to stay as OEM as possible. I mostly accomplished this with one exception. This is for my 2020 Tahoe, depending on your year, your configuration might be different, although I'm pretty sure 2015-2020 stayed the same.

I have no connection with them, but I like buying from GMPartsDirect, good prices and fast shipping.

The one exception I mentioned above, is that my truck didn't have the wiring connection for the Isolator Relay. GM must have decided to remove that wiring at some point unless it was for a PPV. What I ended up doing is just removing the relay and isolator from the new wiring harness, and then I bought a VSR (voltage sensitive relay) from Keyline Chargers. I actually like this better than the OEM relay and isolator, it's a cleaner install, and supposedly there is no parasitic voltage draw from the OEM Relay. So, if you decide to do this, you may not want to buy the "Accessory Power Relay", part # 12135194. I have a brand new one if anyone needs it as I can't return it.

Overall, I'm really happy with how it turned out. It's mostly OEM, with the Isolator being the only exception.

When you do this, the new positive battery cable (84355668) has both the positive cable for the fusebox, and the positive cable for the aux battery tied together in the same loom. You'll end up removing your existing positive cable and not reusing it.

If anyone has any questions, I'll try and answer as best I can.

I ended up making a bracket for the Keyline Isolator instead of mounting it directly to the firewall.

 

[Tall56Dog]

More pics.

 

[Tall56Dog]

This is not my pic, but the parts circled were replaced by the Keyline VSR.

 

[Denali Brad]

A couple of questions for you if you are still around. Lookin at doing pretty much the same thing. When using the Keyline VSR, was the rest of the wiring in the loom (other than the the positive cable) not used? It appears the VSR only needs a ground connection? My intended use is a backup battery in extremely cold situations, and I was also thinking of using the Cole Hersee 200A Isolator to be able to connect the two batteries together via a switch when needed. Thoughts?

 

[Tall56Dog]

A couple of questions for you if you are still around. Lookin at doing pretty much the same thing. When using the Keyline VSR, was the rest of the wiring in the loom (other than the the positive cable) not used? It appears the VSR only needs a ground connection? My intended use is a backup battery in extremely cold situations, and I was also thinking of using the Cole Hersee 200A Isolator to be able to connect the two batteries together via a switch when needed. Thoughts?

If you buy the OEM setup from GM, both positive wires are in the same loom, you'll end up not using your stock positive battery cable. It would be nice if you could just buy the longer cable that goes to the aux battery by itself, but you can't. The VSR just hooks inline with the positive cable running to the aux battery, you basically just use the VSR instead of the relay, and yes, other than that, the VSR just needs a ground connection. There is a ground connection on the firewall that I used. One thing to think about though, I don't think the VSR allows reverse flow back the the starting battery. So, to use the aux battery as a backup, you would need to hook it to the starting battery via some jumper cables. In my case, I'm using the aux battery for a winch, so I don't care about backing up the starting battery. I carry a Jump Pak in case I ever get stuck with a dead starting battery.

 

[Bubbaduss]

How did you tie down the battery? I picked up a battery tie down block at advanced... But the aux battery tray has no theaded holes. On the one side I "could" run the bolt through, but tightening that up would be a PITA. And technically you need a clamp on the opposite side... Did you guys drill and tap the plate?

 

[Sparksalot]

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[Tall56Dog]

How did you tie down the battery? I picked up a battery tie down block at advanced... But the aux battery tray has no theaded holes. On the one side I "could" run the bolt through, but tightening that up would be a PITA. And technically you need a clamp on the opposite side... Did you guys drill and tap the plate?

You have to replace the existing tray with part # 23231841. The existing tray isn't designed to hold a battery.

 

[Sparksalot]

If you buy the OEM setup from GM, both positive wires are in the same loom, you'll end up not using your stock positive battery cable. It would be nice if you could just buy the longer cable that goes to the aux battery by itself, but you can't. The VSR just hooks inline with the positive cable running to the aux battery, you basically just use the VSR instead of the relay, and yes, other than that, the VSR just needs a ground connection. There is a ground connection on the firewall that I used. One thing to think about though, I don't think the VSR allows reverse flow back the the starting battery. So, to use the aux battery as a backup, you would need to hook it to the starting battery via some jumper cables. In my case, I'm using the aux battery for a winch, so I don't care about backing up the starting battery. I carry a Jump Pak in case I ever get stuck with a dead starting battery.

Do you happen to have the GM part number(s)?

 

[Tall56Dog]

Do you happen to have the GM part number(s)?

Part #'s are in the 1st page of this thread.

 

[Sparksalot]

Part #'s are in the 1st page of this thread.

Not sure how I missed that before.

 

[Bubbaduss]

You have to replace the existing tray with part # 23231841. The existing tray isn't designed to hold a battery.

My tray is exactly that #... I had to install the battery hold down block before putting the tray back in as there didn't appear to be any threaded receiving point...

I have questions regarding the battery side of things.

What did you change on this box? If anything

You have to replace the existing tray with part # 23231841. The existing tray isn't designed to hold a battery.