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rcksblr's avatar
rcksblr
Explorer
Aug 25, 2020

Need Advice - Refrigerator on separate Inverter

Hi All! I have an older Class A Motorhome (1986 Champion Titan Signature). The previous owner had installed a residential refrigerator that runs on AC/DC only. So No Propane. Its never been a huge issue as we have mostly went to campgrounds where I could plug in. The setup itself is there's a toggle switch from AC to DC for the fridge, so it has it's own inverter and battery. That battery I believe is tied to my larger battery bank that is located up front of the RV. This year we have boondocked a good amount. After this last trip I decided something needs to change as the battery drains very fast. I have to run my generator ALOT/bring a spare battery, etc just to keep the fridge from faulting out. All the things you would imagine needed to keep enough power to run the fridge.

Anyway, I had resound to just buying a new fridge and getting one equipped for Propane. After looking into that, there seems to be a good amount of options out there to stick with the residential fridge setup and just go with Lithium batteries or other upgrades. I am not interested in going solar. I do have an 120W portable solar kit that I hardwired to my battery bank to help maintain things. I am leaning toward just putting a Lithium battery for the dedicated Fridge battery as it's got long life and would charge fast. It's just a large cost initially I want to be sure its a good option.

Does anyone have any advice/input on this? Much appreciated!
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Aug 25, 2020
    2oldman wrote:
    I don't understand your reference to AC/Dc for fridge. A lithium battery is not going to solve your problems, it's still just a 100ah battery from which you can draw a bit more power than an acid.


    There are 3 or 4 types of AC/DC fridges
    ONE: Original type: Absorption cooling unit
    This is the "Standard" propane is an option RV Fridge without the propane options. Nothing fancy sucks over 300 watts when cooling takes a LOT of 12 volt power

    Residential fridge with Inverter Sucks 100-200 watts running

    High effiency what I call "Danfoss" class (Danfoss is ONE of the companies that makes the compressor. not sure the real class name) Draw about 30-45 watts running door closed (Opening door adds 20 watts for the light)

    Both Norcold and Dometic made "RV SIZE" fridges of this type. IF uou do not want to go Propane. that's what I suggest doing. IF you are good with propane.. So am I.
  • 2oldman's avatar
    2oldman
    Explorer II
    Aug 25, 2020
    rcksblr wrote:
    One of the main selling points (Li) for me was the longevity of the battery itself along with being able to charge up quickly when running the generator.
    I'm a lithium man myself, and yes they charge crazy fast and don't care what state of charge you leave them in. My Li pack will probably outlive me.
  • rcksblr's avatar
    rcksblr
    Explorer
    Aug 25, 2020
    time2roll wrote:
    I would not mix the lithium with the other batteries. I would replace ALL the house batteries with lithium. Otherwise you will be managing two different banks with different charging etc. Verify the charging system specs match the lithium battery before you purchase. Even with the increased usable capacity you may still need to increase capacity until you are comfortable withe the power duration. I would want capability of 48 to 72 hours minimum between charging even if you charge daily. This capability for if something goes wrong. You will know more what you need after a few nights off-grid.


    This is something I was going to ask separately. Kudos to you! I'm not expert on this subject so it crossed my mind to change them all for the very reasons you mention. I like the idea and piece of mind knowing we can go some time with just batteries. Just this last trip I had to pull the carb off my Onon generator because it stopped running. Choke was sticking. But boy to replace all the batteries to Lithium that a pretty penny when the batteries cost $900 bucks! Thanks for the input here.
  • rcksblr's avatar
    rcksblr
    Explorer
    Aug 25, 2020
    theoldwizard1 wrote:
    rcksblr wrote:

    Anyway, I had resound to just buying a new fridge and getting one equipped for Propane. After looking into that, there seems to be a good amount of options out there to stick with the residential fridge setup and just go with Lithium batteries or other upgrades. I am not interested in going solar. I do have an 120W portable solar kit that I hardwired to my battery bank to help maintain things. I am leaning toward just putting a Lithium battery for the dedicated Fridge battery as it's got long life and would charge fast. It's just a large cost initially I want to be sure its a good option.

    Does anyone have any advice/input on this? Much appreciated!

    Do you boon dock much ? If so for how long ?

    You still have to decide if you want a DC only refrigerator or do you want a residential unit and then an inverter. The residential refrigerator will cost less, but then you have to adding in the cost of the inverter. Most DC only refrigerators have an optional AC power supply that you can use when on shore power, but that is not adequate for recharging a dedicated battery.

    If you have no interest in an inverter for the rest of your coach, perhaps a separate battery just for a refrigerator but it might be a good option ! If you only boondock for a couple of nights, I think a 30Ah-50Ah refrigerator dedicated lithium battery would be adequate. Buy a dedicated lithium battery charger and wire it, the battery and the refrigerator positive leads together. Same for all of the negative leads together.


