12v Electric Fridge Question

[Bcc75]

We just got our new 2023 Globetrotter. It has a Norcold 12v Electric Fridge.
We also have the factory 300w Solar panels and AGM batteries.
Our previous Trailer did not have Solar and we had the 2 way 120v/Propane Fridge, so I'm new to these things.
Can anyone tell me how long the 12v Fridge will run on batteries (from a full charge) before the batteries have to be recharged?. Or better yet, how long can it run with just solar replenishing the batteries? Assuming good solar conditions.
Reason I ask primarily is that I want to be able to turn my fridge on prior to trip and leave the trailer sitting in my yard for a day or so and not have worry about having to plug in to 120v power.
I know the earlier versions of these 12v refrigerators were power hogs but I've heard they have gotten better.

Thanks

[Trekers]

We have done what you want to do several times with great results. We have 380 watts of solar (and 2 AGMs) on our 30' FC and we have started and loaded the fridge days before leaving without plugging in and the batteries stayed strong. The new compressor fridges are much more efficient with batteries than the absorption models were.

[field & stream]

Originally Posted by Trekers

We have done what you want to do several times with great results. We have 380 watts of solar (and 2 AGMs) on our 30' FC and we have started and loaded the fridge days before leaving without plugging in and the batteries stayed strong. The new compressor fridges are much more efficient with batteries than the absorption models were.

I am glad it is working for you, and your experience should be helpful to the OP.

But, it is absolutely not true that compressor fridges are more efficient with batteries than absorption fridges. The opposite is true. There are a number of variables, but it is safe to say that they use several times more electricity.

[vanderwielen]

Originally Posted by field & stream

I am glad it is working for you, and your experience should be helpful to the OP.

But, it is absolutely not true that compressor fridges are more efficient with batteries than absorption fridges. The opposite is true. There are a number of variables, but it is safe to say that they use several times more electricity.

ouch, it is ABSOLUTELY true that a DC fridge is more efficient when using DC vs. an absorption fridge running DC. Here's a youtube video. Scrub to about 4:30 and watch. I can verify his statements.

https://www.youtube.com/watch?v=4DV0bdNtF9w

[azflycaster]

Only a 3 way absorption fridge will run on DC and those are exceptions as most are 2 way (AC or Propane). When running in propane mode an absorption fridge fridge uses very little battery. In fact, the earlier versions used no battery power. The DC powered absorption fridge (3 way) was very inefficient.

[dznf0g]

Originally Posted by vanderwielen

ouch, it is ABSOLUTELY true that a DC fridge is more efficient when using DC vs. an absorption fridge running DC. Here's a youtube video. Scrub to about 4:30 and watch. I can verify his statements.

But not when operating a G/A fridge on LP.

[vanderwielen]

Originally Posted by dznf0g

But not when operating a G/A fridge on LP.

True, but re-read my response.

[GCinSC2]

Originally Posted by vanderwielen

ouch, it is ABSOLUTELY true that a DC fridge is more efficient when using DC vs. an absorption fridge running DC.]

I think it would help if you defined which EFFICIENT parameter you are stating. Like time required to cool the compressor wins hands down.

I’ve watched a few Mark Polk videos but this seemed like a commercial script presentation.

Gary

[field & stream]

As the one who started this back-and-forth, let me clarify my statement that compressor fridges are "not more efficient with batteries" by adding the phrase: "except in the extremely rare case that the absorption (propane) fridge is being run on electricity".


Making the blanket statement that they are more efficient users of batteries is a classic case of cherry picking data to come to a misleading conclusion.


Compressor fridges have many advantages, but efficient use of batteries is not one of them.

[dznf0g]

Originally Posted by field & stream

As the one who started this back-and-forth, let me clarify my statement that compressor fridges are "not more efficient with batteries" by adding the phrase: "except in the extremely rare case that the absorption (propane) fridge is being run on electricity".


Making the blanket statement that they are more efficient users of batteries is a classic case of cherry picking data to come to a misleading conclusion.


