Residential refrigerator and batteries

[CWG]

My Columbus has two 12 volt batteries and a converter for the residential refrigerator. When the batteries have been fully charged how long can I expect them to last operating the refrigerator alone.

[TURBS]

Inverter not converter.

What size batteries?


2015 Columbus 320RS
2008 2500HD Duramax
2015 nights camped "34"
2016 nights camped "10"

[lbrjet]

Depends how much it runs in an hour. Say you have 100 amps in each battery. If you want your batteries to last any length of time then don't discharge them under 50% so you really have100 available amps before recharging. Fridge probably uses about 4 amps AC so that equates to 40 amps DC. If it runs 15 minutes each hour then that is 10 amps per hour for a total of 10 hours. If it runs 5 minutes each hour you can get 30 hours.


2010 F250 5.4L 3.73
2011 Flagstaff 831FKBSS
Equal-i-zer 4pt 12K

[phillyg]

I got 17 hours with two 12v cheap hybrid batteries, still pulled in six slides but then didn't have enough juice to retract the 6-point levelers.

[Havasu Bill]

I have a Frigudaire Gallery in my 3250 Cardinal. I upgraded the batteries to 4 6V Trojans. If I have them fully charged before bed I'm down to 50% charge 10 hrs later. I tried it overnight with just one bank and they were completely drained in the morning.
This fridge pulls about 800w per the manual so I need my 2 Honda 2000 generators a few times a day plus I have a 400W solar panel on my roof.

[CWG]

Thank you for the replies. My batteries are 700 Intersate Marine and both are drained in approximately 5 hours. So back to the dealer to see what he can do for me.

[lbrjet]

800 watts is a 66.6 amp draw. That will drain batteries pretty fast.


2010 F250 5.4L 3.73
2011 Flagstaff 831FKBSS
Equal-i-zer 4pt 12K

[ScottBrownstein]

Originally Posted by lbrjet

800 watts is a 66.6 amp draw. That will drain batteries pretty fast.

Sure 800 watts is a lot, but you need to consider the duty factor and you can get that from the Energy Star rating of your unit.

Energy Star

Measurements taken at Ambient Temp of 90 F
Annual Power Usage is 539 KWH/Year
At 100% running this would mean 8664 KWH/Year
Thus it really runs 6% of the time...
At 6% Duty Factor it uses 1477 WattsDay
At 6% Duty Factor it 62 Watt Hours, which is about 5 amps average load. That would be 10 hours for a single 100 AH battery to 50%, which pretty much matches what many report.

[lbrjet]

I don't know of any fridge that runs only 6 percent of the time. Maybe on a setting of 1.


2010 F250 5.4L 3.73
2011 Flagstaff 831FKBSS
Equal-i-zer 4pt 12K

[ScottBrownstein]

Originally Posted by lbrjet

I don't know of any fridge that runs only 6 percent of the time. Maybe on a setting of 1.

Well the DOE is pretty difficult about Energy Star numbers. All of my data is taken directly from the Energy Star test requirements, including the ambient temperature spec. The power dissipation is directly from their reefer specifications and the Energy Star value is right off the sticker. Not really any way to figure it differently from an math point of view. Of course, when you start up the duty factor is more like 100% for maybe 6 or 8 hours.

Besides, the 6% number works pretty well with everybody's experience with a reliable battery and a good inverter...so...where is the problem? Frankly I would have never guessed as low as 6% and most of these units don't have numbers anymore, they have temperature settings. Mine is on 0 degrees for the freezer and 40 degrees for the reefer portion.

[jeepin1]

Great question, I am a little surprised just picked up our 3250 and have been wondering this also not real happy with the answers, so Havasu Bill with solar panels and 6v batteries you still only get 10 hours, wow that's barely over night, I would like to have the option of dry camping that really puts a damper on that.
Other than a generator I wonder what other options there are more batteries I guess.

[ScottBrownstein]

I have 4 12 volt batteries on my 335 and can go close to 24 hours, which pretty much matches the calculations that I posted. I think something is wrong with Havasu Bill's setup, especially adding 400 watts of solar to the mix. He should be doing better, unless he has kids that leave the door open a lot when he has a rainy day with no sun and they play video games all day with their Playstations hooked up to an inverter. Might also question fully charged if he has been out for a while since running a generator takes a long, long time to get to fully charged.

[jeepin1]

Well, Scott that sounds a little better I was planning on putting 3-12v batteries in with solar, 24 hrs is a little better also with solar that could get you through a little while without running a genny all the time I guess.

[ScottBrownstein]

Originally Posted by jeepin1

a little while without running a genny all the time I guess.

Solar is almost essential if you aren't connected to 110 volts for days at a time. You can run the genny for a few hours, but that will never get you back to 100% SOC. Solar is the ticket, even if you aren't boondocking. Day in and day out it pumps charge back into the batteries...and has a really good possibility of keeping you near 100 percent. I have a Trimetric and I know how much power comes out of my bank. If the specific gravity or voltage is lower than the Trimetric predicts, that just means that the batteries, while rated for some AH capacity, are really no longer able to store what they were spec'd for. Sure they will come up to a good resting voltage and SG, but drawing 25% will drop them closer to 50 or 60 percent. I will replace my 12 volt batteries with 6 volt golf cart units when I can't live with the ones that came with the coach. My experience with 6v units being able to hold rated capacity for years has been really good. 12 V units just aren't that good over time.

[CWG]

My refrigerators was set at -1 and 36. I will change the settings to see if I get more time out of the batteries.