| [GMCnet] Refrigerator Advice [message #311991] |
Tue, 10 January 2017 16:51  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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Senior Member |
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It is very hard to get enough battery power into one of our coaches to make household refrigerators work well unless you are nearly always plugged into shore power or willing to run your generator or the engine when not. Note that even the largest 45 foot rolling condos with six or even eight 8D batteries with over 1000 amp hours can only dry camp for a day or at most two before needing to run the generator. To prove this for yourself, get a Watt meter like a Killawatt unit and plug your home refrigerator into it. Use the refer normally for a few days and then read the number of KW consumed. Convert that into average watts per hour at 120vac. Know that even the most expensive inverters are not 100% efficient so when you convert that into amps per hour at 12vdc know that you will need to increase that draw assumption to make up for the less than 100% efficient conversion from 12vdc in the batteries to 120vac needed by the refer. The numbers will scare you when you consider that about the most battery capacity you can cram into a GMC is four 6v golf cart batteries (around 400 to 450 amp hours of capacity with around 200 to 225 amp hours available. If you have to run the furnace while also servicing the inverter power needed to run your home style refer your run time will drop much more quickly as the furnace alone will consume 7 to 9 amps per hour of operation.
A more complete explanation of all this is contained in a presentation I made to GMCMI a couple of years ago that you can download from the GMCMI.org web site: http://www.gmcmi.com/wp-content/uploads/2013/02/GMC_Battery_Presentation_-_Jerry_Work.pdf
Bottom line, at least for me, is you cannot beat propane for space heating, water heating and running the refer while dry camping in a GMC. In another presentation made at the GMCWS rally in Coos Bay, OR, in October of this year I also talked about running our Onan generators on propane, as well: http://www.gmcmi.com/wp-content/uploads/2016/10/Feeding-the-Barbarian-Jerry-Work.pdf Once you make that switch you will never look back at things like home refers and massive battery banks because your Onan will start easily, run quieter and more smoothly, outlast you and the next several owners and have no more ugly exhaust smell so you can run it easily and as often as you need to to keep everything in your GMC running comfortably whether plugged into shore power or not.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
glwork@mac.com
http://jerrywork.com
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Message: 12
Date: Tue, 10 Jan 2017 14:33:59 -0700
From: Jon Roche
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Refrigerator Advice
Message-ID:
Content-Type: text/plain; charset="utf-8"
Others may chime in on the actual math, but the batteries charge rate will vary. I think it takes longer then 2 hours to charge up a house bank
drained down 75%. the batteries will not take the full 45 amps.
i can only say my experience. with my original 12v marine battery, the fridge seemed to kill the battery in a 24 hour period or less. I then
upgraded to 2ea 6v golf cart batteries, about 215 amp hour, and it would last 36-48 hours. I added 65 watt solar, and it did not really add any
time, batteries were drained dead by sunday morning when I had rolled into camp friday night. I then stated putting Ice in the fridge, and it
seemed to help getting me through Sunday.
with my 2 golf cart batteies drained all the way down, a 2 hour drive home(alternator charge), they were charged up quite a bit, but never topped
off 100%.
remember when the sun hits the coach, and you are not running A/C, it can get really hot. Also the back of the coach fridge is usually exposed to
outside temps. (obviously not the case if you install a residential unit, you will probably close off the back of the fridge compartment).
there are people who run electric fridges and are plenty happy with them. My experience though, is if you ever want to make it longer then 2-3 days
without a power cord, then a propane fridge is the way to go.
--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] Refrigerator Advice [message #341389 is a reply to message #311991] |
Fri, 01 March 2019 09:30  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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A whole part of this discussion that seems to have been omitted is the bottom right corner of the spreadsheet titled
"GMC Annual Operating Expenses".
We have a very original '73 23'. We really like to travel. We often dry camp over night, and do some longer dry camp in special places and rarely boondock more that a couple of days.
When the original Nocold 3.4CuFt reefer went bad, we needed a work around fast. That was a single door (so was the Nocold) dorm reefer with minimal freezer and not much to offer. We powered that with a Hazard Fright 750 continues Modified Square Wave inverter from our house bank of 2ea GC2s. It was adequate for the rest of that season and the next. Mary did not like it at all.
Hey, if the cook does not like the galley, then something better change. We went little reefer shopping for the second time in two years and the offering was much improved. The new 3.5CuFt Frigidaire (Chinese) has a separate freezer door and much better internal arrangement. Running, it draws a little more than 4 amps DC. This unit is also about 8" shorter than the Nocold. So I built a drawer to go under it.
Still powered by the same (actually, this is a replacement as the smoke leaked out of the first) MSqW inverter. I actually carry a spare. They are small light and cheap. It has the added benefit that we now have 120V AC available all the time. The inverter says it is good for 1500watts (VA?) peak, so there is always AC power left over.
When you open the door and the light comes on, that is when you hear the fan in the inverter spool up. Replacing that with LED is on the work list.
And some of you are asking how long I can run on the house bank with this drain?
Good Question.
According to the Trimeteric, that is about a day and an half. If we get on station at dinner time of day one, then, after dinner of day two I better plan on firing the Onan for a couple of hours. With a PD9260 next to the house bank, I can recover the house bank to 90% in less than 3 hours. If it is someplace with a quiet time, that works out great.
All of this for (not including the custom hand crafted drawer unit) was less than 200$us - cash out of pocket. That includes the cost of the drawer, but not the upgrade to the converter/charger. We sold off the unloved reefer at a slight loss.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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