12VDC Compressor Fridge Data

[jimmoore13]

This is an excellent discussion. I urge the moderators to pin it or flag it in some manner, because it's VERY important for several reasons.

• Dealers send customers off the lot with a group 24 FCLA, and those customers seldom realize what power hogs these fridges are.
• Comments on modifications to enable boondocking are very enlightening...and expensive.
• And the merits of a good, old-fashioned absorption fridge also come through.

When we bought our rig, I refused to look at anything that didn't have an absorption fridge. We boondock exclusively, and in 2020, LiFePo4s were still somewhat novel and about a kilobuck a pop for Battleborns. So we setup with 400 watts of solar on the roof and a couple of GC-2s rated for a USABLE 115 AH. It's a great setup when combined with an absorption fridge. But that wouldn't be enough power for reliable extended boondocking with a 12 volt compressor fridge, unless we ran the genny for extended periods.

Given that the lion's share of rigs are now equipped with 12 volt compressor fridges, this thread is news we can use when envisioning boondocking.

PS. We are gearing up for truly extended boondocking with several important mods:

1. Starlink, so we can conduct our business from camp.
2. Another 200 watts of portable solar to help run Starlink.
3. 12 volt power supply to run Starlink.
4. 12 volt ports scattered about the rig to run our laptops using 12 volt laptop (HP) power supplies.
5. A 44 gallon Barker that will live in my truck bed. I already have the FloJet macerator pump.
6. 30 gallon freshwater tank and tranfer pump to allow easy refills of the fresh tank.

This probably wouldn't be an option if we had a 12 volt compressor fridge.

Thank you!!

[fanrgs]

Jim, we live at only 5700' in Colorado, not 8300', but we dry camp and boondock frequently with our 12v fridge.

With 350w of solar and 220 Ah of Li batteries, we tested the fridge for 5 days running only on solar while parked at the house. During that period, we froze tap water in the freezer and took temperature measurements inside the fridge and of the tap water in a pitcher in the fridge. No other power drains were on at the time except the CO-propane detector. But it satisfied me that we could go for several days with the fridge keeping the ice cream frozen and not becoming milk shakes like it did with our previous two propane-120vac fridges. So, we are VERY happy with our 12v, 10 cu. ft. Norcold fridge!

And thanks to Jlangford for giving us real numbers, unlike my qualitative testing.

[CasaDelLobo]

On my Wolf Pup 16 FQBL I have 400W of solar on the roof and 400ah of Li. Battery. I never turn off the 12v fridge until I store it for the winter. I can run my toaster oven, (took out the microwave), and I have gotten the A/C to run on low cool all off my 3000w inverter. I discovered that if I use a 20 amp adaptor plug with my original 30 amp cord plugged into the inverter it all works through the shore power inlet. So far, no problems. The bigger issue with the Wolf Pup is the holding tanks, too small for more than a couple of days.

[jimmoore13]

Originally Posted by fanrgs

Jim, we live at only 5700' in Colorado, not 8300', but we dry camp and boondock frequently with our 12v fridge.

With 350w of solar and 220 Ah of Li batteries, we tested the fridge for 5 days running only on solar while parked at the house. During that period, we froze tap water in the freezer and took temperature measurements inside the fridge and of the tap water in a pitcher in the fridge. No other power drains were on at the time except the CO-propane detector. But it satisfied me that we could go for several days with the fridge keeping the ice cream frozen and not becoming milk shakes like it did with our previous two propane-120vac fridges. So, we are VERY happy with our 12v, 10 cu. ft. Norcold fridge!

And thanks to Jlangford for giving us real numbers, unlike my qualitative testing.

Most definitely, it can be done, but only with considerable additional investment...as you describe. Also bear in mind that, on cold nights, your furnace will take a considerable bite out of your battery bank. Your LiFePo4s are good for about 175 AH usable. If, in the summer, you are camped at altitude, during the day, inside temps on the rig might reach 70 to 80 degrees. Your fridge will work. Let's assume the fridge will eat 60 AH on one of those days. But in the Rockies overnight, you might need to run the furnace. For giggles, let's assume 10 amps, a 50% duty cycle, and 9 hours of run time to cover taking the chill off inside before bed and 8 hours of sleep. That's another 45 AH. Now add in another 10 to 15 AH for things like lights, running the awning in and out, and so on. So, in 24 hours, you've eaten about 120 AH out of 175. Next, assuming a bright, sunny day with no shade on the panels, your 350 watt solar array might replace 80% of that.

Yes, you can go quite a while with the excellent setup you have. But if you drove off the dealer lot with the group 24 marine battery your dealer routinely provides and no solar, you wouldn't make it through the first night.

These 12 volt compressor fridges are becoming the standard of the industry. I expect absorption fridges to become obsolete or extra-cost options. And the compressor fridges are superior in many ways. But, while my rig could survive for extended periods with nothing more than a 100 AH lead acid battery and short runs of the genny, one of these fridges would crush the battery in a day.

The message is that if you own a compressor fridge and plan to boondock, you're going to need to drop at least a kilobuck on mods to make it work. And let's not forget that all the solar in the world won't handle these loads in the PNW or Central NY...where solar gain is minimal by comparison to sunny Colorado.

I'm not disagreeing with you. I just want the uninitiated to fully grasp the significance of this industry-wide change. If you do nothing but go to RV parks with hookups, you won't notice or care. But if you pull the plug, you'd better have one helluva lot of solar and battery...as you do.

