Single battery setup vs Dual battery setup

[Mr_Miyagisan]

So im seeing on this forum that there is a lot of people who just want to jump straight to a dual battery setup. And the more and more I read up on them I am finding MOST probably don't even need it. For example im going to be running a Fridge in my XJ and im leaning more towards a large single battery setup (group 31) marine battery instead of a dual batteries
1. For simplified wiring (think there is a saying simple is better in overlanding)
2. Because without relocating the airbox you cant put another battery in an xj engine bay, forcing you to place it in the rear leading to less cargo space.
Is there anything wrong in my thinking of this? With a jump pack as a safety net I don't see why this wouldn't be able to be just as good of a setup for lower cost and a more simplified vehicle in general

Thanks for reading!

 

[jeegro]

Before I had my dual battery setup, I had a similar thought process. It's not until I installed it do I realize how much peace of mind it affords. You can leave the fridge running and never worry about it affecting your starter. I moved all the stock car electronics (fuse box, stereo, etc) to the house battery too, for even greater peace of mind.

I was still worrying about damaging the house battery by over discharging it. Then I added a battery monitor and I finally feel like I have a good solution.

Can you do without it? Sure. Especially with a group 31. For me, I want to build as much self reliance into my vehicle as I can, to a reasonable degree.

Edit: if you have a group 31, I highly recommend a solar setup and or hooking up a battery charger once a week. Test your alternator output, there's a good chance it can't keep that battery properly topped up

 

[Martinjmpr]

Before I had my dual battery setup, I had a similar thought process. It's not until I installed it do I realize how much peace of mind it affords. You can leave the fridge running and never worry about it affecting your starter.

.
Yep, this right here for me. Of course, I have the advantage of having a vehicle that came from the factory with a space for a 2nd battery (full size GM) so IMO the most difficult part of a dual battery system - where to put the 2nd battery - was already taken care of in my case.
.
Just knowing that the fridge is not connected to the starter battery gives me the peace-of-mind of knowing that I will always be able to start the truck, no matter how warm it gets or how hard the fridge has to work.

 

[SnoViking]

I went through a similar thought process with my recent build. I ended up sticking with a single battery (group 24F AGM). I run a fridge and a few LED light strings but that's about it. I do carry a portable jump pack though just in case I get lazy. We don't tend to park very long (maybe 36 hour total) so we're usually driving and recharging the battery. I do "supplement" with a 100w solar panel and monitor the volts.

 

[BigSwede]

I was *this* close to installing a dual battery system, was getting ready to relocate the airbox to make room for the house battery, etc. etc....then changed my mind and installed a single group 31 and carry a LiFePO4 jump starter as backup.

This way I actually get more usable power for the house, having 50 ah available before 50% discharge, versus 25-30 ah for a group 34 house battery. And it is indeed much simpler. This setup has worked perfectly for 4 years now. Never have had to use the jump starter.

 

[e60ral]

I also just use a 31m battery and have a lithium jump pack backup.

I run a Dometic 40qt daily, I have the automatic voltage shutoff set at 11.8V (about 70% charged for my battery) but have not yet hit the shutoff with just daily commute to and from work and even sitting for a weekend. When temps start getting around 100 degrees I would guess that weekends might draw it down enough to hit the automatic shutoff but I have a NOCO on-board charger I can use at home and will get 100-200watts of solar for camping. Generally my camping has me driving every day though, so I doubt the solar will ever be necessarily needed. I could also just drop the automatic shutoff to 11.4V which is about 25-30% state of charge, I wouldn't want to constantly cycle my battery that low but a dual purpose battery could handle that if it needed to on occasion.


You might as well start with just one battery, you can always add another later if you find its not enough, that's my plan

 

[Bear in NM]

The question is really no different than any piece of gear we carry when in the out and about. How much backup is needed for everything? Spare tires, water, flashlights you name it. The answer will be completely different for every person.

Personally, when camping, I am there to enjoy what ever the draw was for the location. I do not want to "worry" about things. But to be completely honest, my newer solar system does not worry me per se, but I do derive enjoyment out of having it, and piddling around with it. Some folks find the remote enjoyment of a good book sitting under a tree. I derive the same kind of enjoyment with my solar system.

