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Author Topic: Dry camping with residential refrigerator  (Read 4301 times)

OnSabbatical

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Dry camping with residential refrigerator
« on: April 15, 2016, 04:30:40 PM »
We're driving a large fifth wheel (43 feet) with a large residential refrigerator (whirlpool, if that maters). We only have two 12 volt deep cell batteries.

So I have a few questions:

1. What would be the most cost effective way to equip our RV to boondocks for at least 48 hours. I'm less concerned about air conditioning or microwave, btw, than keeping the refrigerator running. We can live without air conditioning, but we keep a lot of meet in the freezer.  How many batteries would we need? Generator or Solar panels? How much weight would all this add to the RV?

2. Would it be possible to go two days on battery power alone? If so, how many and what size would we need?

Thanks for any thoughts you might have.
F350, Turbo-Diesel, DRW
Sandpiper 371 REBH

Cant Wait

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Re: Dry camping with residential refrigerator
« Reply #1 on: April 15, 2016, 05:59:50 PM »
All I can do is give you our experience with our residential Maytag.  We have no solar,  a 2800 watt Magnum inverter,  6 group 31 AGM batteries, and an 8KW generator.  With this set-up we run the generator in the AM while brewing coffee, cooking etc for about an hour, then again in the evening for another hour or so.  This keep the batteries good for a 4 day boondock we did.
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prfcdoc

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Re: Dry camping with residential refrigerator
« Reply #2 on: April 15, 2016, 06:21:07 PM »
I could be wrong but I think that you will find that most everyone will say "it depends". To have all of the essentials going, depending on how energy efficient your Whirlpool is, I would guess that you should have, at the very least, a couple (preferably 4) true deep cell 6 volt golf cart batteries or the equivalent. I don't know if your 12 volt, deep cell batteries are true deep cell or if they're marine hybrids. The most important thing is the number of amp hours they can store. Check out the forum library on batteries. Adding solar would make them last longer--most of all on sunny days. A generator can make them last indefinitely BUT you have the noise and, potentially, the neighbors, to worry about. You can get a loud, heavy, gas guzzling, construction type generator for just 3 or 4 hundred dollars that would do the job. You could get a 2000W inverter generator for just a bit more. Solar is complex and, unless you want to learn a whole new system, can be somewhat challenging. I spent the past two years maintaining a battery bank and have learned a lot. I've killed a couple of batteries through neglect and learned that four, 12 volt SRM-27 marine/rv deep cycle batteries won't run much of anything unless well maintained recharged every day.
Bob & Kathy
Saving and researching for our future extended road trip.
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OnSabbatical

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Re: Dry camping with residential refrigerator
« Reply #3 on: April 15, 2016, 07:09:25 PM »
So I researched my refrigerator and was told it pulls 1800 watts and Whirlpool says a generator should be at least 2300. I'm considering now getting two 2000 watt inverter generators, either Honda or Yamaha. I'm guessing then we could run our AC when needed too. I was hoping I could get away with just one, but it looks like not.
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Betty Brewer

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Re: Dry camping with residential refrigerator
« Reply #4 on: April 15, 2016, 07:38:50 PM »
I know you know this  but things will stay cold  a lot longer if you never open the  door to refrig and let cold air escape or warm air in. We  keep a remote thermometer inside refrig  compartment and  freezer compartment so we  get readings without opening the door.

 We have a battery operated Chaney thermometer and it gives us a reading for  inside  compartment and inside freezer.  It also gives a beep beep beep if temp falls outside parameters you set.  Why not do some testing  before you  make an  investment.  Leave power off a while and see what you get.