PS. We love our ice cream. Our absorption fridge actually keeps it colder than the fridge at home. One thing we do is turn on the fridge in the spring and shut it off in the fall. It runs all summer. At home on shore power, and about 12 hours before hitching up, I switch to propane. Last year, I didn't need to defrost. The year before I did. I just make sure the fins inside are clear of ice and that little slider thingy in the fins is in the right position. The freezer is actually too cold.

[NJKris]

Originally Posted by jimmoore13

Most definitely, it can be done, but only with considerable additional investment...as you describe. Also bear in mind that, on cold nights, your furnace will take a considerable bite out of your battery bank. Your LiFePo4s are good for about 175 AH usable. If, in the summer, you are camped at altitude, during the day, inside temps on the rig might reach 70 to 80 degrees. Your fridge will work. Let's assume the fridge will eat 60 AH on one of those days. But in the Rockies overnight, you might need to run the furnace. For giggles, let's assume 10 amps, a 50% duty cycle, and 9 hours of run time to cover taking the chill off inside before bed and 8 hours of sleep. That's another 45 AH. Now add in another 10 to 15 AH for things like lights, running the awning in and out, and so on. So, in 24 hours, you've eaten about 120 AH out of 175. Next, assuming a bright, sunny day with no shade on the panels, your 350 watt solar array might replace 80% of that.

Yes, you can go quite a while with the excellent setup you have. But if you drove off the dealer lot with the group 24 marine battery your dealer routinely provides and no solar, you wouldn't make it through the first night.

These 12 volt compressor fridges are becoming the standard of the industry. I expect absorption fridges to become obsolete or extra-cost options. And the compressor fridges are superior in many ways. But, while my rig could survive for extended periods with nothing more than a 100 AH lead acid battery and short runs of the genny, one of these fridges would crush the battery in a day.

The message is that if you own a compressor fridge and plan to boondock, you're going to need to drop at least a kilobuck on mods to make it work. And let's not forget that all the solar in the world won't handle these loads in the PNW or Central NY...where solar gain is minimal by comparison to sunny Colorado.

I'm not disagreeing with you. I just want the uninitiated to fully grasp the significance of this industry-wide change. If you do nothing but go to RV parks with hookups, you won't notice or care. But if you pull the plug, you'd better have one helluva lot of solar and battery...as you do.

PS. We love our ice cream. Our absorption fridge actually keeps it colder than the fridge at home. One thing we do is turn on the fridge in the spring and shut it off in the fall. It runs all summer. At home on shore power, and about 12 hours before hitching up, I switch to propane. Last year, I didn't need to defrost. The year before I did. I just make sure the fins inside are clear of ice and that little slider thingy in the fins is in the right position. The freezer is actually too cold.

My absorption freezer actually runs at about -8°F. But fridge struggles to stay cold when it's hot out. Just installed t-stat controlled cooling fans between back of unit and ventilation grates, and this hard wired circulation fan that I'm hoping will negate need for little battery operated Camco fan, and it supposedly keeps ice from forming on the fins.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I like the slim form factor, clips right to the fins. Fan pulls air from front and pushes it back and down across fins.

[Aussieguy]

Actual camping 2 adults South Florida
12v Fridge full of food drink ice cream etc

Wooded campground lots of shade
There is electricity but I am continuing to try and see when do we really have to use shore power or generator…. So my converter remains OFF

Cloudy travel day yesterday batteries went down to 60% overnight

This morning … solar production stopped discharging the batteries at 8am

9:30 am panels producing 20amps
16amps is going into battery the remainder is being consumed by fridge etc

Estimate 3-4 hours until battery is 100% again

[Harbs]

How would I determine the amp draw from my Magic Chef 12v DC refrigerator? My User's manual says it's a Model MCDCR45G-R but cannot find that model on MCA's website.

[Half Ton Heavy]

Originally Posted by Harbs

How would I determine the amp draw from my Magic Chef 12v DC refrigerator? My User's manual says it's a Model MCDCR45G-R but cannot find that model on MCA's website.

A great way is to a shunt/coulomb counter. I strongly recommend either a victron smart shunt or victron BMV712. There are cheaper brands, but victron is top of the heap in my opinion.

[tomkatb]

The expression “it depends” is very important.

Been an engineer a long time. Read thousands of pages of specifications.

Learned to lie with charts and graphs.

My observations.

Where you play matters. We are in the Midwest. It rains a lot. We have lots of clouds and trees. Solar is iffy.

Our fridge is a 13.4 cu ft gas/electric. Not installed in the best manor as are most rv fridges of all kinds. Had an Amish fellow fix it. Compressor fridges are designed to be free standing. Most are not.

The manufacturers save a boat load of money on a compressor fridge. If the owner pays that much difference for solar and batteries, today, then the performance is pretty similar. In my case it would be about $3,000.

So in most cases it is a wash.

Very recently the price of lithium has dropped nearly 50%. Changes the game.

Today the waste tank storage is becoming the issue in most cases.

So it depends.

We can boondock 4 days on batteries alone. Charge up midweek. Tow to a paid site to dump the waste tanks at the end of the week. 1000:watts of solar would work to recharge, sometimes. It depends. Hate the idea of drilling 30-40 holes in my roof.

Too many folks find this out the hard way.

[Aussieguy]

To measure current

a) DC Multimeter with clamp ... you can use it for other stuff too
but you have to locate enough wire to clamp around if you trying to localize the measurement to a specific device. or just measure at battery cable to see total being drawn /charged

b) Shunt can be used on Lead acid or lithium

c) Bluetooth to lithium BMS ... if you got multiple batteries in parallel each will share the discharge eg.... 2 batteries @ 5amps = 10 load

I opted for the bluetooth because you can see the individual cell balance data and adjust some battery parameters