Compressor fridges have many advantages, but efficient use of batteries is not one of them.

Correct. I frankly have never seen the value of a 3 way gas absorption fridge. The 12 v mode is counter to any kind of realistic battery management. So is a compressor fridge. UNLESS, one has a very large battery bank, a large capacity dc-dc converter and a large solar system.
I rue the day when gas absorption is no longer available.

All this for my travel and lifestyle over almost 40 years of trailer traveling.

[Doc Foster]

I looked at solar options to keep my batteries charged up over the winter, but with extended days of cloud cover, snow and below freezing temperatures, I decided to go with a battery trickle charger like this - https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I keep my 2 batteries in the garage and hooked up on chargers, never gets below freezing and I can keep an eye on them.

[AgBullet]

Originally Posted by Bcc75

We just got our new 2023 Globetrotter. It has a Norcold 12v Electric Fridge.
We also have the factory 300w Solar panels and AGM batteries.
Our previous Trailer did not have Solar and we had the 2 way 120v/Propane Fridge, so I'm new to these things.
Can anyone tell me how long the 12v Fridge will run on batteries (from a full charge) before the batteries have to be recharged?. Or better yet, how long can it run with just solar replenishing the batteries? Assuming good solar conditions.
Reason I ask primarily is that I want to be able to turn my fridge on prior to trip and leave the trailer sitting in my yard for a day or so and not have worry about having to plug in to 120v power.
I know the earlier versions of these 12v refrigerators were power hogs but I've heard they have gotten better.

Thanks

No one in this thread has actually answered the OP's question. I read the request as wanting to hear practical experience boondocking with 2 AGMs and 300w solar. I'm very interested to know as I have a 23 GT27 on order with the same configuration.

[Boxite]

Originally Posted by Bcc75

We just got our new 2023 Globetrotter. It has a Norcold 12v Electric Fridge.
We also have the factory 300w Solar panels and AGM batteries.
Our previous Trailer did not have Solar and we had the 2 way 120v/Propane Fridge, so I'm new to these things.
Can anyone tell me how long the 12v Fridge will run on batteries (from a full charge) before the batteries have to be recharged?. Or better yet, how long can it run with just solar replenishing the batteries? Assuming good solar conditions.
Reason I ask primarily is that I want to be able to turn my fridge on prior to trip and leave the trailer sitting in my yard for a day or so and not have worry about having to plug in to 120v power.
I know the earlier versions of these 12v refrigerators were power hogs but I've heard they have gotten better.

Thanks

Even if someone were to reply favorably to your question…. Is there any GOOD reason one would desire to START OUT on a trip with depleted batteries..??
Why wouldn’t you simply run a 120 volt extension-cord out to your AS to cool down your ‘fridge for the night before you depart?

[field & stream]

Originally Posted by AgBullet

No one in this thread has actually answered the OP's question. I read the request as wanting to hear practical experience boondocking with 2 AGMs and 300w solar. I'm very interested to know as I have a 23 GT27 on order with the same configuration.

There are so many significant variables that it is hard to answer such a general question. Anecdotal experience, which I don’t have, is helpful.

First we need clear assumptions. Let’s assume there are two 100 Ah lead acid batteries; that means 100Ah usable. Let’s assume that due to variations in fridges and duty cycles due to ambient temperatures the compressor fridge uses 50Ah per day (it could be more). Let’s assume that no other electrical devices are used. Then:

— If there is zero recharging the batteries will be dead in two days.
— If there is ideal solar recharging (30Ah per panel per day), it will go indefinitely.
— If there is minimal solar recharging and/or other demands, then the batteries will decline at some rate.

This is why the extra storage capacity of lithium batteries makes them popular for unplugged use. Even then, a generator will be required for extended stays with unfavorable solar conditions.

[Thonevan]

Apples to Oranges. No need to plug it too early. As long as the suns out everyday the battery will charge enough to run the Fridge.

