Rv refrigerator on a inverter

[Blues]

16 hours ago, Ray,IN said:

oldjohnt, my Norcold 1200 two 120VAC resistance heaters draw 380W each.

Are you sure?  My Norcold 1200 has two heaters of 225 watts each, and the Amish cooling unit replacement for it also has two 225-watt heaters.

The thing about absorption (propane/electric) refrigerators on electric is that they are energy hogs.  My Norcold uses about 8 kwh of electricity a day, while a much larger electric residential refrigerator uses about 1.5 kwh/day. 

[oldjohnt]

29 minutes ago, Blues said:

The thing about absorption (propane/electric) refrigerators on electric is that they are energy hogs

That's why I prefer to use LP Gas when I'm driving or dry camping not plugged to shore power. I have used battery and Inverter when driving (especially tunnels or where its forbidden) but I have either alternator or solar power to keep my batteries up. Ive (in 49 years of RVing) owned a ton of  smaller RV Gas/Electric single door fridges that only had one heater.

John T 

[Chad Heiser]

8 hours ago, hemsteadc said:

I think I know what you meant, but, no, it's not 10x 380w.  The wattage doesn't change.

You are correct the wattage doesn't change, but the amperage does (by a factor of 10) when going from 120 volts to 12 volt.

Watts = Volts X Amps

Assuming 380 Watts at 120 volts that would be 3.17 amps of draw

To get the same 380 watts at 12 volts it would be 31.67 amps being drawn (10 times more amps to get the same wattage).  

This does not take into account the inefficiencies inherent in an inverter nor any possible line losses, etc.

This is why I do not recommend using an inverter to run the 120 volt heating element in any RV appliances (unless you have a significant 12 volt infrastructure and solar charging source).  An RV refrigerator or an RV water heater are not as high draw as say a microwave oven, but they tend to run much longer than a microwave oven, thus drawing much more power over time.

[Ray,IN]

6 hours ago, Blues said:

Are you sure?  My Norcold 1200 has two heaters of 225 watts each, and the Amish cooling unit replacement for it also has two 225-watt heaters.

The thing about absorption (propane/electric) refrigerators on electric is that they are energy hogs.  My Norcold uses about 8 kwh of electricity a day, while a much larger electric residential refrigerator uses about 1.5 kwh/day. 

Good catch, thanks. My old memory banks are dusty these days.

Chad Heiser thanks for clearing up the muddy water I created, you stated what I attempted to say.

Edited May 15, 2020 by Ray,IN

[oldjohnt]

   Neighbor Ray, actually I understood what you were trying to say and didn't think it was confusing at all, basically when using an Inverter the 12 VDC battery current to power a 120 VAC load would be approximately 120/12 OR TEN TIMES WHAT BATTERY CURRENT IS REQUIRED VERSUS CURRENT AT 120 VOLTS. That's easy peasey lol.  I knew you didn't think the power (Watts = Volts x Amps) increased ten times. Watts are still Watts, you know that I'm sure........

 There's agreement its best when dry camping a fridge should be run on LP  versus electric  !!!!!!!!!!!!!!

Of course, if the heating element is relatively small, say 300 + watts, NOT a big dual heat element fridge or 500 to 1500 watts huge energy hog like a microwave or heater or coffee pot, if a person has enough battery capacity and re charging capacity like the engines alternator (driving) or solar (driving or dry camped) its feasible to run using an Inverter.

FOR EXAMPLE let use for example (smaller one heat element unit NOT a bigger fridge) fridges heating element requires 350 watts at 12 VDC when running (NOT all the time it cycles) it would draw 350/12 or 29 battery Amps (NOT counting for inefficiency). Sooooooooooooooo if a person had an alternator based charge system capable of that extra 29+ amps above and beyond normal use, it could help run the fridge when driving. SIMILAR if when dry camped (or driving for that matter) he had enough solar to pump 29+ amps into the batteries that would keep up BUT ONLY WHEN SUN SHINES and he would need enough stored battery energy to power it overnight without over discharging the batteries. THAT'S WHY I DON'T RECOMMEND RUNNING THE FRIDGE ON ELECTRIC BUT GAS INSTEAD although  if the alternator has the capacity its not quite as risky (electrical) and maybe safer (maybe even legally required in certain cases)  to use Inverter power instead of gas when driving down the highway............ I have in cases when driving, where I thought it was unsafe or illegal, ran my single heat element fridge on Inverter power but I have 520 Amp Hours of AGM batteries, 1080 Solar Watts (works when driving) and my alternator can if needed supply extra house battery charge. 