We are  now hooked up to power and the refrig reads 35, the  freezer  -2.  so if power were  out it would take some  time for freezer to  come up to  above freezing if  door is not opened.
I am not the electrician in family but hubby has taught me how to read the gauges. We do a lot of boondocking however  we do run generator  a couple hours in am and an hour in pm.  This while we use all other electronics, tv, lights, phone chargers and maybe just maybe the vacuum!
Betty Brewer

see where we are

OnSabbatical

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Re: Dry camping with residential refrigerator
« Reply #5 on: April 15, 2016, 08:24:15 PM »
My batteries are rated at 80 am hours. And the fridge is 15 amps. With two batteries that's 160 amp hours, so they should be able to run the refrigerator for abou 10 hours, is that correct? But that just means when the compressor is working right? And I read somewhere that you shouldn't allow deep cycle batteries to go below 50%, so really, together they are good for about 5 hours of steady usage?
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Sun2Retire

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Re: Dry camping with residential refrigerator
« Reply #6 on: April 15, 2016, 08:57:06 PM »
My batteries are rated at 80 am hours. And the fridge is 15 amps. With two batteries that's 160 amp hours, so they should be able to run the refrigerator for abou 10 hours, is that correct? But that just means when the compressor is working right? And I read somewhere that you shouldn't allow deep cycle batteries to go below 50%, so really, together they are good for about 5 hours of steady usage?
The experts will weigh in shortly but you're mixing 12 volt amp hour capacity and 120 volt amp draw. Using my amateur math, I think you'd have to work it out like this:

Fridge draws 15 amps at 120 volts which works out to the 1800 watts you mentioned previously. However, for the batteries to produce 1800 watts from 12 volts (lets use 13 for a fully charged battery) you'll see 138.46 amp draw by the inverter from the batteries (138.46 X 13 = 1800). By my math that gives you just over an hour to get to 50%. And at high discharge rates you'll reach the 50% level with fewer amp hours drawn than with a slow discharge.

I have an absorption fridge so you'll want to hear from the many people here that have residential fridges and can give you better answers. I believe most of them probably have in the vicinity of 2-250 amp hours usable to 50%, or more (+ solar). And it seems like most report lower power draw than 15 amps - maybe that's a peak/start number.
« Last Edit: April 15, 2016, 10:49:51 PM by Sun2Retire »
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JiminDenver

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Re: Dry camping with residential refrigerator
« Reply #7 on: April 15, 2016, 09:40:35 PM »
With 750w of solar and 675 Ah of battery we can run a small A/C or mini fridge, even the microwave for 10 minutes or so. That's peanuts to a full sized fridge running 24/7, I'd have to start running the generator again.

Lou Schneider

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Re: Dry camping with residential refrigerator
« Reply #8 on: April 16, 2016, 12:43:34 AM »
The easiest way to see how much electricity your refrigerator uses is to get a Kill-A-Watt meter, plug the refrigerator into it and see how much electricity it uses over 24 or 48 hours.

Then you can size your batteries accordingly.

The K-A-W plugs into an outlet, then the refrigerator plugs into it. It's available at most hardware stores for about $20.

If you can't see the outlet behind the fridge, plug the meter into an outlet where you can see its display and run an extension cord to the refrigerator.
« Last Edit: April 16, 2016, 12:47:16 AM by Lou Schneider »

Kevin Means

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Re: Dry camping with residential refrigerator
« Reply #9 on: April 16, 2016, 03:18:16 AM »
I did exactly what Lou suggested when I was trying to determine how much solar power and battery capacity I'd need to boondock in the winter months in the Southern California and Arizona deserts. We have a large 22 CF residential fridge, three entertainment centers, a 12 cup AC coffee-maker that we use every morning, a few amps of phantom loads and a 2800 watt inverter that powers everything. I wasn't too concerned about our lights, because they're all LED, but incandescent bulbs can make a difference.

Sunshine permitting, I wanted a rooftop solar array (flat panel) that would be large enough to fully charge our house batteries each day, without having to run the generator, and I wanted a battery-bank with enough AH capacity to run all those appliances for 24 hours on a full charge. Here's what I ended up with;

I had to add two additional house-batteries for a total of eight. They are 105 AH Group 31 AGM batteries (total capacity 840 AHs.) I installed an 80 amp MPPT solar controller, a Trimetric RV 2030 battery-monitor and six 160 watt solar panels (960 watts total.) In the winter, with the low solar angle and flat panels, that's just enough solar power to fully charge the batteries by about 3:00 PM. If I were to tilt the panels, I could probably get away with 600 watts, but I'd still need the extra battery capacity. In the summer, when the sun is overhead, I'm fully charged by noon.

