Electric Refrigerator and Batteries

[Larry1492]

Getting ready to pull the trigger on a 2023 Flying Cloud and I’m looking for some advice. What kind of batteries and size is everyone using and how long can you run the newer electric only refrigerator on those batteries?

If I can get two or three days I’m good. Wondering if AGM will do it or should I pop for lithium. Mostly I get sites with electric and except for a couple of long weekend trips every year.

[jeffb831]

The current refrigerators, along with minimal usage and parasitic loads in the trailer, will use almost all the capacity of 2 AGM batteries (~100Ah usable) within 24 hours.

The other part of the equation to consider is how are you planning on recharging the batteries? Solar? Generator? Connections to shore power only?

[100954]

We picked up our 2023 Flying Cloud 23 FB Twin a month ago and are planning to take it out for the first time later this week. We purchased the solar package and the lithium batteries. No one at the dealership was able to tell us with any clarity how long we can expect the refrigerator to run using the solar. Too many variables. So we’ll find our the first time we go off grid, which won’t be until later this summer. One person at the dealership did tell us if the batteries get too low, plugging into our pickup for 20 minutes will recharge the batteries. I find that hard to believe. There are people on this forum who are far more knowledgeable about solar/lithium than anyone at the dealership we purchased from.

[field & stream]

I agree that one day is about it without lithium, but without a solid recharging system even two lithium batteries may not go more than two days. Modern Airstreams, despite the implications of the words a photos in their advertising, are not designed for unplugged camping. And the person at the dealership who told you that “plugging it into your pickup [whatever that means!] will recharge the batteries” is grossly misrepresenting reality.

At least two things about your case are important for us to know to be more helpful: what size trailer and refrigerator, and what is your style of use. For example, are you energy frugal campers or do you want all the comforts of home?

There are several threads already that discuss the issues at length; use the search feature for “electric only fridges “.

[Trons4u]

We have three 100ah lithium and an Vitrifrigo DP2600 12/120v and I can get about 4 days off grid before they are down to about 20% and then charge them up with generator.
Solar is on the list for this year.

[Trekers]

We have the 10 cu foot Norcold in our 30' Flying Cloud. We went for a week with no problem on 2 AGM batteries, 380 watts of solar and a lot of sun everyday. There are a lot of variables to consider in all scenarios though.

When people say the modern trailers eat AGMs, make sure you find out what rig they have, how much tech its running, what their power usage is like, etc. Boondocking requires more power management on the users' part no matter what system you have. I'd say try things out with AGMs before you spring for lithium just because they're all the rage right now.

[jimdelane]

Other than the air conditioner, the refrigerator is the biggest energy user. Depending on the size, it will draw 60 to 100ah per day.

It used to be that a AGMs were the cheaper alternative.
That is no longer true.
A cheap 100ah Group 31 AGM deep cycle battery will cost about $190. You will need 2.
An expensive 100ah Group 31 AGM deep cycle battery (Lifeline) will cost about $440. You will need 2.
A cheap 100ah Group 31 LFP deep cycle battery will cost about $350. You will need 1.
A expensive 100ah Group 31 LFP deep cycle battery (Battleborn) will cost about $890. You will need 1.

Depending on the battery bay, you may be able to fit in a 200ah, 300ah, 400ah or 470ah battery.

Based on 100ah capacity consider the following:
AGMs have 12v @ 50% discharged and should not be discharged below 50% for maximum cycle life.
100ah AGM @ 50% = 50 usable amp hours. It takes 2 batteries to get 100ah of usable energy.
All lead acid batteries, including AGM, should be brought up to minimum 90% daily to prevent sulfation and provide maximum cycle life.
A standard 12 volts AGM battery can carry up to 500 cycles of charge and discharge.
AGMs charge slower. There is a 20-25% efficiency loss due to the electrolyte chemical process. of 100w of incoming charge, 80 watts goes into the battery. Use of a PWM solar charger will cause another 25% efficiency loss so the 100w ends up putting 60w into the battery.
Bulk charge is to 80% and absorption is 80-100%. Absorption charge is at reduced amps and voltage so as not to cause the electrolyte to overcharge and gas. AGMs are a VRLA or valve regulated lead acid. When overcharged, corrosive gas will form and will vent. Unlike flooded LA batteries, there is no way to replace the water so overcharging will dry out the electrolyte and cause premature failure.
AGMs are heavy and weigh about 65lbs each.