Fun and informative thread for us sparkies at least lol

Take care Neighbor Ray, lets meet up after this Conona Beer Virus gets better I drink Millers lol

John T

 

   

Edited May 15, 2020 by oldjohnt

[Dutch_12078]

Just for comparison, the 10.1 cu ft residential compressor fridge I installed in our motorhome lists a maximum running current of 2 amps with a momentary maximum 6 amp starting current. In actual use, it draws ~1.2 amps most of the time, only kicking up to ~1.8 amps for a few minutes when the self defrost system kicks in. It also has a much lower duty cycle than our previous absorption fridge, typically running just 10-15 min/hr. Our 800 watt dedicated inverter and 130 amp alternator easily keep up with it while under way...

[hemsteadc]

15 hours ago, Chad Heiser said:

This is why I do not recommend using an inverter to run the 120 volt heating element in any RV appliances (unless you have a significant 12 volt infrastructure and solar charging source).  

If peeps want to run a lot of high-draw stuff I often recommend 24v or higher to the inverter.  Keeps the amperage down to a reasonable, manageable level.  

[oldjohnt]

1 hour ago, Dutch_12078 said:

Just for comparison, the 10.1 cu ft residential compressor fridge I installed in our motorhome lists a maximum running current of 2 amps with a momentary maximum 6 amp starting current. In actual use, it draws ~1.2 amps most of the time,

THANKS DUTCH I love it when people post actual data related to the discussion. Indeed I have found the same, modern 120 VAC compressor fridges are quite energy efficient. For another comparison, my much smaller 120 VAC dorm size 120 VAC compressor fridge which i USE 24/7 when dry camping or driving (or anytime anywhere plugged or unplugged)  ONLY TAKES 45 BATTERY AMP HOURS A DAY TO OPERATE..  When I'm driving and for whatever reason (certain locations or just for safety sake) I ran my RV LP Gas/Electric fridge on electric sure it worked fine (I have BOTH Solar and/or Alternator to help if needed) but the 120 VAC fridge is still very energy efficient.  My CPAP only requires around 25 Amp Hours per night to operate. 

As always a pleasure sparky chatting with you Dutch

John T

[folivier]

Dutch, just for clarification is the 1.2 amps at 12 volts DC?  Mind telling us which brand and model?

Thanks.

[Dutch_12078]

25 minutes ago, folivier said:

Dutch, just for clarification is the 1.2 amps at 12 volts DC?  Mind telling us which brand and model?

Thanks.

That's at 115 VAC, as it is for the electric mode on most current RV absorption fridges. Our fridge is a Haier HA10TG31SB.

Edited May 16, 2020 by Dutch_12078

[Randyretired]

1.2 amps at 120 vac is what I have measured on our 18 cubic foot residential refrigerator.  We also have a little 5 cubic foot freezer that just barely makes the meter move on my amp meter.  We easily ran both and a lot more on 1000 watts of solar.  I am now adding another 1000 watts of solar to prep for a mini split.

[oldjohnt]

Again, gotta love actual data inputs. THANKS

A 1.2 Amp 120 VAC fridge running off an Inverter would draw something like approximately 13 battery amps.  If you used lets just say 6 hours per day ??????? compressor run time, that would equal  = 78 battery Amp Hours energy consumption. LESS IF COMPRESSOR RAN LESS OFTEN   DUH lol

A 2.0  Amp 120 VAC fridge running off an Inverter would draw something like approximately 22 battery amps. If you used lets just say 6 hours per day ?????? of compressor run time, that would equal 132 battery Amp Hours.  LESS IF COMPRESSOR RAN LESS OFTEN   DUH lol

Based on ambient temp, how often the door was open, insulation, efficiency and how many hours per day the compressor runs is needed to calculate total energy requirements,  but those figures if accurate shows how its indeed possible to power those fridges PROVIDED there's adequate solar and/or alternator charging going on.......  If NOT you're screwed lol

NOTE this comparison IS NOT the same if you were choosing/deciding to run an RV Gas/Electric fridge on LP or battery/inverter, that's well covered above. I still prefer LP operation when dry camping. Like Randy in our small 29 ft Class C with only a modest 1080 solar watts and  520 AH of AGM we can run a small battery inverter 120 VAC fridge 24/7 and nightly CPAP and never have a problem even if its shady or cloudy. 

