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Author Topic: Run Fridge off Starter Batts?  (Read 8851 times)
Nellie Wilson
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« on: January 25, 2010, 03:21:18 AM »

A minor victory: I finally sent my trusty ice chest to the luggage bay! Yep, my former 'pantry' - a 3-way Norcold fridge - is now making ice and chilling food (well, in my case, a couple sticks of butter). I'm so excited I woke at 4:00 AM just to check. l'm sitting here in awe, watching her (silently) working away.

Trouble is, I have only a 'one-way' power source: AC. No propane, no gen set, no house batts. So once I'm unplugged, no fridge. Unless... unless... I run it off my engine (starter) batteries? Only while running, you understand, just until the next power post.

I have a Vanner Equalizer but - like most things on my bus - it's not hooked up.

So, my question(s): 1) Can I tap a 12v supply off the Vanner? 2) How does it hook to the engine batts, and 3) how can I check it before wiring it to my (beautiful) fridge (so I don't ruin the fridge)?

Thanks for any help,

Nellie (the hostess with the mostest)
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luvrbus
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« Reply #1 on: January 25, 2010, 04:09:20 AM »

Nellie, you really need to connect the fridge to propane they are not efficient on 12v and it will draw a lot of amps and your 2 sticks of butter will be a liquid.
A 20 lb propane bottle will run the fridge for 3 or 4 weeks.

good luck
« Last Edit: January 25, 2010, 04:14:37 AM by luvrbus » Logged

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bevans6
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« Reply #2 on: January 25, 2010, 04:22:58 AM »

Running the fridge from the start batteries via the Vanner is a good solution for while the engine is running, and the fridge is already cold.  The 12 volt draws a fairly heavy load, and needs to be wired with 10 gauge wire, but it won't cool the fridge down by itself.  Propane requires a full installation of the venting system, which you can get away without if you run the fridge on electricity, and it's perfectly acceptable to run the fridge on propane while travelling.  I find that the propane usage is quite low, I actually get a couple of months from one 20 lb tank.

Brian
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« Reply #3 on: January 25, 2010, 04:34:16 AM »

your right Brian the side by side will run about 3 or 4 weeks on 20 lbs

good luck
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Jerry32
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« Reply #4 on: January 25, 2010, 06:45:18 AM »

 I just have a houshold type fridge and it runs off the inverter just fine. I have solar panels that charge the batteries so that helps too. my batteries will run the fridge and the heat all night so no problem there.  I didn't want an RV type fridge for the  reason of the vent needed.   Jerry
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« Reply #5 on: January 25, 2010, 07:28:01 AM »

I think I am going to do a cost/benefit analysis of the propane RV type fridge vs house type fridge.  Cost of install, cost of ancillary equipment, length of time off the grid, impact on boondocking, payback timeframe, cost per day of usage.  It would be interesting to find out what's what.  I'll have to price out generator run time, batteries, inverters, refers of both types, propane run time cost, etc.  Could annoy me for quite a while   Wink

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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Ed Hackenbruch
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« Reply #6 on: January 25, 2010, 07:32:50 AM »

Getting to be a long winter up there Brian? Grin
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« Reply #7 on: January 25, 2010, 07:48:08 AM »

I took a house type out of mine to much generator time to keep the batteries up.
You could tell every bus at Quartzsite that had a house type the generators were running. 



good luck
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Ed Hackenbruch
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« Reply #8 on: January 25, 2010, 07:53:08 AM »

The guy next to us ran his generator 12-14 hours each day. I would think that gets a little spendy after a while.
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« Reply #9 on: January 25, 2010, 07:56:00 AM »

Clifford,
I was running my generator mostly for heat I don't have a furnace installed yet. and the weather was cold enough to keep my food cold lol!

