Upgrading from 3-way fridge..

Kodachrome

Senior Member
Joined
Aug 10, 2009
Messages
377
Location
Colorado Rockies
Ok, so I am officially over trying to keep my food and film cool when on extended trips with this darn propane powered Dometic fridge, a 1.9 CU in my Bobcat. Life is good when I can find a level spot and don't have winds blowing out the pilot light, but other than that, it really sucks to be honest.

I am on the last day of a week long trip with my wife, we have been waaay off the grid camping on BLM land, some incredible places. But the weather has been rough, which is great for photos, but not for the fridge. It is howling wind outside right now and I have to go and make another cardboard partial vent cover, ugh!!!

So bottom line, I am just going to suck it up and add another 85 watt solar panel to the underside of the cabover to get us to at least 170 watts and then get an Engel SR 48 AC/DC fridge/freezer. That is what I think will fit the place the Dometic is now. They also make a 60 quart SR70 in AC/DC but I don't think it will fit.

Anyone else put an Engel fridge in the place of the 1.9 CU Dometic and if so, what size?

Typed from our iPad-2 somewhere in BLM land...
 
I went with a Waeco/Dometic CR65. It fit in the cabinet with only minor changes. The CR65 is AC/DC and I think that the AC is even a waste. It is quiet,uses very little energy and makes ice no problem. It has an interior light.
With a 125 watt solar panel and dual batteries, I can boondock forever. All of my lights are led also. I am very happy.
You won't be disappointed.

Jeff
 
That CR65 is spendy from what I can tell, $1,200+? also, it looks like it is a drawer style, not as easy to get into when top down camping. No interest in the MT45, I am looking for a front door type like the SR48 and SR70. I am hoping to get my solar possibly up to 200 watts since I only have one battery, not sure where I could store a second.

Thanks for the replies!
 
Kodachrome,

We feel your frustration and will be watching the replies as we are considering doing a similar swap. Our preference is also the front door Engel that would fit in the existing cabinet that holds the small 3-way Dometic. Our question is can we do it without a solar panel? We have duel AGM batteries in the camper. The only electricity we use is LED lights and the heater. No using laptops, watcing DVDs, playing music, charging phones, etc. We rarely if ever have gone more than two nights in one location so the batteries get recharged while driving. So is it possible to switch to an Engel or similar without adding solar?
 
Batteries are measured in AMPS, or more correctly amp/hours.

So, to size the battery you need to figure out how many amps you will be using in a 24 hour period, or between times of recharging the battery.

The fridge should be easy to find out, most them will give you a 24 hour usage or an hourly usage (which you can calculate up to a 24 hour period). Fridges usually are turned ON the entire 24 hours, other devices may not be.

Sometimes they also list the start up amps, as when going from off to a desired temp, say 34-35 degrees. This is usually a large amount of amps, however, if your food starts out being already cold when you load into the fridge, then amps can be reduced.

On a front door fridge, another small factor is how many times the door is opened or left open for long periods of time, as cold air sinks out the front of the fridge and needs to be replaced, so you'll need a few more amps. Having more cold mass (cold food) in the fridge will reduce amp usage, as the cold mass will help cool the fridge back down quickly (amps can be reduced). This is just an excerise in fine tuning.

- - - - - - - - -

If the manufacturers are not talking amps and instead use WATTS (not a term used in batteries), then the convesion is pretty simple to amps.

Amps = watts / volts

If they say 300 watts for a 24 hour period of time, then... 300 watts / 12 volts = 25 amps, which would be a little over 1 amp per hour in a 24 hour period.

- - - - - - - - -

If you have other 12 VDC devices, see if you can figure them out as well for the number of amps per hour, then multiple the number of hours of usage and sum everything up.

LED lights don't use much and they are usually not ON that long.

The heater does use some amps to run the fan and not much to do the auto ignition.

Figure out the amps, add them into the other things and you'll have the knowledge that you want to size your battery.

- - - - - - - - -

I personally don't like to take any battery below a 50% rating of it's stated amp/hour capacity.

