DIY: How to make your own 12V Fridge

[terranaught]

msw inverters don't run compressors very well a sine wave will give better performance.
this is my solution to low power fridge https://bluebarrelgarden.weebly.com/low-power-chest-refrigerator.html it's kinda large for a van tho.

 

[Trebor English]

msw inverters don't run compressors very well a sine wave will give better performance.
this is my solution to low power fridge https://bluebarrelgarden.weebly.com/low-power-chest-refrigerator.html it's kinda large for a van tho.

The $25 ($20 open box) Harbor Freight 400/800 inverter I have is modified square wave.  How would you evaluate better performance?  

This is my solution to a low power and low cost fridge.  

https://vanlivingforum.com/showthread.php?tid=27624  

Interesting link.  I use water rather than olive oil because it melts at 32°F.  40°F seems a bit warm for keeping food.  Either substance keeps the fridge cold without lots of batteries.  

My Haier 1.7 cube fridge is also large for my mini van.  The Alpicool C15 and C20 are quite a bit smaller.

 

[terranaught]

the modified square wave dosen't run the compressor at full power, greatly reducing efficiency, ie has to run longer for the same cooling power

 

[wasanah2]

I don't get on here often these days, but wanted to stop in to update the thread.

I have one of these conversions that's going on two years of absolutely trouble-free operation, and another on about 18 months.  These have performed perfectly for us on the road, and continue to use an average of 30 Amp-hours per day or so!

I'm late to this thread, but I thought I'd share plans I have for a mini fridge and maybe you can tell me what you think.  I plan to use a very small mini fridge.  I'm going to use this fridge on shore power, but what I need to do is fit it inside a cabinet , make it have more room and convert it to a top loader.  BUT I don't want to turn the workings of the fridge.

This is what I plan:  This is a very tiny fridge, but it gets very cold.  I plan to remove the door and build with insulation a top loading 3 sided box that tightly fits the area where I removed the door, then a door in the top of the box will make it so the cold air will stay in and not sink to the floor every time it's opened.  Inside the cabinet, the fridge addition's lid will be  flush with the countertop.  That way, I lift the door from the top when getting into the fridge.  It will 1/ give me more fridge space.  2/ be more efficient as a top loader.  So instead of being this tiny box, it'll be a longer insulated box that uses the workings of it.

Before I do this, I'm wondering if you foresee any problems with this.   It will go in my 30' 1988 Nomad with updated electrics.  I know that it means I have to keep the countertop empty because it would be inconvenient to have to clean it off every time I need to get into it, but I'm willing to do that for the additional fridge space and the top loading design.

I thought of this when at an ice cream parlor.  They had a top loading freezer and flipped up the counter top to get the ice cream and flipped it back down to keep the heat from getting in.  Any thoughts on the idea before I destroy a perfectly good cabinet, counter and refrigerator?

 

[highdesertranger]

they make top loading refrigerator/freezers. even cheap ones. also have you taken into account air circulation around the condenser. highdesertranger

 

[wasanah2]

they make top loading refrigerator/freezers.  even cheap ones.  also have you taken into account air circulation around the condenser.  highdesertranger

There's an air vent to the outside of the RV right close to where I want to stick it.  I can actually give airspace all around it in the cabinet.  Where the original huge fridge used to be is now pantry storage and so I have the room available under the cabinet.  I thought I'd use what I have instead of buying a new fridge.  The thing is so dang cold.  I keep it on the lowest setting and it's really cold up near the freezer part.  The freezer part would only hold 1 ice tray if I used one.  It's small but it's what I have and it seems more powerful than it needs to be.  I could take advantage of that and get more use out of it. 

I haven't seen many top loading fridges.  Freezers, yes, but not fridges.  I also have a small freezer that is about the same size as the fridge.  I usually have that packed full, which is the efficient way to keep it. 

Would I need an additional fan inside the addition to distribute the air inside or would the fridge's fan be enough to keep things cold on the far side of the unit?

 

[John61CT]

First off, the front opening design does not in reality have significantly lower energy efficiency than top opening, it is the massive contents that buffers the cold, the air is unimportant.

That custom construction will be a great challenging project, but not IMO worth the effort.