Kev
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Towing a Jeep Rubicon Unlimited LJ or an Acura MDX
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(Can't wait to spend more time RVing)
Lakeside, California

Sun2Retire

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Re: Dry camping with residential refrigerator
« Reply #10 on: April 16, 2016, 07:08:44 AM »
Here's what I ended up with;

I had to add two additional house-batteries for a total of eight. They are 105 AH Group 31 AGM batteries (total capacity 840 AHs.) I installed an 80 amp MPPT solar controller, a Trimetric RV 2030 battery-monitor and six 160 watt solar panels (960 watts total.) In the winter, with the low solar angle and flat panels, that's just enough solar power to fully charge the batteries by about 3:00 PM. If I were to tilt the panels, I could probably get away with 600 watts, but I'd still need the extra battery capacity. In the summer, when the sun is overhead, I'm fully charged by noon.
It's interesting to see your math. Would love a massive fridge like that but furnace sits under ours so if we ever did go with a residential would be much smaller.

First week of May installing five 160 watt panels (all that will fit) on tilt mounts with Tristar MPPT controller. Still running the Norcold so elected to not add batteries at this time, currently have 480AH capacity. Anxious to see how the system works out.

(Spoke to a solar installer who said they'd installed as much as 2000 watts on a motorhome!)
Scott
2005 Newmar Dutch Star 3810, Spartan, Cat C7 350 "OURVEE"
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Sun2Retire

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Re: Dry camping with residential refrigerator
« Reply #11 on: April 16, 2016, 07:28:10 AM »
What would be the most cost effective way to equip our RV to boondocks for at least 48 hours. I'm less concerned about air conditioning or microwave, btw, than keeping the refrigerator running.
To directly answer your question, after doing a load check as Lou suggested, one of the small, quiet inverter generators is probably your cheapest, most reliable route, and by far the easiest.
Scott
2005 Newmar Dutch Star 3810, Spartan, Cat C7 350 "OURVEE"
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2002 Dodge RAM 1500 Quad Cab "RTOAD"
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Gary RV_Wizard

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Re: Dry camping with residential refrigerator
« Reply #12 on: April 16, 2016, 08:15:03 AM »
Quote
My batteries are rated at 80 am hours. And the fridge is 15 amps. With two batteries that's 160 amp hours, so they should be able to run the refrigerator for abou 10 hours, is that correct? But that just means when the compressor is working right? And I read somewhere that you shouldn't allow deep cycle batteries to go below 50%, so really, together they are good for about 5 hours of steady usage?

Let's start over again on the battery math. You have about 160 AH potentially available, but for maximum battery life really only want to use 40-50% of that before re-charging. So yeah, figure 80 AH as the normal and 100 AH in a pinch.  Those are amps measured at 12v. Your inverter increases the voltage to 120v and changes to alternating current, but the math of  doing that means it draws at least 10x the amperage need ed on the output side. That means it pulls at least 10A from the batteries to produce 1A @ 120vac.

Your fridge requires a 15A capacity circuit, but it doesn't actually USE 15A, even when the compressor is running. Whirlpool puts a sticker on the interior sidewall that has model/serial etc. and the running amps should be shown there. The 18 cf Whirlpool Gold in our stick house shows 7.1 amps when running, and that includes the ice maker. Most of the time it's more like 3A.

The thing we cannot predict is how many hours the compressor actually runs. That is driven largely by the ambient temperature in the RV, how often the door gets opened and for how long.  If it is 10 minutes/hour average over 24 hours, then it runs 4 hours/day x 3A and thus about 12 amp-hours @ 120v. Since there is a 10x difference, that would mean your two batteries are exhausted after about 20 hours (100AH/120AH = 20). Assuming no other 12v usage, e.g. lighting.  With some reasonable care about opening the door often, my guess is that you can get through 24 hours well enough, but will need 3-4 hours of battery charging the next day.  You don't need a large generator for charging, though. The charging system in the RV won't draw more than about 10A @ 120v (1200 watts), so a 1800-2000W generator will be plenty to charge and also run some appliances. Not the a/c, though. Yamaha has a 2400W inverter-generator that is a handy size for Rvers and might even be able to start and run one a/c unit when nothing else is using power.
Gary
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Kevin Means