So, if you've got 25 amps of usage between recharging the battery then a 50 amp/hour battery should be OK.
A higher amp/hour rating battery will give you some extra capacity. Maybe a 60 amp/hour or higher battery and I'd feel comfortable.

And, yes, most batteries are well above 12 volts when fully charged. However, figuering everything at 12 volts, should give a little extra wiggle room.

- - - - - - - - -

Using a properly sized solar panel with a quality charge controller will often allow your use of the 12 VDC devices during daylight hours without draining the battery. In fact the solar panel should have enough capacity to operate the 12 VDC devices and charge the battery at the same time. Thus your usage of the devices at night, when the solar panel is dead, is all you have to think about regarding the size of the battery. But, still, extra capacity in a battery is always good to have.

A lot of solar panels actually put out more then 12 volts, often up to 20 volts and are adjusted by the charge controller down to around a 14 volt charge to a battery that changes as the battery achieves full charge. However, to be conservative I always calculate using 12 volts to get my amps/hour charge to the battery. Doing this, will be an error on the safer side of things.

Solar panels are often rated in WATTS, so when thinking about what capacity to buy, do the conversion...
135 watt solar panel... 135 watts / 12 volts = 11.25 amps/hour.

However, solar panels are often not as efficient as stated for lots of various reasons. Amount of sunlight, angle of sun to panel, over enthuastic rating from the manufacturer, etc.

I usually discount the Watt rating of a solar panel to about 70% of the rating. So, the 11.2 amps/hour turns into 7.8 amps/hour.

Need 25 amps to charge up your battery? This one should do it a couple of hours, depending on what kind of charge controller you have and the battery charging profile of that unit.

7.8 amps per hour when the sun is shining should also be enough to operate the fridge I mentioned above with a little extra to charge the battery up at the same time.

Having a charge controller with a multi-function meter (remote or built in) will usually give you a lot more info on your 12 VDC devices than something that just has blinking lights.
 
That CR65 is spendy from what I can tell, $1,200+? also, it looks like it is a drawer style, not as easy to get into when top down camping. No interest in the MT45, I am looking for a front door type like the SR48 and SR70. I am hoping to get my solar possibly up to 200 watts since I only have one battery, not sure where I could store a second.

Thanks for the replies!

I found mine for $680.00. I have my door swing set up so I can access with out crawling into the camper.
http://www.smallspacesappliances.com/dometic17cuftfrontloadingrefrigeratorfreezer1224vdc110220ac-1-2.aspx

Jeff
 
A lot of solar panels actually put out more then 12 volts, often up to 20 volts and are adjusted by the charge controller down to around a 14 volt charge to a battery that changes as the battery achieves full charge. However, to be conservative I always calculate using 12 volts to get my amps/hour charge to the battery. Doing this, will be an error on the safer side of things.

Solar panels are often rated in WATTS, so when thinking about what capacity to buy, do the conversion...
135 watt solar panel... 135 watts / 12 volts = 11.25 amps/hour.

However, solar panels are often not as efficient as stated for lots of various reasons. Amount of sunlight, angle of sun to panel, over enthuastic rating from the manufacturer, etc.

I usually discount the Watt rating of a solar panel to about 70% of the rating. So, the 11.2 amps/hour turns into 7.8 amps/hour.


You sorta veered off track here. Lets assume the panel puts out 135watts at 20V like mentioned above, you don't take 135W / 12V * 70% efficiency to get 7.8amps. You're using the efficiency number to make a correction to a fundamental miscalculation. What is really happening is the panel is putting out 6.75amps at 20V, which equals 135watts. However unless you're using a MPPT charge controller when the 20V gets dropped down to your charge voltage (usually about 14V not relevant to the point) you still only have 6.75amps to work with. See the difference?
 
Okay, enough tech. Ancedotally, I can tell you, running everything as much as I can, in freezing conditions, my two sears platinums and one optima just laugh at such usage over a weekend.
 
Just got home, what a great week...now it is going to snow here at home, LOL!

Thanks for all the GREAT info, PM's. Might have the 3-way fridge already sold so I think we are going to move fast on this.

