Powering a portable AC/DC Fridge

Steve Hunt · 04-28-2020, 05:22 PM

FYI,
-The van is not built out yet but underway and the fridge has not been purchased yet but looking at the ARB Zero. (If you have experience for or against ARB Zero, I'm all ears)
-Electrical will include connection from shore power/generator
-House batteries and inverter.
-On the body of the fridge is both a connection for AC and separate one for DC
-Where the fridge will sit when used in the van i plan to have both a ac and dc outlet

So the question is when the fridge is in use in the van do you plug in both AC and DC cords from the fridge to their respective wall outlet in the van. Then if the van is powered via shore power/generator the AC outlet is hot and powers the fridge. If shore power goes away or if i simply leave the camp site then the fridge is already plugged into the DC outlet and house batteries power it direct rather than powering it on AC through the inverter while driving. Is this correct approach/thinking. I called ARB and asked and did not get the warm fuzzy from "support"

Steve

Newbie...bought a 2008 E350 long body V10 cargo 17,000 miles...freaking out at the out flow rate of $$

Grampswrx · 04-28-2020, 05:50 PM

So are you running the systems separately? In my vans there is only one plug for the fridge and either the shore power is charging the batteries or not and the fridge always runs off the batteries. Does that make sense? So I always have it plugged in to AC power.

Steve Hunt · 04-28-2020, 07:40 PM

Quote:

Originally Posted by Grampswrx

So are you running the systems separately? In my vans there is only one plug for the fridge and either the shore power is charging the batteries or not and the fridge always runs off the batteries. Does that make sense? So I always have it plugged in to AC power.

The "systems" are in design right now...in this conversation but yes i was thinking there would be a DC bus with circuits off the house batteries and a AC bus that gets its power from shore power/generator or from the DC to AC inverter.

Is your fridge a AC/DC portable fridge? or just a AC fridge?

I don't know how these devices work is part of my problem or if there is a normal setup and why?....so what you're saying is that when you are on shore power that AC runs to a DC charger to charge your batteries, the batteries send DC to your inverter, the inverter changes it to AC and powers your outlet and fridge. Seems like a LONG way around. I would think that when on shore power that the charger-batteries-inverter would all be bypassed and the AC shore power would power the AC outlet/fridge directly. But I don't know, I'm gathering info trying to figure it out.

Hard to believe ARB support couldn't answer me convincingly but what senario do they have in mind for running the fridge on DC by plugging into the DC input on the fridge body? Is it only for a guy that has no DC to AC inverter and no AC shore power? or does the fridge have its own inverter built -in? It must, the fridge compressor can't really accept both AC and DC...there aren't 2 compressors in there? nah

Steve

rumrunner73 · 04-29-2020, 01:14 AM

How it was explained to me . 12 volt is the power you want , keeping the unit plugged to 120 volt will require you to turn on inverter to power refer . 12 volt house batteries will run it just fine and will charge and feed power continually regardless if your driving or parked .

Twoxentrix · 04-29-2020, 04:34 PM

Hook it up as DC. If and when you plug into shore power you'll be charging your house battery (which continues to sustain your fridge at the same time)

Herbie · 04-30-2020, 11:00 AM

Most RV systems with AC tend to separate "Inverter AC" from "Shore-Power" (or Shore-and-Genset AC ).

You can certainly plug the AC input of your fridge into the Shore/GenSet AC if you like, but there's a major loss of efficiency to fire up your inverter, so skip that.

I went simpler: I have a DC-only fridge, plugged into the house-battery. My "Shore Power" input drives the battery charger, so when I'm docked (at home, generally) the AC powers the DC charger which keeps the battery topped, which powers the fridge.

velo47 · 04-30-2020, 11:46 AM

Quote:

Originally Posted by Herbie

I have a DC-only fridge, plugged into the house-battery. My "Shore Power" input drives the battery charger, so when I'm docked (at home, generally) the AC powers the DC charger which keeps the battery topped, which powers the fridge.

This is what we did in our Sprinter as well. We saw no need for AC power for the fridge. But the main reason we did it was the DC fridge was less expensive than the AC/DC!

Steve Hunt · 04-30-2020, 03:38 PM

Quote:

Originally Posted by velo47

This is what we did in our Sprinter as well. We saw no need for AC power for the fridge. But the main reason we did it was the DC fridge was less expensive than the AC/DC!

I didn't realize a DC only fridge was cheaper....good to know.

Quote:

Originally Posted by Herbie

Most RV systems with AC tend to separate "Inverter AC" from "Shore-Power" (or Shore-and-Genset AC ).

You can certainly plug the AC input of your fridge into the Shore/GenSet AC if you like, but there's a major loss of efficiency to fire up your inverter, so skip that.

I went simpler: I have a DC-only fridge, plugged into the house-battery. My "Shore Power" input drives the battery charger, so when I'm docked (at home, generally) the AC powers the DC charger which keeps the battery topped, which powers the fridge.

For DC only fridge then i agree this is the ticket.

I'm still thinking a fridge that can take both AC and DC for flexibility might be the thing for me. Maybe be able to use the fridge at home for emergency or extra capacity. I assumed the inverter was bypassed completely if shore power was present and my van AC wall outlets were hot directly from shore power so no loss of efficiency...I'll need to dig into that, Thanks.

Russ Gutshall · 04-30-2020, 06:58 PM

Maybe get an ac to dc converter for home/emergency use - not sure on the cost ?? Amazon ?

Herbie · 05-04-2020, 10:39 AM

Quote:

Originally Posted by Russ Gutshall

Maybe get an ac to dc converter for home/emergency use - not sure on the cost ?? Amazon ?

Like I said, my battery charger serves this function perfectly, since it easily provides more current than the fridge can ever consume, it's basically acting as an AC-DC converter for the fridge (while also silently maintaining the house battery in the background.

I could maybe get by without it now that I have a East-Penn/Deka house battery (since the solar can keep things happy), but when I had an Odyssey AGM, my AC powered charger was the only thing that had enough juice to adequately charge the battery since the Odyssey's chemistry prefers a really high charge current. (45+ Amps!)

And yes, I use mine as a backup fridge all the time. We're in "shelter at home" mode here in SoCal and my van's fridge is holding the overflow bulky items that I don't need immediate access to in the house. (2nd container of milk, eggs, extra beer, etc.)