Dual batteries

[1989GMCSIERRA]

I found a C3500 with dual batteries so I took the driver side tray and brackets cause I was gonna do a dual battery set up. Never did it. A single battery was all I ever needed.
If you find on make sure it has the charcoal canister bracket. I just took everything.
If you look at the driver side fender area in the engine bay you’ll see the dimples where the brackets bolt to the fenderwells.

if I was gonna do a dual battery set up I would do it as a relocation to the back of the truck fir weight transfer.

 

[El Tigre]

You must be registered for see images attach

Starting battery is divorced from rest of system until 13.5v. is reached. It can't get run down. There's also a multi-battery switch that can connect/disconnect either ,or both if desired for doing work ,anti-theft ,etc....

 

[Duck-Wurk]

2 D3400 & 3/0 Trystar Truck Came With Battery Tray Though

You must be registered for see images attach

 

[dmhscorpion]

Never have had an issue with a single battery cranking up my 350 (now 383) or my 8.1. Factory gear reduction mini starters on both.

On my Express van the auxiliary batteries (2 x 6 volt Trojan deep cycles in series) are tied into the main battery via a 4 gauge cable and heavy duty relay. Use the deep cycles for a house battery for all the 12 volt accessories and my 3,000 watt inverter. The deep cycles are also connected to the deep cycles on the nose of my travel trailer with a forklift battery connector and 4 gauge wire. I have a 6,000 watt inverter in the travel trailer.

My Tahoe has a deep cycle battery on the driverside tray that is charged with its own 145a AD244 alternator. Runs an inverter and my music. Tahoe also has a forklift connector on the back bumper.

Why a deep cycle?

 

[dmhscorpion]

Interesting topic. I've kicked around the idea of adding a second battery, but basically put it out of my mind when I got the storage box instead.... stole it out of my dad's old truck before it was sold

I would have thought my truck would have had the 2nd battery from the factory since it has the snow plow prep package according to Compnine, but it does not.... only one.

I've heard many times that replacing both batteries at the same time is important, because one can run the other one down if one won't hold a full charge.... the good one keeps trying to charge the other one. I have no idea how valid this is, Though.

I've also been under the impression that they were normally wired with some kind of isolatior, but maybe that's only typical when adding a second battery later.

For now my solution is to keep a battery charger on my single battery, to keep it topped off. I'm not driving the truck right now.

I can tell you from experience, having matching batteries is important. I have ran dual batteries in my '99 Tahoe for 13 years. The Tahoe would sit sometimes sit at an airport for several months. Being somewhat frugal, I put a new, but a low quality, battery in as the secondary battery. It is wired through a constant duty relay, controlled by a double throw center off switch on the dash. One position connects both batteries together, the other position only connects both batteries if the ignition switch was on. (powered by the main battery.) If you don't use a switch to manually connect the batteries, a dead main battery will not activate the relay and it won't make those nice noises you anticipate when you turn the key. I went through several AC Delco main batteries until I changed both batteries at the same time. I have had no issues since.
I own several mountain top Microwave communications sites that are powered by a battery bank and charged by solar and backup generators. If we have a weak battery in a bank of batteries it will pull the whole bank down, due (usually) to the internal resistance of the suspect battery. At $600 for each 2 volt battery, we keep a close eye on them...

 

[SUBURBAN5]

I can tell you from experience, having matching batteries is important. I have ran dual batteries in my '99 Tahoe for 13 years. The Tahoe would sit sometimes sit at an airport for several months. Being somewhat frugal, I put a new, but a low quality, battery in as the secondary battery. It is wired through a constant duty relay, controlled by a double throw center off switch on the dash. One position connects both batteries together, the other position only connects both batteries if the ignition switch was on. (powered by the main battery.) If you don't use a switch to manually connect the batteries, a dead main battery will not activate the relay and it won't make those nice noises you anticipate when you turn the key. I went through several AC Delco main batteries until I changed both batteries at the same time. I have had no issues since.
I own several mountain top Microwave communications sites that are powered by a battery bank and charged by solar and backup generators. If we have a weak battery in a bank of batteries it will pull the whole bank down, due (usually) to the internal resistance of the suspect battery. At $600 for each 2 volt battery, we keep a close eye on them...

Wouldnt mind seeing pics of the set up. I'm getting ideas of what I would do. Everybody seems to have different hook ups for dual set ups

 

[SUBURBAN5]

2 D3400 & 3/0 Trystar Truck Came With Battery Tray Though

You must be registered for see images attach

Now that some thick guage wire.lol Your driver battery just hooked up to the passenger battery?

 

[Trenton]

I replaced the starter, added another battery, and converted to top posts using ACDelco PG34 batteries. I used 1/0 cable, hand crimped all terminals, and added shrink wrap to protect the exposed wires at the crimps.

It starts at least 10x faster, and it worked just as well when the temp dipped here in the high rockies!

Sorry for not having better pictures, I took these pictures over a year ago and my truck is 1200 miles away with my family in Texas.

You must be registered for see images attach

You must be registered for see images attach

 

[ccreddell]

Something I just discovered on my 99 2dr Tahoe is that it came stock with dual battery trays. But the drivers side tray is filled with the electric smog pump. But the little foot is there to retain the battery. And it fits with the stock washer reservoir. In my 90, I converted over to the radiator mounted washer bottle so I could run the underhood tool box, so I know it will fit. Im not using my smog pump atm, but, I am thinking of running dual batteries so I can run a refer in the back for overlanding. And, like mentioned above, you should always match batteries. If you dont, the weaker one will always drag down the stronger one.

 

[MRAJB]

I am also considering dual battery setup since I have a plow. Would love to see some photo of how to install. And where the second tray goes.