Single battery setup vs Dual battery setup

[trifreemc]

Ok, just when I think I have this figured out, I read something else and probably just end up confusing myself. I have a 2005 Suburban and it has a spot for a 2nd battery so that's an easy option if going that route. Been reading up on the isolator kits and what I thought I understood is when not running and the starter battery reached the limit set by the isolator everything would switch over and draw from the 2nd battery. In further reading however it seems I might be mistaken and all of the electrical will still draw from the starter battery; stereo, interior lights, all of the 12v plugs (there are 3 or 4 of them) unless I redo the wiring on these to pull directly from the 2nd battery.

My goal is to be able to run an ARB + an inverter for fans, charging, misc...

Help me unconfuse myself...

 

[Martinjmpr]

Ok, just when I think I have this figured out, I read something else and probably just end up confusing myself. I have a 2005 Suburban and it has a spot for a 2nd battery so that's an easy option if going that route. Been reading up on the isolator kits and what I thought I understood is when not running and the starter battery reached the limit set by the isolator everything would switch over and draw from the 2nd battery. In further reading however it seems I might be mistaken and all of the electrical will still draw from the starter battery; stereo, interior lights, all of the 12v plugs (there are 3 or 4 of them) unless I redo the wiring on these to pull directly from the 2nd battery.

My goal is to be able to run an ARB + an inverter for fans, charging, misc...

Help me unconfuse myself...

Sounds like you are contemplating one of those "smart" isolators that senses battery voltage? If so I'll have to defer to those that use such a system.

Mine is a basic "dumb" isolator, a simple on/off switch. When the ignition is on the circuit is closed and the two batteries are connected. When the ignition is off the circuit is open and the "house" battery is not connected to the starter battery.

I have a fuse block on my "house" battery, and from that fuse block (fused with a 15a blade fuse) I run a power wire along the firewall and into the passenger compartment, then under the door sill plates to the plastic interior panels behind the 2nd row seat. In there I put in a 2 x 12v power outlet, one with a dual USB and one just a regular power outlet, and that's where I plug in the fridge. This has been my setup for the last 20 months or so, and the only time I've had "issues" is when I was 'wheeling a little too hard and the ground wire for the 2nd power outlet became detached from the outlet.

My 2nd battery even saved my bacon once, when the alternator failed. The 2nd battery provided enough extra juice to get me home (although, to be fair, if I hadn't had it, it would have only taken me a half hour or so to change the alternator by the side of the road, and one of the many nice things about GM trucks is that if you need a part, the local parts store is likely to have it in stock.)

IMO the most difficult part of any extra battery installation is "where to put the 2nd battery?" Modern vehicles seem to have very crowded engine bays which makes placing the 2nd battery a very tricky proposition, requiring you to do things like relocate air boxes, move windshield washer tanks, etc.

On the GMT-800 trucks, by contrast, , it's a cinch because the "spot" for the 2nd battery is already there, so that makes the installation much, much easier.

 

[trifreemc]

smart isolator or dumb isn't really my hangup... i'd like to leverage the always "hot" 12v plugs throughout the Suburban without draining the starter battery and was originally thinking installing a deep cycle in the empty battery tray in the suburban with an isolator would let me do just this when the vehicle is off. I've seen comments though stating I'd need to rewire those 12v outlets to the auxiliary battery after installing it. This is where I'm slightly confused I think.

 

[Martinjmpr]

smart isolator or dumb isn't really my hangup... i'd like to leverage the always "hot" 12v plugs throughout the Suburban without draining the starter battery and was originally thinking installing a deep cycle in the empty battery tray in the suburban with an isolator would let me do just this when the vehicle is off. I've seen comments though stating I'd need to rewire those 12v outlets to the auxiliary battery after installing it. This is where I'm slightly confused I think.

Yes, that's correct they are currently wired to the main battery so you would have to actually physically run new wires from the 12v outlet to the house battery. Either that or you would have to run a wire from the house battery to the interior of the truck to a new fuse block and attach the power wires for the 12v outlets to that fuse block.

For my purposes, at least, it was easier to just put in a new dedicated 12v outlet wired to the house battery.

 

[trifreemc]

Yes, that's correct they are currently wired to the main battery so you would have to actually physically run new wires from the 12v outlet to the house battery. Either that or you would have to run a wire from the house battery to the interior of the truck to a new fuse block and attach the power wires for the 12v outlets to that fuse block.

For my purposes, at least, it was easier to just put in a new dedicated 12v outlet wired to the house battery.

Yeah... would love to figure out a way to simply swap the existing 12v plugs over to an auxiliary but it might just be easier to fish new ones to the back from a 2nd battery.

 

[feltyellow]

Quick question for those with single battery setups -- I assume stock starting batteries won't work at all, any recommendations on what to replace it with? Would costco "dual" basic lead acids be enough or is it worth going for a "dual" agm?

 

[luthj]

Odyssey makes some great batteries that can do dual purpose. Lifelines are spendy, but will do double duty without issue. Some marine starting batteries have thicker plates, and will last longer in a deeper cycle usage than regular starters.

AGM batteries tend to have higher CCA while still having good plate stability, so they can tolerate modestly deep discharges without crapping the bed like a regular flooded starter battery.

 

[Ducky's Dad]

Lifelines are spendy, but will do double duty without issue.

