Practical repurpose of second battery ?

I was looking for some advice or ideas on what could I do with the second battery on a Tahoe PPV. Does anyone know what relays/modules are routed to the secondary battery (if any) from the factory?

I figure its intended use from the factory would be for upfitting, to power emergency equipment without drawing on the main battery but obviously in the civilian sector that isn’t really needed. So I’m wondering what should I do with it

Thinking about maybe doing a sound system, like amps and subs and wire it to the second battery?

What about setting it up as a ‘reserve’ battery in case the main battery fails.. Would that be possible? practical?

Would appreciate any input

PPV_2018 said:

I was looking for some advice or ideas on what could I do with the second battery on a Tahoe PPV. Does anyone know what relays/modules are routed to the secondary battery (if any) from the factory?

I figure its intended use from the factory would be for upfitting, to power emergency equipment without drawing on the main battery but obviously in the civilian sector that isn’t really needed. So I’m wondering what should I do with it

Thinking about maybe doing a sound system, like amps and subs and wire it to the second battery?

What about setting it up as a ‘reserve’ battery in case the main battery fails.. Would that be possible? practical?

Would appreciate any input

Click to expand...

You might look through the GM Upfitter guide to see if they were available with the isolation relay, and what the number is for it. In the gmt900 PPVs they were available with and without the relay. Thecopcar didn’t have one while theothertwin did. If I remember it was a common multipurpose relay used in a lot of GM vehicles. It had ignition sense to isolate the second battery when the engine was off.

PPV_2018 said:

I was looking for some advice or ideas on what could I do with the second battery on a Tahoe PPV. Does anyone know what relays/modules are routed to the secondary battery (if any) from the factory?

I figure its intended use from the factory would be for upfitting, to power emergency equipment without drawing on the main battery but obviously in the civilian sector that isn’t really needed. So I’m wondering what should I do with it

Thinking about maybe doing a sound system, like amps and subs and wire it to the second battery?

What about setting it up as a ‘reserve’ battery in case the main battery fails.. Would that be possible? practical?

Would appreciate any input

Click to expand...

commonly they are just connected in parallel

Mine is set up so the primary passenger side battery is used for every thing. The second drivers side battery is only used for starting if the primary is dead. There is an isolation module that connects both only when engine is running for charging. If I need to start from the secondary battery I toggle a switch. Look up Hellroaring battery systems.

Sparksalot said:

You might look through the GM Upfitter guide to see if they were available with the isolation relay, and what the number is for it. In the gmt900 PPVs they were available with and without the relay. Thecopcar didn’t have one while theothertwin did. If I remember it was a common multipurpose relay used in a lot of GM vehicles. It had ignition sense to isolate the second battery when the engine was off.

Click to expand...

Smart, I didn’t think to look through the upfitter guide. I skimmed through the guide and the only mention of anything isolation is this little bit when mentioning l electrical equipment:

“Isolated, Auxiliary 730 CCA, 70 amp-hour battery without battery run-down
protection for customer installed equipment. “

So then this means an isolation relay is in place, right? Or ..

Doubeleive said:

commonly they are just connected in parallel

Click to expand...

I guess that means wiring a sound system to the aux battery would be pointless, lol.

justchecking said:

Mine is set up so the primary passenger side battery is used for every thing. The second drivers side battery is only used for starting if the primary is dead. There is an isolation module that connects both only when engine is running for charging. If I need to start from the secondary battery I toggle a switch. Look up Hellroaring battery systems.

Click to expand...

Nice

Question. The isolator switch allows the battery to accept charge while the engine is running, but produces no output unless the switch is flipped, yes? Would the aux then act as the primary battery until you could replace the main or would you still have to switch it back over to the main for normal driving

Would you care to elaborate any further on your set up

PPV_2018 said:

Smart, I didn’t think to look through the upfitter guide. I skimmed through the guide and the only mention of anything isolation is this little bit when mentioning l electrical equipment:

“Isolated, Auxiliary 730 CCA, 70 amp-hour battery without battery run-down
protection for customer installed equipment. “

So then this means an isolation relay is in place, right? Or ..

I guess that means wiring a sound system to the aux battery would be pointless, lol.


Nice

Question. The isolator switch allows the battery to accept charge while the engine is running, but produces no output unless the switch is flipped, yes? Would the aux then act as the primary battery until you could replace the main or would you still have to switch it back over to the main for normal driving

Would you care to elaborate any further on your set up

Click to expand...

unless the primary battery is flat out bad (will not hold any charge at all) then you would only use the auxiliary battery to start it
the general rule of thumb is to use 2 new battery's of the exact same size type and age, so the chances of one just going bad out of the blue are slim
I just replaced both of mine yesterday at almost 5 years old

PPV_2018 said:

Smart, I didn’t think to look through the upfitter guide. I skimmed through the guide and the only mention of anything isolation is this little bit when mentioning l electrical equipment:

“Isolated, Auxiliary 730 CCA, 70 amp-hour battery without battery run-down
protection for customer installed equipment. “

So then this means an isolation relay is in place, right? Or ..

I guess that means wiring a sound system to the aux battery would be pointless, lol.


Nice

Question. The isolator switch allows the battery to accept charge while the engine is running, but produces no output unless the switch is flipped, yes? Would the aux then act as the primary battery until you could replace the main or would you still have to switch it back over to the main for normal driving

Would you care to elaborate any further on your set up

Click to expand...

Yes the aux would act as the main but if the main is really really bad it could pull down the aux over time. When my main went bad this summer on the 2011 I just flipped the switch to start for three days while AutoZone decided the old main was bad. It was under warranty and they kept testing it before that finally replaced it for free.
The switch could be placed in the cab but I just leave mine under the hood.

justchecking said:

Yes the aux would act as the main but if the main is really really bad it could pull down the aux over time. When my main went bad this summer on the 2011 I just flipped the switch to start for three days while AutoZone decided the old main was bad. It was under warranty and they kept testing it before that finally replaced it for free.
The switch could be placed in the cab but I just leave mine under the hood.

Click to expand...

Nice

This is definitely on my to-do list

I’ve set my Yukon XL up with dual batteries and Redarc isolator and been happy for years. They work as a single battery TBH. The main battery runs things as normal, pivots to spare when volts drop to certain level. The Alternator will charge both batteries back up starting with main, then hits the volts needed and switches to aux. Make sure your alternator is the larger size to put out the needed amps. Agree it’s necessary to start out with two NEW batteries of the EXACT same type/specs. And, form experience, stay away from AGM as the voltage is “too” regulated and too low for the isolators set to expect higher low voltage cutout ranges. If I were to start over, I’d upgrade to a Redarc BCDC and inside cabin outlets. I also installed the emergency jumper wire and saved me a few times. I use my set up mainly to keep “beer and bomb pops” on hand 24*7 for long family roadtrips. It’ll run a fridge/freezer (with real compressor) left in the car in the heat of AZ for 2 days without issue. Never drained the batteries from the fridge; just kids leaving lights on, etc. Then again, I just hold the jumpstart button for a few minutes to join/charge main battery and start it up.