All in all, we LOVE our ATC Bobcat, the first mission it has had since the end of Kodachrome and it went great.

So in the name of keeping us in the field, professional and in single locations for up to 10 days, my wife thinks we should suck it up, spend the grand and get our rears back out there..
 

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... my wife thinks we should suck it up, spend the grand and get our rears back out there..



Does your wife have a single sister with that kind of attitude?
And, if she's about the same in a bikini... well...
I'm of course... just kidding, however, I've usually found that there is only one of them in any family of sisters, so, you've got a keeper.
Do whatever she says.
 
Okay, enough tech. Ancedotally, I can tell you, running everything as much as I can, in freezing conditions, my two sears platinums and one optima just laugh at such usage over a weekend.


My Customer, Ken, runs his MT45 for 3 days in the Bobcat on a single 75ah AGM no sweat.
 
Alright, so I am getting this together. In tems of solar, I have got a 20 pound 100 watt panel coming that will work great under the cabover on sliders, that will give me a total of 185 watts. But I am wondering a couple things:

1. I am using a Morningstar Sunsaver 10 charge controller, will I be better off with the 20 amp unit since the total between the two panels could go over 10 amps?

2. When wiring the panel, can I just splice into the existing leads from the current panel?
 
Trying to figure out if one of these Engel's will fit, moving forward with the Solar for sure but I need to be sure about the fridge too and in talking to Marty, he does not think either the SR48 or SR70 will fit:

Dometic 1.9 CU 3-way:

http://www.dometic.com/enus/Americas/USA/RV-Products/refrigerators/Refrigerator-Product-Display/?productdataid=71045

Engel SR48:

http://www.engel-usa.com/sr48_specs.html

Engel SR70:

http://www.engel-usa.com/sr70f_specs.html

Looks to me like the 48 should fit with an inch less in the width compared to the RM2193.

Thoughts?
 
Just got home, what a great week...now it is going to snow here at home, LOL!

Thanks for all the GREAT info, PM's. Might have the 3-way fridge already sold so I think we are going to move fast on this.


You do have me sold, well, as long as you keep posting those lush Kodachrome images. Drool. So let me know about the fridge. Keep it in the WTW family and all.

Snowing here too. Last couple of days. Could get by with a cooler ... to keep things from freezing.

More pics please.
 
When deciding don't for get how Physics works. Heat rises - Cold sinks. So, what happens as soon as you open the door of your front load?
 
Alright, so I am getting this together. In tems of solar, I have got a 20 pound 100 watt panel coming that will work great under the cabover on sliders, that will give me a total of 185 watts. But I am wondering a couple things:

1. I am using a Morningstar Sunsaver 10 charge controller, will I be better off with the 20 amp unit since the total between the two panels could go over 10 amps?

2. When wiring the panel, can I just splice into the existing leads from the current panel?


What is listed max output power voltage (and/or amps) of your two panels, depending on that you may or may not actually go over 10amps. If its up around 20V you'll only hit ~9amps, since a lot are around 17V you'd be in the 10-11amp range under "perfect conditions" which likely isn't going to happen too often. Morning start lists a 25% over charge margin which I think would likely protect you in the off case that happened here and there.

Worst case if it did eventually burn up you could then get the 20A one and would only be out the $40-50 for the 10A model.
 
When deciding don't for get how Physics works. Heat rises - Cold sinks. So, what happens as soon as you open the door of your front load?


What happens is the same thing that has always happened with my 3-way, you lose some cold air. I need the counter space so the front load system is still the best way for me to go with it at the moment, especially when developing film out in the field.
 
You do have me sold, well, as long as you keep posting those lush Kodachrome images. Drool. So let me know about the fridge. Keep it in the WTW family and all.

Snowing here too. Last couple of days. Could get by with a cooler ... to keep things from freezing.

More pics please.


Sarah and I are starting the long process of editing 1,285 rolls of film, then we get a book publisher and get this sucker out on the shelves. I do have more posts on my blog coming though, have to keep that alive.
 

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