John
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« Reply #10 on: January 25, 2010, 07:57:37 AM »

I just don't get the aversion to RV type fridges.  Ours runs quietly and cold on propane whenever we are unplugged.  I don't know how much propane it uses but we sure don't notice the consumption and we have to keep it turned to the 2nd from warmest setting or it will freeze things in the fridge compartment.  
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« Reply #11 on: January 25, 2010, 08:14:31 AM »

I think the aversion to RV type fridges comes from several places.  I personally have one, and I hate getting up in the middle of the night to clear a no flame error code, and I can't rely on it to run without that happening on propane.  Judging from the number of hits you get on google, "No FL" is a pretty common problem.  So there's that.  A lot of people don't want to cut the wall of the bus for the vent/service access portal, and they don't want to put a big vent cap on the roof.  My bus has the roof vent, but no side vent.  It has a vent hole cut into the floor and into a luggage bay.  I'm not very happy with that, for a number of reasons, but it works fine and vents well, so I have yet to take a sawzall to the bus wall.  It does mean that when I have to service it I have to remove the fridge from it's built-in hole inside the bus interior, disconnect the propane, take off all the trim, and physically move it into the hall way.  Major PITA, and I did it three times last summer.  The upfront cost of the fridge is high, they are pretty proud of them - $1400 for a 8 cu ft model like mine.  And you have the whole propane thing.  You have to build a propane cupboard to store the propane bottles, vent it high and low, run the lines, install detectors, worry about the whole fire issue, get propane inspections for your insurance company, while electric is so clean and not-nasty, and familiar.

Just some thoughts.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
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1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
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« Reply #12 on: January 25, 2010, 08:46:36 AM »

I vented mine to the outside bottom of the bus I have no side vents that won't happen on my bus.
It been installed 3 years now and I never had to remove it yet. 
If you keep getting that code I would check the ground I had that problem till I grounded it to the frame


good luck
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« Reply #13 on: January 25, 2010, 09:32:22 AM »

doubling up the ground is a good idea.  Currently it would be grounded by the DC feed line, which is about a 20 ft long 10 ga wire, and I suppose the AC line if that is plugged in.  Who know, maybe it only faults out if the AC line is unplugged.  I never run it on AC, and I sometimes leave it unplugged so that I can plug in my battery charges, and I forget to plug it in again.  I can't think of a reason not to run a separate ground strap.  It sits in a wood cupboard, so it doesn't actually touch the bus chassis anywhere.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
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Sean
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« Reply #14 on: January 25, 2010, 10:01:15 AM »

Trouble is, I have only a 'one-way' power source: AC. No propane, no gen set, no house batts. So once I'm unplugged, no fridge. Unless... unless... I run it off my engine (starter) batteries? Only while running, you understand, just until the next power post.


Nellie, please straighten us out:

Is this an absorption type fridge, meaning the kind that normally runs on propane, and you simply do not have propane hooked up?  Or is it a compressor type fridge?

I ask because Norcold (or as some like to call them, Ne'erCold) makes both types.  The absorption style is common on RV's; the compressor style is common on boats.  Bus conversions might have either.

If you have the absorption style, then
Clifford is absolutely correct -- these are not efficient at all on electricity.  They are meant to be run on propane, and the electric inputs (which actually run heaters, with less output than the propane burner) are basically an afterthought, put there to take advantage of free (well, already paid for in your campground rate, anyway) 120-volt electric power when on shore, and/or to assuage fears that people have about running them on propane while under way.

In fact, if you intend to run mostly on AC power, with occasional inverter use while underway, then you will be much better served to sell the absorption fridge on eBay (despite their shortcomings, they are a specialty item and supply and demand keeps prices high) and run down to Wal-Mart and buy yourself a small household compressor type.  I've seen them for less than a c-note.  These small compressor fridges are much more efficient on electric power than absorption units.

If you already have a compressor style unit, then no problem just hooking it up to an inverter.  But one caution:  compressors really need true sine wave, not MSW.

HTH.

-Sean
http://OurOdyssey.BlogSpot.com

Addendum: Upon rereading the original message, I see that you have an absorption unit.  My advice to trade it for a small compressor style still stands.

If you are married to the absorption type because you plan to install propane later, my advice would be that it is probably better to just deal with the propane installation now, rather than fudge it to work off 12 volts on a 24-volt bus.

These things draw a huge amount of power on DC, and getting the Vanner install correct and properly fused will be critical.

If the concern is just a day's drive between power poles, try just filling the thing up.  Use water jugs to use up most of the unoccupied space in the fridge.  They will act as a thermal mass, keeping everything else cold while you drive.  Same goes for the freezer:  freeze some water or even Blue Ice packs in there.  Try not to open the doors until you are plugged in again.

-Sean

« Last Edit: January 25, 2010, 10:11:41 AM by Sean » Logged

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