Author Topic: Run Fridge off Starter Batts?  (Read 19353 times)

Offline Lin

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Re: Run Fridge off Starter Batts?
« Reply #60 on: January 27, 2010, 10:08:16 PM »
Clifford,

If the cooktop requires 110 volts, would it work off the 12 volt using one of those cheap, little, cigarette lighter inverters (hard wired, of course)?
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Offline Sean

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Re: Run Fridge off Starter Batts?
« Reply #61 on: January 27, 2010, 10:17:25 PM »
Update:

I did not realize it earlier, but my NFPA web site subscription actually allowed me to have a look at the 2008 code (in a really crappy read-only interface where you can't search, copy, or print anything).

I hunted around in there, and what I found is that the code was updated to specify the location of shut-off solenoids, but does not mandate them:

5.2.11.1 Vehicles shall be permitted to be equipped with a remotely controlled, normally closed, electrically operated shutoff valve installed within 9" of the outlet of the tank shutoff valve ...

The wording of the detector requirement is unchanged from my copy.

So, apparently, there is not yet a mandatory requirement for automatic shutoff based on LP detection alarms (but I would not be surprised to see it in the 2011 edition).  Therefore, your RV-shop friend was correct, I was, it seems, blowing smoke.  Mea culpa.

That said, the detector requirement is very real, and the price difference between detectors with and without the solenoid feature appears to be around $20.  That's what we used in our system here on Odyssey, and, as I wrote earlier, even my cheap-o Fleetwood had one 15 years ago.  I could not imagine wanting to have LP appliances indoors, such as cooktops, ovens, or refrigerators, without this simple and inexpensive safety device.

-Sean
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Offline Nellie Wilson

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Re: Run Fridge off Starter Batts?
« Reply #62 on: January 28, 2010, 01:49:51 AM »
Christy: Love the way your mind works! :)

Quote
From Christy: The big problem you will experience... is that your beer may be a bit warmer in the morning.   I usually deal with this situation by keeping the beer in the coldest part of the fridge, and if necessary, throwing a couple on top of the partially defrosted freezer goods until the fridge cools back down.

Quote
From Sean: I was, it seems, blowing smoke.

Sean: Blowing smoke or not, that automatic cut-off thingy seems $$$ well spent. Whenever I get LP hooked up, that little item will be in place. Just the peace of mind is worth it. Thanks for the tip.

Gus: Thanks bud! I'm sealing the compartment now, and will install a (removable) baffle to force air through those coils (per Christy's suggestion). Question: Is it okay for the air to flow over the condenser as well? Or should I steer it away from that?

If you get a minute, hop over that LP Flame-out thread? I describe that wire - my 'wire to nowhere' - in more detail. I'd value your input.

Nellie
 
Had to change a tire... >:(  got to put it on backward... :-\  still trying to fix it on photoshop... ??? ::) ???

Offline kyle4501

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Re: Run Fridge off Starter Batts?
« Reply #63 on: January 28, 2010, 05:36:58 AM »
If the flame goes out the gas will stop.  Same is true of your gas water heater and oven.  Stove tops though must be manually turned off.  It is a pretty basic function of all but the simplest gas devices like a blow torch or bottle top Mr Heater.

That may be true if everything else is working properly, if the safety valve malfunctions, the gas could still flow.

There are numerous other places that can allow gas to escape, hence the reason for good ventilation & gas detection.
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Offline rv_safetyman

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Re: Run Fridge off Starter Batts?
« Reply #64 on: January 28, 2010, 06:01:52 AM »
Sean, I was going to post that I was pretty sure that the gas solenoid valve was not required. then I saw your latest post.

When I install my fire suppression system, I always try to talk the owner into that kind of system.  Then I can wire the solenoid valve into my system so that I can shut off the propane if a fire is detected. 

I would say that perhaps 50-60% of the coaches made in the last 3 years have the valve, but many do not (not a very scientific survey).  There does not seem to be any logic as to what coaches have them.  I have seen the valve on medium level coaches and some top end coaches do not have them.

When I did a system without the valve I would install a CCI 7719 system.  Unfortunately they are out of business.  I have done a bit of searching and I can't find a detector that is equipped to operate a solenoid valve.  I have wonder if the new coaches have a vendor for that type of system?

