Power an AC fridge from battery

[TimeOutside]

I have an AC-only refrigerator in my 2012 R-Pod 177. Currently, it is powered through a breaker position in my WFCO Ultra III Distribution Center (stock model WF-8955PEC) when I'm connected to shore power. I'd like to have the option to power it from battery via an inverter. What would be the best way of accomplishing this? The only thing I can think of is to install a changeover switch. Something like this: Amazon Link. Is this the best way to go?


Thanks in advance,
Andrew

 

[bikendan]

Please post the fridge make and model number.
The only AC-only fridge in such a small trailer, would be an additional outside dorm-style fridge.
Otherwise a 2012 Rpod 177 would have a 2-way or 3-way fridge.

 

[TimeOutside]

Please post the fridge make and model number.

The fridge is an LIT (Elite) 3.1 Cu.Ft. Compact Refrigerator, model RR001BK. From what I can find online, it looks like it is a replacement purchased from Menard's. I have no idea what was originally in the camper. A fridge powered by AC, DC, or propane would be sweet, but it's not what I have. From what I'm seeing in pictures of other's campers, there was originally a microwave above the fridge. There is just a wooden panel there now.


Thanks,
Andrew

 

[MGD1961]

Choose a large enough inverter “must be true sine wave” that has automatic pass through when it is connected to ac power. Connect it so it supplies all your ac loads except air conditioner. When you plug in to shore power it will automatically switch to shore power.

A DC fridge would be a lot less expensive.

 

[Oaklevel]

What type of battery "bank" do you have? A single lead acid battery will not power the frig more than maybe....... over night?

Replacing a refrigerator with a cheap dorm style is common for those that camp mostly on campground sites with AC power.

 

[TacomaJoe]

If its just to run the refrigerator, then what you need is an inverter with pass through function (automatic transfer). You cut the line powering the refrigerator and insert the inverter.

Inverter location should be near the battery to keep the high current DC wires as short as possible.

 

[Chuck_S]

Nothing has changed from your post on the same subject yesterday. See my Post #8 in this thread. Get the meter and determine your power requirement:

https://www.forestriverforums.com/f...re-out-the-electrical-282638.html#post2993716

-- Chuck

 

[Aussieguy]

How long do you expect to be using inverter power ... before connecting shorepower again?

if it is only so you can travel for a few hours to the next campground
I would just leave fridge OFF and keep door shut as much as possible...

Load up and cool food only while on shorepower (day before trip)
avoid stopping at Walmart to pickup supplies......... at the start of a trip

If you need better fridge time.... get another fridge (12v) you can load/use in the back of the truck...


OTHERWISE ... if you want to camp off grid for a couple of days
battery + inverter to run a fridge will be $$$
$400 battery + $100 - 200 for Inverter + maybe some solar too
it's getting pretty pricey just to power a fridge

I added 740w of solar + 200ah of battery to keep up with my 12v use
cost me $1000 and I could run a small inverter ... IF I wanted to

Your smaller camper won't have the same solar capability on the roof?
you could travel to a campsite and setup a some ground solar?

 

[TimeOutside]

My apologies folks. I'm learning with power related topics that everything is so very interrelated. In trying not to ask every question I have in a single post, I trim it down and make two or three posts. But then I find that some information is needed that I included in another post. The same is true here. The other significant post is this one.



In that post, I mention I already have a Jackery 1000 v2 and some solar panels that we have used to power our full sized refrigerator during outages and that I have used when camping in a tent out of the car. Two of the solar panels I have are suitable for mounting on the R-Pod. I don't have the analyzer figures handy right at the moment, but I can run the full size fridge a full day with regular use on the Jackery (without any solar input). I expect the dorm fridge to use significantly less power.


The Jackery does have pass-through capability. So perhaps the answer is to wire the Jackery in between the shore power input and the distribution center.



Thoughts?



PS. Chuck_S, yes, I will be performing an energy audit on every piece of equipment soon. I just haven't had the chance yet. But given what I already know about my full size fridge, I didn't see the urgency to do it for this fridge.

 

[Chuck_S]

Actually the refrigerator is of paramount urgency as this 120vAC refrigerator pulling power from a 12vDC battery via an inverter will be the primary power consumer in your camper. If it really pulls 1.1aAC (11aDC!) it will kill your battery in 24 or less hours. Next power hog is the furnace.

But we won't know until you determine the power requirements. We also need to know the available amphours in your battery. My "guess" is the power draw is significant. Hope I'm wrong.