Take care yall

John T

Edited May 16, 2020 by oldjohnt

[Danandfreda]

This is the info I’ve been looking for. We are trying to figure out the set up on a new fiver. Want to set up for some boondocking with 6 battle born 100 amp batteries. Going with the new norcold 18 cubic foot refrigerator that draws 2.75 amp on dc and 5.0 on ac. So if it’s 10 times 5amps times the 6-8 hours run time. 400 amps per day would 6 batteries be enough to get through a day? Not sure if I’m figuring right and that does not include lights or tv. Think it might be better to run on propane at 2.75 amps. What is the lowest you should run the batteries down before charging? Thanks for any input 

[oldjohnt]

Danandfreda, CONGRATULATIONS on the 6 new Battleborns. Thats 600 rated Amp Hours of energy storage capability wooooooooo hoooooooooooo 

Am I correct in assuming  you intend to run the fridge at 120 VAC using Battery and  Inverter power when dry camping ??? If it were possible to power it using straight 12 VDC (like a 3 way unit, LP, 12 VDC, 120 VAC)  you would be better off as you save the inverter inefficiency losses !!!! Or is the 2.75 DC amps ONLY for control purposes ??? IE 2.75 DC Control + 5 AC power (if on 120 VAC) .

1) If it draws 5 Amps AC when running ????? and you use battery/inverter power,  that requires something like (5 x 11) or 55 12 Volt Battery Amps when running.

2) If say the unit had to run 6 hours per day (NO idea depends on many factors and unknowns)  such would consume 55 x 6 or 330 Amp Hours of stored battery energy (plus whatever DC control current)

3) If I bought new Batteleborns, regardless if they can be drawn down more, I would not make a habit of using more then say 80% or 480 Amp Hours down from a full SOC.  

4) To me if dry camping and you have solar I look at energy storage and availability between the time sun goes down and say 9 AM the next morning. If you don't have solar, then running that fridge 24/7 LOOKS LESS PROMISING ON 120 VAC Id use LP Gas. The best scenario is if you were at 100% SOC when dry camped and the fridge starts its run, if not ??????????? 

5) Sooooooooooo knowing the fridge would require say 330 Amp Hours of energy per day and assuming you know the battery State of Charge and any re charge ability like solar etc and based on what discharge you may choose to tolerate and all your other battery loads YOU CAN NOW  MAKE A SOMEWHAT INFORMED DECISION 

SHORT ANSWER AND OPINION    I would run on LP Gas when dry camping    WHY  ??? If the fridge required 330 Amp Hours and despite your having 600, if you didn't want to ever draw down over 80% or 480 Amp Hours THERES NOT ALL THAT MUCH LEFT FOR OTHER USES   To me its a NO BRAINER use LP gas when dry camping and save that 330 Amp hours for other purposes ALTHOUGH SURE DEPENDING ON IF YOU HAD ENOUGH SOLAR YOU COULD GET BY JUST FINE

NOTE the late model energy efficient 120 VAC Compressor fridges are more energy efficient and subject to size may draw LESS THEN THAT 5 AMPS YOU'RE SPEAKING OF but that's not your question or concern 

Best I have to offer with so many unknowns and variables, Id use LP Gas myself

John T

[Randyretired]

2 hours ago, Danandfreda said:

This is the info I’ve been looking for. We are trying to figure out the set up on a new fiver. Want to set up for some boondocking with 6 battle born 100 amp batteries. Going with the new norcold 18 cubic foot refrigerator that draws 2.75 amp on dc and 5.0 on ac. So if it’s 10 times 5amps times the 6-8 hours run time. 400 amps per day would 6 batteries be enough to get through a day? Not sure if I’m figuring right and that does not include lights or tv. Think it might be better to run on propane at 2.75 amps. What is the lowest you should run the batteries down before charging? Thanks for any input 

How the batteries will be charged can also enter into this but generally absorption type refrigerators  are electric power hogs.  However, these function pretty well on propane.  5 battle born batteries is a good setup and depending on charging (solar?) that's pretty good storage.  When we had an absorption refrigerator I used propane whenever we didn't have hookups and saved the solar power for TV, microwave  and the other electrical requirements. We now have a residential refrigerator, which uses a lot less electricity and is easily powered by solar.  Now if you just will use the batteries for 8 hours or so while driving between campsites the batteries will work okay because the refrigerator will likely not run all of the time.  

[oldjohnt]

12 hours ago, Randyretired said:

but generally absorption type refrigerators  are electric power hog

AMEN to that Randy. I got to thinking one reason that may be true is UNLIKE a compressor powered fridge in which the compressor might only run say (pure guess depends on many things) 6 hours OR WHATEVER per day, the 120 VAC heating element in a LP/Elec fridge might run MUCH LONGER over a day. Just like on LP Gas the flame stays on much of the time, if running on electric the heating element may draw current LONGGGGGGGGGGG PERIODS. I have ran mine (Gas/Elec) on electric and used a KillAWatt meter to measure its power consumption and remember it was HUGE but unfortunately I didn't write it down and forget the exact number grrrrrrrrrrrrr my bad..............