Most of the GM trucks that I have looked at use Grp 34 or 34/78 batteries and when I looked at Lifelines over the last couple of months they did not have anything in a Grp 34 form factor. The problem is the height of their batteries, so you might be able to find a way to fit one, but there was nothing for my installation. I went with V-Max for my Grp 34 house batteries because they actually make a BCI Grp 34 true deep cycle AGM, but it is in their medical battery line so it's easy to overlook. Should fit the second battery tray in the GMC with no mods.

Some dumb isolators (like mine from Painless Performance) will allow you to combine batteries when the truck is off, so that accessories will draw from both battery banks while parked. That eliminates need to wire additional outlets, but means you could drain both batteries if you are not paying attention. Another alternative might be the dumb isolator with a separate kill switch on the starting battery so that the constant hot outlets only draw from the second battery when parked.

 

[Wallygator]

I like the idea of having a portable second battery such as this....

https://newportvessels.com/smart-battery-box/

Sort of a portable house battery that I can take from the 4runner and use it other places such as in the RTT on the M416 trailer. Is this a dumb idea? Meaning would it just be better to have a dedicated second battery in the engine bay and just run an ext cord to the trailer?

My thought process, or lack there of, is that if I ever do get a fridge the house battery will right there by the fridge and everything can be pulled out of the 4 when not needed. When it's in the 4 I would want the portable house battery to be charging while driving and to have solar capability when camping.

Any thoughts on if this is a smart solution and if so how would something like this be accomplished? Andersen connector? What type and where to mount the charger? I have never had a dual batt system and I am a complete beginner as to the logistics of it all. Thanks.

 

[Martinjmpr]

I like the idea of having a portable second battery such as this....

https://newportvessels.com/smart-battery-box/

Sort of a portable house battery that I can take from the 4runner and use it other places such as in the RTT on the M416 trailer. Is this a dumb idea? Meaning would it just be better to have a dedicated second battery in the engine bay and just run an ext cord to the trailer?

My thought process, or lack there of, is that if I ever do get a fridge the house battery will right there by the fridge and everything can be pulled out of the 4 when not needed. When it's in the 4 I would want the portable house battery to be charging while driving and to have solar capability when camping.

Any thoughts on if this is a smart solution and if so how would something like this be accomplished? Andersen connector? What type and where to mount the charger? I have never had a dual batt system and I am a complete beginner as to the logistics of it all. Thanks.

How would you charge it?

 

[Wallygator]

How would you charge it?

This is what I am trying to figure out but not many are offering input about it.....So I was thinking about a dc to dc charger close to the aux. battery wired from the vehicle battery. Then possibly add a solar system later on to supplement. When not on a trip I can easily take the battery out of the vehicle and put it on the battery tender.

 

[Borrego60]

I have a Renogy 100watt 1/4 inch in height, never would know it was there on top of my camper shell, running to a controller of course, This goes to my #2 Deka grp31 battery in the bed of the truck,it runs my fridge and other electronics. That is connected to a Blue Seas automatic voltage sensing relay Term #2 and Term# to my starting battery #1 Deka Grp 31.I did have a Painless solenoid, remove that and went with the Blue Seas smart relay. Solar charges all day long and the Blue Seas switches back and forth as needed. System has worked great and never looked back. Even let the truck sit for 3 weeks with radios and fridge running. Got in and started right up!

 

[Borrego60]

Dunno where you read that, but it's a load of BS.

To fully charge a lead-acid battery, you have to get it up above 14 volts and hold it there for as long as it takes it to absorb all it can.

Since every car builder knows that, every component of every car is designed to handle it.

You can do the job with an alternator, a shore powered charger, a solar system - doesn't matter, they all do the same thing; raise the voltage and hold it there.




Depends on the isolator.

If it's a smart isolator, a.k.a. automatic connection relay (ACR) such as sold by Bluesea, Samlex, National Luna and others, then it detects elevated voltage on either side and automatically connects the batteries together so they both charge - together - from a single source, whether that source be an alternator feeding to the engine battery or a solar system feeding to the aux battery.

Blue Seas are great I love mine.

 

[Wallygator]

I have a Renogy 100watt 1/4 inch in height, never would know it was there on top of my camper shell, running to a controller of course, This goes to my #2 Deka grp31 battery in the bed of the truck,it runs my fridge and other electronics. That is connected to a Blue Seas automatic voltage sensing relay Term #2 and Term# to my starting battery #1 Deka Grp 31.I did have a Painless solenoid, remove that and went with the Blue Seas smart relay. Solar charges all day long and the Blue Seas switches back and forth as needed. System has worked great and never looked back. Even let the truck sit for 3 weeks with radios and fridge running. Got in and started right up!

Thanks! This is the kind of real world advice I am looking for. Is the blue sea mounted under the hood or in the bed? I'm assuming the solar controller is in the bed with #2. Also, what size wiring did you use for the longer runs?

 

[Borrego60]

Blue Seas is mounted under the hood.Solar controller is mounted in bed by #2battery, I ran 1/0 cable for jump starting from rear battery. All I did was removed the painless and put in the ACR from Blue seas. Controller wire was 10G from panel to controller and 10G again to battery, Everything is fused too from panel and controller to battery. I"ll post up some pictures.