-- Chuck

 

[Bob K4TAX]

I had to replace the refrigerator in our other camper. I installed a 5.0 cu/ft 120 volt AC only refrigerator. To accomplish the power and change-over requiremenets I used a 750 watt pure sine wave inverter. It was located near the battery and I use some #2 copper welding cables to connect to the battery. From there I ran the 120 volt inverter output to the back area of the refrigerator.

I built a single relay system using a 3PDT 120 VAC relay. It was wired such that it was powered from the shore power AC. If there was no shore power, the relay switched the refrigerator to the inverter, AND turned on the inverter. Remember, inverters draw some 1 to 3 amps with no load. When shore power was available, the relay switched to refrigerator to shore power and turned off the inverter. Totally seamless and transparent operation.

YES by all means, increased battery capacity is required, for even overnight battery power.

Bob

 

[bikendan]

The fridge is an LIT (Elite) 3.1 Cu.Ft. Compact Refrigerator, model RR001BK. From what I can find online, it looks like it is a replacement purchased from Menard's. I have no idea what was originally in the camper. A fridge powered by AC, DC, or propane would be sweet, but it's not what I have. From what I'm seeing in pictures of other's campers, there was originally a microwave above the fridge. There is just a wooden panel there now.


Thanks,
Andrew

Obviously a previous owner installed this since it's not factory.

 

[TimeOutside]

UPDATE:
I was able to get out to storage for a couple hours today and run a few tests on the refrigerator and air conditioner. I still need to run tests on the furnace, lights, and appliances. I might be able to do that this weekend. Following is a listing of the power supplies I have available and the testing results. Please check my math.

Power Supplies:

Jackery Explorer 1000 v2

• 1070Wh Capacity
• 1500W Output (3000W Surge)
• Pass-through capability (20ms static switch)

Solar

• Qty 2, 100W bifacial solar panels (suitable for mounting on camper)
• Qty 1, 200W bifacial solar panel (portable)
• Experience has shown me that on a partly sunny day, I can fully recharge the Jackery before the day is over using the 200W panel.

Marine Battery

• 1140W (95A RC)

Ford Maverick Hybrid, Equipped with...

• Renology 2000W (4000W Surge) Pure Sine Wave Inverter
• Built-In 400W Modified Sine Wave Inverter
• The inverter will run from the hybrid battery until it discharges to a certain point, at which time the internal combustion engine (ICE) will kick on to recharge the battery. The ICE will run for approximately three minutes. Equipment can run off the inverter until the vehicle runs out of gas.

Testing Results:

Conditions:

• Temperatures in the mid-80s, partial overcast
• 15A shore power supplied to camper via Renology inverter.

Refrigerator:

• Ran from a hot refrigerator until ice cubes started to freeze.
• 61.7 Peak Watts
• 0.058kwh = 58wh in 75 minutes = 46.4 w/hr = 1113.6 w/day
• At this load the hybrid battery would power the refrigerator for about 20 minutes before the ICE would kick on for 3 minutes.

Air Conditioner:

• Ran from a hot camper to the point where 70 degrees was maintained.
• 1419 Peak Watts
• 0.363kwh = 363wh in 30 minutes = 726 w/hr = 17424 w/day
• Note: This seems high to me. Perhaps the initial cool down accounts for the high demand. I'm not sure, but I want to test it again for a longer period of time.

It seems to me the short story is with two 100 watt solar panels feeding the Jackery I should be close to being able to run the refrigerator forever. If I run the 200 watt portable panels, I can do more. And of course, I can always kick on the Maverick to supplement any deficit.

I think the question remains, how do I best incorporate the Jackery into the camper? I'm wondering if something like the solution Bob K4TAX used, but perhaps powering the entire camper (not just the refrigerator).

Thanks,
Andrew

 

[jimmoore13]

So what's your budget for this?
Buying an older camper used suggests a tight budget.

All those who commented previously are on the right track.

The easiest answer is to connect an inverter to your battery and use it to run the fridge. When connected to shore power, the battery charging capacity in your WFCO converter will maintain the battery as the fridge consumes it. No fiddle farting around changing power sources or anything. Plug and play.

For a fridge you don't need a pure sine wave inverter, but it would be nice to have and it would treat your fridge a bit better...especially the electronics that monitor temp and tell the fridge when to run.
Such an arrangement will have several sources of inefficiency. Converting 120 volts AC shore power to 12 volts DC to charge the battery, and then converting 12 volts DC to 120 volts AC to run the fridge. Not a big deal in this case, because the most efficiency-"expensive" transformation is a given if running on battery with no shore power.
Budget choice #1
~ Regular Inverter?
~ Pure Sine Wave Inverter?