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Re: Dry camping with residential refrigerator
« Reply #13 on: April 16, 2016, 12:52:37 PM »
It's interesting to see your math. Would love a massive fridge like that but furnace sits under ours so if we ever did go with a residential would be much smaller.
I agree. It's nice having a residential fridge, but if I had had the opportunity to spec the motorhome out ahead of time, I'd have opted for a smaller fridge - something in the 14 to 18 CF range. Our fridge and inverter are easily the biggest consumers of all the "always on" devices in our motorhome, and the fridge is never filled to capacity - far from it. When boondocking, we don't like listening to our generator droning away for hours each day - even though it's surprisingly quiet for its size, with decent fuel consumption. A smaller res-fridge might only reduce the power draw by a couple amps each hour, but it adds up over 24 hours.

Kev
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ or an Acura MDX
RVI Brake 2, Minder TM-66 TPMS, 970 watts of solar
(Can't wait to spend more time RVing)
Lakeside, California

Becks

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Re: Dry camping with residential refrigerator
« Reply #14 on: April 16, 2016, 01:38:12 PM »
As stated the best answer is ...it depends... on a lot of factors. Like Kevin, we have res fridge, 2800 watt inverter, and use a lot of power. That said, we do have 1040 watts of solar and with good sun do not need to run genny much.
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Sun2Retire

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Re: Dry camping with residential refrigerator
« Reply #15 on: April 16, 2016, 05:21:27 PM »
the fridge is never filled to capacity
Really? I'm usually ready for the zombie apocalypse. Been reading about Gary's install, wondering if I could adapt it to a Sub Zero  ::)
Scott
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Gary RV_Wizard

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Re: Dry camping with residential refrigerator
« Reply #16 on: April 16, 2016, 06:05:52 PM »
Just add more batteries!
Gary
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OnSabbatical

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Re: Dry camping with residential refrigerator
« Reply #17 on: April 17, 2016, 11:00:27 AM »

Your fridge requires a 15A capacity circuit, but it doesn't actually USE 15A, even when the compressor is running. Whirlpool puts a sticker on the interior sidewall that has model/serial etc. and the running amps should be shown there. The 18 cf Whirlpool Gold in our stick house shows 7.1 amps when running, and that includes the ice maker. Most of the time it's more like

....so a 1800-2000W generator will be plenty to charge and also run some appliances. Not the a/c, though. Yamaha has a 2400W inverter-generator that is a handy size for Rvers and might even be able to start and run one a/c unit when nothing else is using power.

Thanks that explains a lot. The sticker in my fridge says 6.5 amps, but the Whirlpool rep didn't know what that means.

I'm confused, though, about generators. Are they recharging the batteries or powering the appliances or both? What would happen if, say, I got a 2000w Yamaha, and it wasn't enough power? Would it short out or something? Would this be solved by turning off my RV inverter (which only powers the fridge) while charging? Or Does it mean I'd just have to run the generator and recharge the batteries more often?
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Gary RV_Wizard

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Re: Dry camping with residential refrigerator
« Reply #18 on: April 17, 2016, 01:22:54 PM »
The generator just makes 120v power. What it does depends on what you plug into the generator's power outlet. If you plug the whole RV in, than anything can run, but the genset circuit breaker will trip if too many amps are demanded. Just as it would on shore power if you plugged into a 15A or 20A outlet. Some people plug a car-type battery charger into the genset and just let it charge batteries. Others may have altered the wiring in their RV to provide selective power to certain appliances. You could, for example, have a extension cord tucked away that brings power only to the fridge, if that's the main concern.
Gary
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OnSabbatical

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Re: Dry camping with residential refrigerator
« Reply #19 on: April 17, 2016, 01:57:29 PM »
But if I plug the RV into a generator, it will recharge the batteries just like if I plug into shore power, am I right? I discovered my inverter is 1000 watts,btw, if that makes any difference. The inverter only affects the fridge.