Take care yall

John T

[Danandfreda]

Thanks for the information the recharging will be from a generator at first no solar yet we will have it wired for solar. Trying to decide on generator. Going with Onan  diesel but not sure on size 6000 watt or 8000? The 6000 has 50 amps 8000 has 66.6 I’m assuming that makes a difference on run time to recharge batteries. The 6000 will run 2 ax’s with 1000 watts left, the 8000 will will run both ac’s with 3100 left. I think the 8 is a little over kill. I think our plan will be to run frig on propane and the way I read it it’s 2.75 amps dc on propane. 

[Danandfreda]

We are camping in my brother’s driveway for a week. We now have a drv mobile suite and am recording the amp draw on different appliances as we turn them on to get a rough idea and writing it down. On another note we are plugged in to a 110 gfci plug now and it trips as soon as it is plugged in. We were on 50 amp power last 3 months and no problem. I’ve narrowed it down to the living room circuit ( receptacles, ceiling fan , stereo system). Going to plug stereo into another outlet to rule that out all the outlets were use and one time or another in when hooked up to 50amp power with no problem. Any place that comes to mind to start I’m thinking it’s in the stereo mane a small short? This has done this at 2 different houses while plugged in to 110. Turned all breakers off and turned on one at a time to narrow it to living room circuit 

[Darryl&Rita]

Breaker tripping, or GFCI tripping? There's a different solution for each.

[Danandfreda]

Gfci

[Danandfreda]

Gfci on the house tris when camper plugged in

[oldjohnt]

Danandfreda,

"I’m assuming that makes a difference on run time to recharge batteries'

The time required to charge your batteries depends on the size of your Converter/Charger REGARDLESS if you're plugged to shore power or using a 6000 or 8000 watt generator to operate it.

Was the 50 amp service you plugged to (and had no problems)  GFCI protected ??? 

You have a good plan to disconnect all the RV branch circuits and power them up one at a time to see if you can isolate whats causing the GFCI to trip. It ONLY takes like 5/6 milliamps of fault current and dirt or dust or excess moisture or the slightest fault to trip them. I have seen a GFCI trip due to moisture or dirt AT AN EXTERIOR OUTLET LOCATION on a branch circuit, maybe the stereo or whatever you suspect is on the same branch circuit as a faulty receptacle and it NOT the stereo, is the problem?? Once you isolate the branch circuit that's causing the GFCI trip, then you have to find what appliance or device or receptacle might be the problem.

The genny size is your choice based on your maximum requirements, it never hurts to go too big in my experience even if its overkill. 

John T

[Danandfreda]

Thanks oldjohn I will check on the converter/charger. I pulled the panel off and couldn’t believe all the debris in the wiring. I will clean it out first then check tightness on the terminals, then if it still bad I will pick out an outlet in the middle off the circuit and unwire then turn power on to try to narrow it down. I’ve had to replace 2 outlets already because of wire that arc because they were loose in the rv style receptacle replaced with a residential old work box and receptacle. Not a fan of the push the wire between the blade to make contact. Not sure if the 50amp power was gfci protected it was in a state park and a private park with new service in a county that’s pretty strict on building codes but not sure if it’s required 

[Randyretired]

John's post covers the GFCI problems very well.  I might just add a fault anywhere that allows conductivity between the ground and neutral can be very difficult to find.  As John said it may be be internal to the wiring and outlets.  One place I have found GFCI problems is the electric heating element in water heaters.  This type of problem can appear to be random and the way I found it is by removing all of the neutrals and then reconnecting these one at a time.  

The size of the generator usually has little to do with the time necessary to charge the batteries.   Once the max load of the charging device, usually an inverter charger is met, that is the maximum power that can be transmitted to the batteries.  For our needs we just have a 3,000 watt generator.  We avoid places that would require both AC's and 3,000 watts easily supports our inverter charger. 

[Danandfreda]

Thanks retiredrandy we too don’t want to be anywhere that we HAVE to run both ac’s. I forgot to mention the gfci on the rv never trips. Had this problem before we sold our house when it was plugged in there to 110. It wasn’t instantly gfi tripped there but it would eventually. When hooked up to 50 amp everything was fine and even checked every receptacle with a tester and was good. Ruled out the power cord and 50to 110 power because it only happens on one circuit in the rv. Will investigate more today