[skyguyscott]

At some point, the technology will advance to the state where the entire trailer (including interior HVAC!) will be running on electric batteries recharged via solar. We are not quite at that point yet, (certainly not in every use-case in every season in every enironment) but getting closer all the time. And with some very expensive, extensive LI upgrades, it's very possible today in some cases in some environments.

The bottom line answer to the OP is that there may be some occasions where your configuration will last you the camping trip, others not so much.

However, there are a number of things you can do to extend your power/safe cold food storage.

One is to start with fresh, topped off batteries, which means, run some electric power to your rig until ready to depart.

Another is to start with some frozen food and ice (I use gallon jugs frozen solid) in the fridge so it can act as an ice box. This method is so effective that depending on the time of year and shaded camping spot, I can do an entire weekend trip (Friday - Sunday noon) with food safely stored in the fridge with NO POWER at all (minimal fridge door openings). By the time I'm ready to roll home on Sunday, there is still some ice water in the gallon jugs.

[uncle_bob]

Hi

Getting back to what folks normally do:

An absorption fridge running on propane and DC (it needs both) will pull between 0.5 and 1.2A on average depending on the model and features. You can run one a long time on battery plus propane plus solar.

A compressor fridge of the size in the 27' will pull between 3 and 6A on average in normal camping weather. How much depends a lot on both the outside and inside temperature. It also depends on things like how cold you set it, humidity, and how often you dive in to get stuff.

A pair of AGM batteries will typically give you 100AH of usable capacity. They aren't dead at that point. It is best to stop using them there to get a reasonable life out of them.

With no sun and a 6A drain from the fridge, you use 72AH a day. The batteries will run just the fridge for a bit over a day.

If you get down to the 3A number on the fridge, still with no sun (it happens ....) you are ok for a bit over two days.

With minimal "other stuff" being done in the trailer, one and two days are about what you would expect.

How much solar will you get at this site on that day under those conditions? It varies all over the place. Some days a 400W setup on an AS might get <10AH from solar. Other days it might be up above 100AH. Do you sit out in the desert in full sun all the time? you will do better than we do here in the east .... . A "best guess" number for us is 50AH a day.

Tossing in 50AH a day, you loose about "a quarter battery" a day. You might get to 4 days. The very big question is how much power you use for other stuff. Without that number, all of this is not going to be very helpful.

Another unmentioned variable is how well the batteries are charged at the start. Unless you stayed plugged I for quite a while (24 hours), your initial state of charge may or may not be 100%.

Bob

[Scott S]

Oh to have the original refrigerator back in my 1960! No 12V required! When the refrig was replaced we had to run 12V to it. When the day comes that the absorption refrig gives out and it has to be replaced with a 12V compressor refrigerator I will need to alter the trailer...it will need have a charger for the battery...and the battery will need to be upgraded...and it will most likely need more than the one non-standard size battery which it now has...and will need to be relocated...and probably solar added. As originally set up my battery was only charged through the tow vehicle...yup, I know, I live in the stone ages!

[field & stream]

Originally Posted by Scott S

Oh to have the original refrigerator back in my 1960! No 12V required! When the refrig was replaced we had to run 12V to it. When the day comes that the absorption refrig gives out and it has to be replaced with a 12V compressor refrigerator I will need to alter the trailer...it will need have a charger for the battery...and the battery will need to be upgraded...and it will most likely need more than the one non-standard size battery which it now has...and will need to be relocated...and probably solar added. As originally set up my battery was only charged through the tow vehicle...yup, I know, I live in the stone ages!

Yeah, the stone ages, the good old days!

I have a 1962 trailer (15’, non-Airstream) that has a propane fridge, 3-burner stove, oven, heater, water pump, light, roof vent, and tongue jack ……. none of which require electricity. There is no battery in the trailer!

Today, even the Basecamp has a power hungry electric only fridge and a microwave.

[Boxite]

Why all the talk about absorption refrigerators going the way of the dinosaurs?
They still make them and surely one can still order them, even on trailers that are standard 12v….. ?