LFP/LiFePO4 (lithium iron phosphate) have over 12.8v @ 50% discharged. The discharge curve remains flat through out discharging with over 12.5v @ 90& discharged.
Because of the higher constant voltage, refrigerators, motors, inverters and compressors run cooler and more efficiently.
LFP can be fully discharged but for maximum life, LFP should not be discharged more than 80%.
LFP can be partially discharged indefinitely without damage to the battery. Keeping the battery charged between 40-80% will provide maximum cycle life.
A standard 12 volts LFP battery can last 3000 to 5000 cycles of charge and discharge.
LFP charge faster. There is a direct ion exchange. very watt that goes into the battery is absorbed. Use of a PWM solar charger will cause another 25% efficiency loss so a MPPT solar charger with 99% efficiency is recommended.
Lithium batteries weigh about 30lbs.

Generally the factory inverter chargers installed have a LFP option. It is recommended to install a coulomb based battery monitor. With AGM, voltage is an indication of battery capacity state-of-charge. With LFP, the voltage will remain high until just before you run out. Victron has a SmartShunt battery monitor for about $120 which is bluetooth , so you monitor it on your smartphone.

[Tyler2you]

Probably a dumb question, but does the "electric" refrigerator in the newer trailers always run on 12v?

Or, is there some kind of automatic switch over that goes seamlessly from 120v to battery when shore power is disconnected?

[100954]

My understanding is the refrigerator is 12 volt, period. Not 12 volt and 129v. When you are connected to shore power your converter charges the battery thus allowing the refrigerator to continue to run off the battery. But there are more knowledgeable folks than I on this forum that can confirm or correct that.

[Larry1492]

Originally Posted by Trekers

We have the 10 cu foot Norcold in our 30' Flying Cloud. We went for a week with no problem on 2 AGM batteries, 380 watts of solar and a lot of sun everyday. There are a lot of variables to consider in all scenarios though.

When people say the modern trailers eat AGMs, make sure you find out what rig they have, how much tech its running, what their power usage is like, etc. Boondocking requires more power management on the users' part no matter what system you have. I'd say try things out with AGMs before you spring for lithium just because they're all the rage right now.

Thanks for the reply. I boon dock a couple long weekends a year, other than that it’s full hookup sites. Sounds like it’s included Agm’s might work for what I need. If the don’t I can upgrade to lithium later.

[field & stream]

[QUOTE=Larry1492;2675454]Thanks for the reply. I boon dock a couple long weekends a year, other than that it’s full hookup sites. Sounds like it’s included Agm’s might work for what I need. If the don’t I can upgrade to lithium later.[/QUOTE

Note that your thanks comment was to someone who has 380w of solar (much more than Airstream supplies) and had lots of sun for the period which is not always the case. If you don’t have those your results will vary.

[Tyler2you]

Originally Posted by 100954

My understanding is the refrigerator is 12 volt, period. Not 12 volt and 129v. When you are connected to shore power your converter charges the battery thus allowing the refrigerator to continue to run off the battery. But there are more knowledgeable folks than I on this forum that can confirm or correct that.

Figured it out after looking at the electrical schematic for my trailer and fridge manual. It's auto switching between 12v and 120v.

[Trekers]

Originally Posted by Tyler2you

Probably a dumb question, but does the "electric" refrigerator in the newer trailers always run on 12v?



Or, is there some kind of automatic switch over that goes seamlessly from 120v to battery when shore power is disconnected?

Not a dumb question. Apparently, Norcold makes AC/DC fridges and DC fridges. In our 2022, we have the DC fridge, so even when plugged in to electric, it's running directly off the batteries. AC/DC would make more sense, especially on long-term outings, but it is what it is.

[Trekers]

Originally Posted by Tyler2you

Figured it out after looking at the electrical schematic for my trailer and fridge manual. It's auto switching between 12v and 120v.

Maybe. I thought ours was until we had to pull it for maintenance and there is only a 12-volt wiring. There is an outlet behind it but no plug plugged into it.