Single battery setup vs Dual battery setup

[rruff]

draw about 1 ah...

1A is a good ballpark average. In this test they varied between .73 and 1.58A: http://www.arbusa.com/uploads/Newsletter/ARBmegaFridgeComparo.pdf

So in a typical 24hr day your battery would draw down ~75% of capacity. And if you have decent sun a 100W panel will more than compensate.

 

[con kso]

Single battery power source works. Don't worry about all the conjecture if it might work and so on... I'm here to tell you it does.

I've been running this for three years now powering the largest ARB refrigerator on three week long trips to Southern Baja.

During the day I open up my Zamp solar panel I think it's 120watts and run it until the controller screen says the battery is full. Just two weekends ago I had the refridgerator on -10C or something nuts like that up in the high desert at Willow Springs Raceway. My Tecates were ice cold and my car truck started up no problem.

I think a double battery system with matched 31 series Odysseys is totally killer but it's more $$$ than I want to spend and more tinkering than I'm willing to do. If I had the time, money and knowledge to set one up like that, I'd do it- just because I like to look at my truck and think about how "set up" it is... man toys.

I do carry a jump pack to start the truck but I've found that what's really happening is that I'm carrying that jump pack to start all my friends who drive ****ty cars with unreliable batteries.

 

[Theo85]

I only have the 100ah starting battery and my fridge never draws it down beyond about 70% charged with daily driving

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And you are not using a solar panel, correct?

 

[Theo85]

I don't think so. Refrigerators take a lot of juice. Do you know how much? Very important.

Figure your battery is only good for half it's capacity (~500W-hr), and an average sunny day you will get you ~500W-hrs as well from the panel (if facing the sun). So you can barely draw 20W for 24hrs on a cloudy day before the battery is used up. If it's sunny then you've about broken even.

Looks like worst case is 4.5a will compressor is working, and ~1.5 when not. I have yet to confirm these numbers myself as they're just from other posts of the whynter 45qt fridge.

 

[Martinjmpr]

I'm debating this as well. I'm currently putting together my fridge/solar setup.
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Let me know what you guys think:
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I am only powering my fridge via the solar setup. I have 100watt solar panel, 45qt fridge, charge controller and the plan is to place a deep cycle battery (90-100ah) in the rear of my 4runner.
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Thats going to be isolated from everything else. Is it overkill?

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IMO there's no such thing as "overkill" when it comes to batteries. It's kind of like the old aviator saying: "The only time you have 'too much fuel' is when you're on fire."
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Or to put it in Facebook-speak: "This battery has too much capacity" - said nobody, ever. :sombrero:

 

[e60ral]

And you are not using a solar panel, correct?

No, but I plan on eventually getting a 100W for the times when I'm camped and not driving daily. I also have a NOCO on board charger for when I'm parked at the house for extended time and also for occasional maintenance charging to make sure my battery is properly charged (my vehicle charges <14V)

And you are not using a solar panel, correct?

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[rruff]

Looks like worst case is 4.5a will compressor is working, and ~1.5 when not. I have yet to confirm these numbers myself as they're just from other posts of the whynter 45qt fridge.

Look at the test I linked on the previous page. I doubt your Whynter uses more than 1.5A average.

 

[e60ral]

Looks like worst case is 4.5a will compressor is working, and ~1.5 when not. I have yet to confirm these numbers myself as they're just from other posts of the whynter 45qt fridge.

it will be using almost no power when the compressor is not on, the ~1.5 amp is the average over time of when it is running and when its not

 

[broncobowsher]

So I bought an ARB (Engle) fridge back in 2008. In 2010 I bought a new Xterra. That fridge pretty much lives in the back. Very rare does it come out. Turn it on as I need it, off when not.
I'll take off on weekends and run it for a couple days. It's plugged into the factory accessory outlet and draws off all factory wiring. The battery was replaced at 6 months with an Oddessey in stock size. It is now 6 years old. I did add a small solar panel. 70W rated but after charge controller it is lucky to make a real 50W. It is mounted flush to the roof, so no optimal sun angle stuff. I prefer to park under trees for shade as well. It's not happy if you try to run in freeze mode all night long, but fridge mode is just fine. I've left it parked and the fridge running for 36 hours and it still starts fine. It does need a solar panel to pull that off as it isn't happy in a hot car without a charge after half a day.

Oh, a dead battery is possible. Wait. Solar will recharge. At worst I may have to wait a few hours and leave mid morning instead of early morning. Solar will still charge even with shade (just not as well). I don't have issues with this. I don't find myself parking in caves and needing to run the fridge. I do have jumper cables and rarely am I that alone. And if I am that alone, I have the time needed for a solar recharge.

I did have a dead battery once. In a parking lot with about 100 friends. Summer with the fridge running hard for the better part of the day. before solar. with a bad factory battery (found out I was part of a bad batch).

So 6 years running this way. Do I have plans to change it? No. I might put a new battery in simply because the old one is getting old. Batteries are not known for a long life in Arizona.

 

[Theo85]

Well I went to cosco and found a 120ah marine/deep cycle battery with a 35 mth warranty for 120$. (Running 100w panel)

I have 10ga wire sitting in front of me and i'm wondering if thats too small to run from the battery to my 30a charge controller? Also what size fuse should i put on the wiring?

 

[Scoutn79]

Well I went to cosco and found a 120ah marine/deep cycle battery with a 35 mth warranty for 120$. (Running 100w panel)

I have 10ga wire sitting in front of me and i'm wondering if thats too small to run from the battery to my 30a charge controller? Also what size fuse should i put on the wiring?

10 Ga is way overkill. Your 100w panel will put out maybe 7 amps tops in full light and 10 ga is rated for about 55 amps for chassis wiring.
For up to 25' of wire 14Ga would do fine. 10Ga would allow you to run up to 65' and still have an exceptable voltage drop.
Of course bigger wire will have less voltage drop but at the cost of flexability and routing/storage of the wiring depending on if you are a fixed or loose panel.

Darrell

 

[Theo85]

Ok glad to hear. Since I bought everything in 10ga i will wire it up as such. Sounds like it will be very effective lol!

Ps is there any danger in turning the fridge off but leaving it connected to the circuit? Do I need a breaker?

 

[e60ral]

There would only be a risk if you had a short that was small enough not to blow your fuse

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[Theo85]

Thanks! I'll post progress pics this week.

 

[JPaul]

I'd wire the circuit between the battery and the charge controller for the max amps the charge controller can put in. That way it does two things:

1: It future proofs the setup in case you end up adding more solar panels or use a higher power input source into the charge controller (You won't have to rewire to handle the increased amperage)

2: You'll improve the efficiency by reducing the resistive loss between the charge controller and the battery. Smaller gauge wire will have higher losses than larger gauge. Though if this is a very short distance then it won't be much at all, but still.

I'd say use the 10 gauge since you have it, it's not hurting anything and could save you headaches in the future.

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