I'm thinking now I might get one or a pair of Yamaha 2000s and then if we need we could use the a/c.

I'd also like to keep it on hand at home for power outages, which we get occasionally.
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Lou Schneider

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Re: Dry camping with residential refrigerator
« Reply #20 on: April 17, 2016, 05:02:25 PM »
Yes, in theory a 1000 watt generator can produce up to about 80 amps to charge your batteries through the converter.

In practice, the converter's efficiency and power factor will limit the charging capacity to about 50 amps or less ... If nothing else is on.

If you have other users turned on, they will reduce the power available to charge the batteries a like amount.

This isn't a concern with a 2000 watt or larger generator, but may be a factor with a 1000 watt generator.  If you exceed the generator's power rating it will either trip a circuit breaker or shut down.  My Honda 1000 required stopping the engine and then restarting to recover from an overload.

Gary RV_Wizard

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Re: Dry camping with residential refrigerator
« Reply #21 on: April 18, 2016, 10:50:30 AM »
Your inverter for the fridge may or may not also be the charging system. I suspect not, and you probably have a separate converter/charger and maybe a 55A charge capacity. That means an actual charge rate well under than for most of the time, but maybe a peak of around 40A when you first start up the genset and plug the RV in. That's 40A@ about 14vdc, do maybe drawing 5A-6A from the genset (600-720 watts).

A 2000W genset may not be able to start the a/c unit without tripping its breaker. The compressor start-up amps will briefly exceed 25A and the gensets own breaker may trip before the load settles down to the running amperage (11-12 amps@ 120v). The 2400 (2000 continuous) or 3000 (2800 continuous) is a better choice. Be careful of the genset ratings - many models advertise their peak load capability, not the sustained or continuous load amount. The 2000W Yamaha inverter/gen has a 1600 watt output, close to what the a/c uses continuously (about 1440 watts).
Gary
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Gary Brinck
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OnSabbatical

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Re: Dry camping with residential refrigerator
« Reply #22 on: May 10, 2016, 02:54:13 PM »
Well, I took the plunge and got a Honda 2000 and left my two 12v deep cell batteries as is.

We've used the generator twice so far and it managed to run the refrigerator and some appliances without much problem, though it runs through the gas pretty quickly. I got about two hours on a gallon.

An RV salesmen who sells my model says I should keep the inverter on when I run the generator, presumably to keep it from overloading the generator, since the inverter is only 1000 watts. Does this make sense? The inverter is only for the fridge. I haven't tried running it yet without keeping the inverter turned on.
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Lou Schneider

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Re: Dry camping with residential refrigerator
« Reply #23 on: May 10, 2016, 05:43:13 PM »
That gas consumption is way out of line for a Honda 2000i. It shouldn't use more than 1/3 gallon per hour when running flat out under it's maximum load - that's 3 hours per gallon.  Under lighter loads with the eco-throttle on (so the engine doesn't run full speed all the time) you should get up to 8 hours per gallon.

Are you turning the choke all the way off once the engine is running?  If so, I'd take it back and let the dealer figure out what's causing it to use so much fuel.

The only reason to run the refrigerator via the inverter is if it's starting surge causes problems to the generator.  The downside is the current the inverter pulls out of the batteries has to be made up by the converter/charger, so it may take longer to charge the batteries.
« Last Edit: May 10, 2016, 05:46:42 PM by Lou Schneider »

John From Detroit

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Re: Dry camping with residential refrigerator
« Reply #24 on: May 10, 2016, 06:01:02 PM »
If the inverter is an "In-line" model, that is one that takes power in, charges the batteries, when power is available,  And which switches to INVERTER mode when shore/generator power is lost.. Leave it on and let it auto-switch.

120v--inverter---120v
. . . . . . . 12v . . . . . .

if it's a stand alone (12v---inverter---120v)

Then turn it off

(I hope that top one came out right, then 12v is supposed to be directly under INVERTER.)
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