Jim
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cody

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Re: Run Fridge off Starter Batts?
« Reply #65 on: January 28, 2010, 06:07:16 AM »
Sean, what puzzled me is that the automatic shutdown system is offered as an option on many coaches, it seemed to me that if it were mandated then the option would be a moot issue.  Like I said I can se the merit in having the system tho. Blowing smoke is ok too, I smoked up until 11PM july 10th 2008, thats when I had my heart attack. Just as a sideways note, my 1978 Revcon has the automatic shutdown system built onto the end of the built in LP tank, so those systems have been around for a while.

cody

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Re: Run Fridge off Starter Batts?
« Reply #66 on: January 28, 2010, 06:14:58 AM »
JIm, I can check and see about the availability of the soliniod, the rv shop guy I was talking about is don from marathon, he's their design engineer, it's a little early to call him tho, I get better answers if I don't call him in what is concidered the middle of the night on the west coast lol.

Offline Sean

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Re: Run Fridge off Starter Batts?
« Reply #67 on: January 28, 2010, 07:22:04 AM »
When I did a system without the valve I would install a CCI 7719 system.  Unfortunately they are out of business.  I have done a bit of searching and I can't find a detector that is equipped to operate a solenoid valve.

Jim, the Safe-T-Alert model 70 from MTI Industries has a solenoid contact:
http://www.mtiindustries.com/re6.htm

That's their top of the line; it does not look like any of their simpler units has the contacts as yet.

Now that most of the old CCI product is out of the distribution pipeline, I would expect to see someone step in to fill the giant void.  Possibly MTI, who have already recognized the opportunity, to the point that many of their LP detectors fit CCI cutouts (not the 70, unfortunately).

-Sean
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Offline rv_safetyman

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Re: Run Fridge off Starter Batts?
« Reply #68 on: January 28, 2010, 08:34:54 AM »
Hi Sean.  Thanks for the link to SAFE-T-Alert site.  I have been there several times looking for a total system.  I missed the fact that their model 70 has a relay that can control a solenoid valve. 

I did not see that they sell or recommend a specific solenoid valve.  That creates a problem for me, as I can't be in a position to select a valve and then be responsible for the selection.  I can get the valves that CCI used, but they are 9V solenoids and since they are continuously on, I don't think applying 12 V would be a good idea.

Jim
Jim Shepherd
Evergreen, CO
’85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
Somewhere between a tin tent and a finished product
Bus Project details: http://beltguy.com/Bus_Project/busproject.htm
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Offline Sean

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Re: Run Fridge off Starter Batts?
« Reply #69 on: January 28, 2010, 08:52:23 AM »
Jim, you might call MTI to see if they have a recommendation.  Alternatively, go down to your local RV dealer and poke around their showroom to find out what the big names are using.  Another option is to spec one of the valves that Atwood, Dometic, etc. use internal to their appliances, although you'd need to make sure it had a large enough orifice to be a full-system solution.

As long as you pick a valve that is UL listed for the application, I think you'd be OK.  But I understand completely why you don't want to be the "engineer of record" for such a system.

-Sean
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Offline gus

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Re: Run Fridge off Starter Batts?
« Reply #70 on: January 28, 2010, 03:55:03 PM »
Nellie,

I'm not sure your frig has a condenser? I haven't looked at the installation instructions since I corrected mine. I guess you could consider the return coils as a condenser but it is a different process altogether than a home freon system.

I understood that your frige is new so if you construct the baffle according to the installation instructions you will be ok. Understand that the instructions also describe installing without a roof vent (Which they don't recommend) and, as I remember, it is easy to get the two different installations confused. Mine came installed in the bus with no exhaust vent of any kind!!

Also, as someone else posted earlier, be sure to completely seal all around the top of the frige to keep the exhaust gases from coming out there. This will also keep cold air from outside out of the bus since the cooling air intake is directly from outside.

If you have no installation instructions I'll check mine tomorrow.

I posted to the other string before I saw this one so I hope I covered your question.
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Offline Nellie Wilson

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Re: Run Fridge off Starter Batts?
« Reply #71 on: January 30, 2010, 01:06:41 AM »
Thanks Gus!

My diagram calls it a 'condenser,' but I call it "a thing on the back, near the top, that sticks out and looks like a little radiator."

No roof vent? No exhaust vent at all? Much as I'd love that, I'd be too scared to try it. As for installation instructions, mine say almost nothing. Just one line of text that says, basically, 'allow at least 8" of clearance between the coils and the facing wall.' Not much help.

Anyway, I'm going with a 4" (flapper cap) exhaust out the roof, and two 2" holes in the floor. I've sealed the interior 'fixed wall' and sealed above the fridge (which I may eventually insulate?) And I added some insulation to the fridge sidewalls. The tricky part is the service access wall; it's got to be easily removable but (somehow?) sealed. Still working on that.

(Since I opted NOT to cut into my stainless, I need the removable wall to service the fridge. I'm may also keep a dedicated fridge battery in there, with external charging terminals.)

But it's all subject to change (Lord, isn't everything?) depending on what happens when I install propane. I'll have that done by a pro - or at least someone smarter than me - and they can tell me if I need to modify my (almost) existing installation.