    I already have the Fridge. Previous owner put in a Danby 7 Cubic Ft. It's wired to a switch for AC/DC. I also have an 1000W inverter dedicated to the fridge for that setup.

    We don't get out a ton the last couple years as we are a young family. Have newborn and toddler. When we do go, about 50% of the time we boon dock. We just got back from a boon dock trip where we camped 5 days. The Fridge lasted the whole time, but I had to run the generator in the morning and then again in the evening; plus after 3 days I swapped the Fridge battery with an extra fully charged battery I new I would likely need. I can get creative and make it work, but moving forward wanted to get setup so it's a non issue.
  • rcksblr's avatar
    rcksblr
    Explorer
    Aug 25, 2020
    2oldman wrote:
    I don't understand your reference to AC/Dc for fridge. A lithium battery is not going to solve your problems, it's still just a 100ah battery from which you can draw a bit more power than an acid.

    Solar is a really good idea for this problem. In fact, it's about the only idea unless you like hookups all the time or running a generator.

    Here's a few previous posts on the subject:


    pros-cons v. gas2016
    boondock with residential refer 2018
    household refer and inverter2009
    Household refer Class A 2009
    residential fridge- boondocking 09
    Residential refer Class A 2010


    Thank you! Lots of good info in there. I'm not married to Lithium it's just what I found some people had luck with. One of the main selling points for me was the longevity of the battery itself along with being able to charge up quickly when running the generator.
  • time2roll's avatar
    time2roll
    Nomad
    Aug 25, 2020
    I would not mix the lithium with the other batteries. I would replace ALL the house batteries with lithium. Otherwise you will be managing two different banks with different charging etc. Verify the charging system specs match the lithium battery before you purchase. Even with the increased usable capacity you may still need to increase capacity until you are comfortable withe the power duration. I would want capability of 48 to 72 hours minimum between charging even if you charge daily. This capability for if something goes wrong. You will know more what you need after a few nights off-grid.
  • theoldwizard1's avatar
    theoldwizard1
    Explorer II
    Aug 25, 2020
    rcksblr wrote:

    Anyway, I had resound to just buying a new fridge and getting one equipped for Propane. After looking into that, there seems to be a good amount of options out there to stick with the residential fridge setup and just go with Lithium batteries or other upgrades. I am not interested in going solar. I do have an 120W portable solar kit that I hardwired to my battery bank to help maintain things. I am leaning toward just putting a Lithium battery for the dedicated Fridge battery as it's got long life and would charge fast. It's just a large cost initially I want to be sure its a good option.

    Does anyone have any advice/input on this? Much appreciated!

    Do you boondock much ? If so for how long ?

    You still have to decide if you want a DC only refrigerator or do you want a residential unit and then an inverter. The residential refrigerator will cost less, but then you have to adding in the cost of the inverter. Most DC only refrigerators have an optional AC power supply that you can use when on shore power, but that is not adequate for recharging a dedicated battery.

    If you have no interest in an inverter for the rest of your coach, perhaps a separate battery just for a refrigerator but it might be a good option ! If you only boondock for a couple of nights, I think a 30Ah-50Ah refrigerator dedicated lithium battery would be adequate. Buy a dedicated lithium battery charger and wire it, the battery and the refrigerator positive leads together. Same for all of the negative leads together.
  • rcksblr's avatar
    rcksblr
    Explorer
    Aug 25, 2020
    jdc1 wrote:
    100amps/day is what a 20 cubic fridge/freezer uses. One $899 battery will work for a day. You'll need a different charger.


    The fridge is a Danby 7.4 Cubic Feet. Sticker says 344 kWh annually. So if I do the math that is somewhere around 80 Amps/day. Which is a lot, no doubt.

    My thought in this application for the Lithium battery would be that I could run the Generator for a few hours a day to recharge the battery to keep things maintained while camping. I also have the solar panels I could keep plugged into the battery as well while not running the generator. I do have two separate standard RV/Marine batteries (845 CC amps) in the battery bank up front that are tied to the Fridge battery so that would help as well.
  • 2oldman's avatar
    2oldman
    Explorer II
    Aug 25, 2020
    I don't understand your reference to AC/Dc for fridge. A lithium battery is not going to solve your problems, it's still just a 100ah battery from which you can draw a bit more power than an acid.

    Solar is a really good idea for this problem. In fact, it's about the only idea unless you like hookups all the time or running a generator.

    Here's a few previous posts on the subject:


    pros-cons v. gas2016
    boondock with residential refer 2018
    household refer and inverter2009
    Household refer Class A 2009
    residential fridge- boondocking 09
    Residential refer Class A 2010
  • jdc1's avatar
    jdc1
    Explorer II
    Aug 25, 2020
    100amps/day is what a 20 cubic fridge/freezer uses. One $899 battery will work for a day. You'll need a different charger.

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