Moving up in the world, there are inverters that have automatic transfer switch. This is cool, because shore power tells the transfer switch to select shore power and feed that through the inverter directly to the fridge without all the monkey motion through the battery. But if you pull the plug on shore power, bingo, the transfer switch knows and immediately choose the battery as the power source for the inverter. The "big advantage" is that when on shore power the fridge is not sucking on the battery, which, in turn, needs to be recharged at a steady rate commensurate with the fridge's power demands. Automatic transfer switch inverters cost more, and there is a bit more to hooking them up. And if you are really fancy, you can run all your outlets from the inverter.

Budget Choice #2
~ How fancy of an inverter with an automatic transfer switch?

A big expense will be the rather large gauge cable needed to go directly from the battery to the inverter...either way. Large means #6 or #4 AWG wire to minimize resistance with relatively high current running from the battery to the inverter.

No Budget Choice here - Bite the Bullet on some heavy gauge wire.

Others alluded to your real problem...the battery bank. If you have the garden variety group 24 marine 12 volt battery, it can only deliver about 35 USABLE amp hours (AH) before needing to be charged. You'll need a LOT of battery for this arrangement...and a generator to recharge it if you are out for more than a couple days....maybe more than just 24 hours.

Budget Choice #3
~ How much battery and what kind. We're talking real $$ here. Especially if you set your sights son "lithium"...a whole 'nuther conversation.

This is a very big topic. But there are large fifth wheels out there running residential fridges (you know, 20 cubic feet with ice makers) using a similar arrangement. The catch is that they have HUGE battery banks...say 4 golf cart batteries with a combined usable output of 230 AH. You have 35, and they have 230 or more. Get the picture?

You have much to learn and much to do to make that fridge work for you when boondocking. And I didn't even mention $$$$olar yet.

 

[TimeOutside]

Lots of info...

Jim, I think either you missed my last post or the timing of your post and mine crossed. I have all the power I need. Unless I'm missing something, I believe what remains is to find the best way to connect it to the camper.



Thanks,
Andrew

 

[TimeOutside]

Could it be this simple, or should I have some sort of switch or relay to direct current from the shore power if available then from the Jackery if no shore power is available?

As far as capacity goes, shore power of 120 volts at 30 amps is 3600 watts. The Jackery output is 1500 watts continuous with 3000 watts surge (although realistically I expect it would fall short of 3000). So, I'd need to be careful on what appliances I have turned on when running on the Jackery (like just keeping the air conditioner turned off).

Thoughts?

Thanks again,
Andrew

 

[TimeOutside]

Here's another thought.

[FONT=&quot]I'd have a two-position changeover switch with [/FONT]one input and two outputs[FONT=&quot]. Input would be from shore power as it comes into the camper. One output would direct power to the distribution panel. The other output would direct power to the Jackery (for charging it, if/when needed).[/FONT]

[FONT=&quot]Then I'd have a second two-position changeover switch right after the first having [/FONT]two inputs and one output[FONT=&quot]. One position would take power from the first switch (shore power) and direct it to the distribution panel. The other position would take power from the Jackery and direct it to the distribution panel.[/FONT]
[FONT=&quot]
[/FONT]
[FONT=&quot]With this setup, I can cut the Jackery out of the circuit when I have shore power, or I could direct power solely to the Jackery for charging. If I don't have shore power, I can power the distribution center from the Jackery.
[/FONT]

 

[ppine]

Everything about this post is awkward. Add some solar to power your batteries to accommodate the relentless draw from your refir.

I just bought a 2019 Nash with a propane refir. I was very happy to find one in this configuration. Many modern trailers now have 12 v refirs, but they normally have solar installed to keep the batteries up.

 

[Chuck_S]

The issue is even a full charged battery won't run a 12v refrigerator very long. 400 amphours of battery power at a 10 amp draw will probably provide 20 hours of power before the voltage drops too low to power anything.

Your propane refrigerator will run several weeks on a single cylinder of propane.

-- Chuck

 

[TimeOutside]

Everything about this post is awkward.

I don't understand. What is awkward?

The issue is even a full charged battery won't run a 12v refrigerator very long. 400 amphours of battery power at a 10 amp draw will probably provide 20 hours of power before the voltage drops too low to power anything.

Your propane refrigerator will run several weeks on a single cylinder of propane.

-- Chuck

Folks, I have plenty of power available. The fridge isn't the only AC accessory I want to power. I have the solar which will run the fridge and a few necessary accessories virtually forever. And if it's cloudy I can run everything, including the air conditioner, from the hybrid vehicle for as long as I have gas.

I just need to learn the best way to incorporate the Jackery into the camper. The Jackery is the device receiving the auxiliary power.