Dual Battery Setups! Let's see them! Multiple Batteries Thread!

Hey ya'll, hope everyone is taking care of themselves and each other with this crazy Covid-19 crisis. I had a question for those who are running a fridge in their camping set up. Are any of you using a separate battery to run the fridge or using the existing truck battery? If you are using a separate battery, can someone point me to a thread that explains the DIY process or explain how to set up a secondary battery to use for the fridge so I don't suck my existing battery dry when I'm out camping? Thanks, I hope the question wasn't too confusing. I'm not mechanically smart like a lot of folks on the forum or can geek out in details, fyi. Stay safe!

 

I may be wrong but that's this thread. Go to page 1

 

Separate battery, a DC-DC charger.

This is the thread - happy reading!

 

True. I have been looking at them because a 24V truck can then charge a 12V house battery for overlander junk. 24V JDM truck sometimes sucks.

 

Is there any downside to keeping the starter battery as a flooded cell battery and having an AGM as the aux battery and using the redarc controller to charge it?

 

As long as the 2 batteries are isolated from each other, you will not have a problem.

CTEK also makes DC-DC chargers - compare to Redarc.

 

This^^^. I'm installing a CTEK D250SA. My starting battery is an Odyssey 34R-PC1500 and the service battery is an Odyssey 34M-PC1500 marine battery with dual terminals. Finding a spot to put it in my '06 Access Cab was a challenge. I used an Artec battery box and moved the air intake from the fender and used a Spectre air tube and ran it to the front. The mounting of the CTEK piece will be on the driver's side and uses some existing bolt holes in the fender. Next step is wiring and we'll see how it goes.

 

That is actually pretty genius...I might have to look into something like that if I go with a dual battery

 

Saw this thread popping up again on the home page and thought I'd go ahead and share this. I've been running this setup for about a year and a half. This plywood and lumber battery box is mounted in the bed of my truck under my AT Habitat. My fridge sits on top of it (2nd pic). I have 2 Blue Top Optimas, group 27. They are connected to my starting battery through a Bluesea ML-ACR. I never actually switch the ML-ACR to connect the batteries unless it's to jump my truck (recently replaced original battery with a yellow top optima, so hopefully no more jumping). Charging the batteries before I leave home with the Noco Gen2 charger and then using my 100 watt solar panel to keep it charged while camping hasn't failed me yet. Max trip was around 5 days so far. Main drain is the 75 liter Dometic Fridge.

My original plan was a second battery under the hood, but decided two extra batteries was better than one, and I mounted my ARB compressor under the hood instead.

 

Hmm, I looked hard into the redarc vs ML-ACR and the ACR seems like the better way to go.

My plan is to leave both batteries tied together most of the time. If I'm going camping or running a constant electrical load when the truck is off, I'll use the ACR switch and disconnect the two batts so only the secondary battery is used. Also, I'm throwing 200 watts of solar on the roof, in which case I'd just leave both batts connected during the day so they will both stay topped off.

Do you see any holes in this plan?

Side note: I hate these 'smart' alternators, even if they are more efficient.

 

Do your batteries match? Curious if there would be any issue with the solar attached to one of the batteries, and then to the other battery via the ML-ACR. If it's connected the whole time would one battery be sucking juice from the other battery, not just from the solar panel? And could it be an issue?

 

I've got 2 AGM batteries, although they are different sizes. I'm not quite sure if there will be issues with this setup or not with one battery draining from the other. I kind of do want the redarc charger, but I wish it had a bluetooth connection for the solar mptt controller on it. Does anyone know of a way to connect something to the redarc to be able to see data on the solar input and output?

 

I didn't plan it this way, but after having it installed for months I realized with the ML-ACR attached to a manual battery switch I could have my fuse block/solar controller hooked up in between. So if I disconnect the battery at the switch, and connect the ML-ACR I can run my stuff off the Truck battery, and charge it via solar. Then if I disconnect the ML-ACR and flip on the Battery switch I am running completely off the House Battery, and charging just that battery. I originally installed the switch because I had two house batteries i wanted to separate (4 position switch: bat 1, bat 2, bat 1+2, off). A standard battery disconnect would work with just the single house battery.

Did that make any sense? lol.

 

Hmm, It kinda does, but my brain is feeling a bit fried at the moment as I'm just now signing off work. I need to step away from the monitors for a bit and then re-read this because there might be something to your setup that I may use in mine.

I guess some more points to add on what I'm going for.

1. I would like my solar to be able to charge both the starter and the aux battery, but charging the aux battery is obviously the number 1 priority.
2. Solar aside, the charging situation is a problem no matter what. Our alts don't charge agm batteries well, so I may have to do something different down the road for that if the solar isn't enough. That goes for both the starter and aux battery. (redarc charger or aftermarket alt, etc..)
3. I still like the idea of being able to tie both batteries together when I want to. That's another problem I have with the redarc.

It kind of seems like I need both the Blue Sea MLC-ACR AND the redarc dc to dc charger. It's an expensive setup, and might be tricky to figure out all the wiring for it but it might be the best option. Technically I could get away with the redarc charger and a cheaper relay to connect and disconnect the 2 batteries, but I've already ordered the ACR..

 

I run a CTEK D250SA and dual Odyssey 34R-PC1500s, both in Artec boxes. My second is mounted in the bed, under my platform.

 

The smart alternator is the flaw in your plan.

The alternator will not keep 2 batteries (tied together) charged. Once 1 battery reaches proper charge, the alternator will stop charging.

 

On the second battery, how do you use it and what have you done to be able to use it? I have some ideas about switching some current loads over to the second battery but looking for ideas.

 

The battery is charged by the D250SA, when the truck is running.

Attached to the battery are (via a fuse block) - Engle fridge, Viair compressor, interior shell LED light, aux power for my teardrop (used when camped). The fridge runs almost all the time (fresh sandwiches for lunch at work! ) When camping, the teardrop has all LED lights, but aren't on that much (we like to camp in the dark.)

Since the 2nd battery cannot jump the truck with the flip of a switch, I have other options. First, I carry a jump box - small, and very effective. Second, I can run jumper cables from the 2nd battery to the first. Third, since I run the same battery in both locations, if the starting battery was to physically fail, I can pull the 2nd battery out and put it under the hood replacing the starting battery. Extreme? Yes. But, twice in 30 years I have had a battery fail.

To summarize, the truck's electrical system is basically unchanged - the second battery is part of an additional and stand-alone electrical system.

Does that answer your question?

You can find some pictures of this in my build thread (near the end.)

Oh, don't forget - AGM batteries prefer a higher charge voltage than flooded cell batteries.

 

This is what I'm curious about. I have the whole thing figured out in my head. I'm looking for the actual execution so it doesn't look like I'm an idiot. I'll go check out your build.

I've got just about the same setup in mind. I have the

$100 NOCO GB40 1000A UltraSafe Car Battery Jump Starter, 12V Jump Starter Battery Pack, Battery Booster, Jump Box, Portable Charger and Jumper Cables for 6.0L Gasoline and 3.0L Diesel Engines

NOCO GB40 jump battery, the jumper cables, the ability to move the batteries if needed. This will be for refer, lights, compressor, etc. I just wanted to take all of the accessory responsibility away from the starting battery.

 

I watched that video linked earlier on the redarc charger. I see it keeps your secondary battery charged, and at a higher voltage than the alt can put out which is great. Does it do the same for the starter battery?

Edit: Im going to assume it doesn't and I'd need to top off the starter battery at least once a month