Thanks again,

Nellie
Had to change a tire... >:(  got to put it on backward... :-\  still trying to fix it on photoshop... ??? ::) ???

Offline gus

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Re: Run Fridge off Starter Batts?
« Reply #72 on: January 30, 2010, 01:55:02 PM »
Nellie,

If the diagram says it is a condenser then it is, I couldn't remember for sure since it has been a couple of years since I installed my baffle. 8" is also correct if it says that. As I remember mine is much less, but mine is probably ten years old.

I also cut a hole in my roof after I discovered that it was required, but it came with no exhaust at all!! I had never owned an RV before this so I was completely ignorant of the need for an exhaust vent. I guess the only thing that saved us was that our 4104 leaked air like crazy!! Needless to say I went into shock when I finally read the installation manual. I installed a regular RV roof vent which is considerably larger that a 4" pipe.

I really don't blame you for not wanting to cut a hole in the side but mine was already there. It does make for easy servicing though, I once had to replace the circuit board and it was relatively easy. I recommend that you just make the frig easy to slide out from the wall for service, it won't have to come out very far for most service. They are not very heavy. The LP line can be installed with a couple of big loops in a copper line or you can use a flexible hose for part of the line.

Both sides of my frig are covered by 3/4" plywood which also double as a closet wall and a bunk bed wall. I slide the bunk beds out of the way and remove that wall with only four screws.

It seems to me that two 2" intake holes and one 4" exhaust hole won't provide enough air, but, if the directions say so, it is so! My frig is 6 cu ft. If yours is smaller then 4" may be enough.

I don't recommend a separate frig battery. Batteries spill acid and give off fumes when being charged, you really don't want that inside the bus. You surely can find a DC wire somewhere near the frige and eliminate worrying about another battery.  The wires to the old passenger reading lights are pretty heavy because there were so many lights.

My LP setup is two 20lb bottles like on BBQ grills. They are mounted on a two bottle holder like on RV trailer hitches. The big advantage to this setup is that you can remove the bottles and carry them to be refilled and you always have a spare. My original tank was permanently installed and it was a real pain to find a refill station I could get into. It was a monster and only held 10 gal!! Two 20lb tanks take much less space and hold the same amount. (Pounds/gallons are confusing, but the tanks are listed in pound size and when you get them filled it is in gallons!! One 20lb tank/bottle holds appx 5 gal). I also have two more 20lb tanks in another compartment for my heater, which I don't use very much. These provide plenty of LP backup.

20 lb tanks can be purchased at Home Depot for around $28. The tanks you see outside stores in wire cages for exchange are only about 18 gal although they are almost as large in physical size. They can be used as well but you are better off owning your tanks and getting them refilled, much cheaper in the long run.

Sorry, didn't mean for this to get so long!
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Offline gus

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Re: Run Fridge off Starter Batts?
« Reply #73 on: January 30, 2010, 03:16:01 PM »
 Nellie,

I had to go out into the snow anyway so went by the bus and got my manual.

It shows that the rear clearance between the condenser (Yes, it has a condenser!) at the top and the larger coils at the bottom should be no more than 1".

If the clearance is more than this (you said yours is 8") you need two small horizontal baffles the full width of the rear opening which come to no less than 1" each coil.

These force the rising air to flow through these two coils.

In the vent diagram these baffles are very small from the edge so they are easy to miss. You don't need a large vertical baffle unless the frige is more than 24" from the bus wall.

Again, these are the instructions for my Norcold Model 683. Yours may be different, but look carefully at the side view vent diagram in your instructions and you may see them. They are identified as number 5 in my diagram.
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Offline Nellie Wilson

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Re: Run Fridge off Starter Batts?
« Reply #74 on: January 30, 2010, 04:26:57 PM »
Gus -

Okay, point taken... I went with a bigger hole at the bottom, but am stuck with the 4" chimney (already bought the pieces). BUT (taking your advice) ran my holding tank vent separately (so it takes no air space). Also, my A/C vents into the fridge 'chimney,' directly below the coils. The A/C exhaust acts as a fan to increase air circulation when the fridge needs it most... when it's hot.

Hard to visualize, I know. I'm gonna try to post a couple photos to give you the picture. :) Let me know your thoughts?  I'm kinda sawing... reading posts... sawing... reading posts... plugging hole... reading posts...

Just learned I can only post one pic per post(?)... so I'll make another couple of posts. Sorry for the inconvenience.

Nellie

If the (eventual) propane installer says 'change it,' no problem - I'm cutting the holes within the perimeter of a (potentially) larger vent. 
Had to change a tire... >:(  got to put it on backward... :-\  still trying to fix it on photoshop... ??? ::) ???