I am remote a lot by myself. I do have a jump pack in my truck, but I also actually enjoyed the process of installing my second battery, and having ready if I may need it. But "need" is a tricky concept, if one is honest with oneself.

Craig

 

[e60ral]

Yeah it all just comes down to what you need, how you are going to use it

The battery itself or being able to start in the morning isn't the concern; its pretty easy to voltage protect the battery, your fridge probably has an automatic shutoff so the risk isn't really the car not starting in the morning (and you can further mitigate this with a jump pack) its more an issue of the fridge shutting off.

Because of that I think the questions you need to ask are:
1) What is my use? Will I be driving this vehicle daily or do I often camp for a few days without using my vehicle much?
If you are driving every day and your load is just the fridge and maybe charging phones or something, a single 31m battery is probably sufficient, especially if you add some solar charging. If you are camping for a few days and not running your vehicle much you might want more capacity (and more solar).

2) How bad will it be if my fridge shuts off and I lose some of my food? If your camping trips are in campgrounds near towns, or maybe you use a lot of dry food and your fridge is mostly beer or something than this isn't a huge concern. If your trip is very remote and losing food would cause you to majorly interrupt your trip or cause major headaches then some extra capacity is probably worth it even if you may never end up needing it.

and related to both of those:
3) what is my climate? running a fridge you will obviously want more capacity if the ambient temps are 100 degrees vs 50 degrees.

 

[lathamb]

I have dual batteries on my 4Runner, made based on the thread in this forum on how to make a cheap isolated dual battery system. I have a DHP GP31 as the main and a Deka AGM GP 34 as the secondary. I probably didn't need it, but I like tinkering, it was cheap, and I already had a spot to put the second battery. That being said, I'm glad its there when I'm out by myself.

 

[Scoutn79]

Even if you have a large battery at some point that battery is going to get weak and you may not notice. At that point the fridge might just kill the battery in a day and then what? I had that exact scenario happen once. Dual batteries are just are piece of mind if you travel alone. I also had a battery bust internally once at the end of a rough 4wd trail. Just like the old saying says don't keep all your eggs in one basket...

Darrell

 

[pluton]

I elected to get a Nat. Luna portable pack, since I knew I'd be changing vehicles sometime later that year. Thick batt cables permanently installed from starting batt, down the frame rails, and into the cabin under the driver's seat. Same group 34 batt in pack as under hood. Pack sits next to the fridge in rear cargo area of '97 4Runner when camping. I have the option of using the Nat. Luna system to join both batts, or, in case the Nat.Luna goes crazy or fails, to skip the Nat. Luna entirely and hard wire the 2 batts together. The two G34 batts probably have a bit more power reserve than a single G31, and without the potential charging voltage issues of a G31.
I like keeping the starting batt separate and 'always there', plus repeated deep discharges speed up the demise of any batt...even fancy Odyssey AGMs.

 

[BigSwede]

The two G34 batts probably have a bit more power reserve than a single G31,

Yes, but you don't use them together, that's the whole point of a dual battery system.

 

[Bane Harper]

I have the similar confusion, but then go with dual battery. You don’t have to worry about your starter, a solar panel as a supplement would be handy if you like

 

[ducktapeguy]

I'm going through the same dilemma right now. My electrical needs are pretty simple right now (freezer and some LED lights) but still want to do a dual battery setup for peace of mind. A larger battery will give you more capacity, but doesn't give you redundancy. I have a couple of those lithium jump packs, along with a few standard SLA jump packs, but don't consider them a true backup because while they're able to jump start a depleted battery, in my experience they won't start a car by themselves (fully dead or damaged battery). I'm not sure if a larger capacity battery would help or hurt in those situations where the starting battery is discharged.

What I tried last weekend was a poor mans version of the NL power pack. I charged my SLA jump starter while driving, and while parked, I ran my freezer off it. All I really need is enough power to keep the fridge running overnight without killing my main battery. Didn't work too well, but it could be my jump pack is old too.

 

[e60ral]

The NOCO GB40 and Antigravity XP-1 have been shown to start an engine without a battery

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