Just save your pennies for a 12V compressor fridge, either drop-in unit designed for that purpose, or make a custom box and buy a fridge kit the right size, as is most common for boats.

Actually finding a portable unit the right size would work great, ideally one where you could add more insulation around most of it, and ventilate the hot areas.

Or just do a front-opening and free up the counter space.

 

[B and C]

"...make it have more room and convert it to a top loader.  BUT I don't want to turn the workings of the fridge."

A residential compressor on its' back will only work if you mount the compressor in its' original orientation.
Get a 12v top loader freezer/fridge if you think the very minor savings of a top loader vs a front loader is worth butchering you countertop.

 

[wasanah2]

A residential compressor on its' back will only work if you mount the compressor in its' original orientation.
Get a 12v top loader freezer/fridge if you think the very minor savings of a top loader vs a front loader is worth butchering you countertop.

The countertop is getting redone anyway.  I actually like the idea of a top loader and the cold doesn't fall out when you open the door.  But maybe this is more complicated than I thought.  See the fridge is a house current dorm fridge, not a 12 volt.  It was cheap.  I just have it plugged in to the wall and that's running to my electrical system/converter.  This camper is pretty old (1988) so I had the electric updated when it was remodeled.

 

[terranaught]

I salvaged a water cooler unit that has a 1.5l tank the evaporator is wrapped around, I thought I could use it as an ice reservoir type fridge, but it is ungainly, and is low on the priority list, instead of a thermostat I was thinking of a photo detector to determine ice by diffused light.

 

[John61CT]

There is a big difference between experimental Science Projects and asking for practical advice

 

[bullfrog !]

I believe you will find usually a control board or even more likely your fridge is cooled by a heating element on electricity or a flame on propane. Not sure if there are separate elements for 12 volt DC and 120 volt AC but I would assume so. Opening the outside panel should allow you to check the element. There are YouTube videos describing everything you need to do.

 

[maki2]

Hello. I have a Dometic 3 power sources fridge. Being new to this MoHo thing, I was wondering about running it on 12v. The thing works well on 240v hook up and on gas. But when we are either stationary engine off in a carpark etc. or on the move, the 12v led flashes, red triangle flashes and beeper sounds. So it's not working on12v. All other 12v stuff works and leisure battery shows 12v and vehicle battery shows 12.5v. Not sure what to look for next. Many thanks for your time.

Look at the manual for your fridge model. There will be a troubleshooting tree in the manual. It will help you diagnose this issue step by step.

If you do not have the manual search for a copy of it on the internet. It is good to always travel with the manuals for all your appliance and devises including a repair manual for your vehicle. That is part of becoming self reliant when living life on the road. You might not be able do the repair yourself but then again you might be able to.

 

[abnorm]

There's no such thing as a 240 volt RV hookup....30 and 50 amp are both 120 volt

The 12 volt is only a maintainer while traveling....

I think you have battery issues.......Dry Battery ?.........the lights see 12 volts but no power on demand

RV alarm's don't have multiple displays on each system..........The 12LED says your battery is low.......and the Beep and the flashing Triangle usually refer to the gas OFF

 

[bullfrog !]

Escapees RV club has a “Boot Camp” that covers all things a new RVer needs to know, usually at their winter gathering as well as many state gatherings for their chapters. It would be well worth joining and attending if you are new to all this in my opinion.

 

[user 22017]

There's no such thing as a 240 volt RV hookup....30 and 50 amp are both 120 volt

The 12 volt is only a maintainer while traveling....

Sorry to change the subject, but why is that referenced sometimes? Last night I came across 240 volt in an article about minisplits. The author said 12,000 btu minisplits in a RV would require 240 volts, whereas a 9000 BTU can use 30 and 50 amp. It is confusing.

 

[abnorm]

The power pedestals at any campground/RV park and all RV's are wired the same......120 Volt

Residential supplied power is standard 240 volt

 

[maki2]

Sorry to change the subject, but why is that referenced sometimes? Last night I came across 240 volt in an article about minisplits. The author said 12,000 btu minisplits in a RV would require 240 volts, whereas a 9000 BTU can use 30 and 50 amp. It is confusing.

Are you reading articles on RV and camper vans or camper car electrical power from other countries in Europe, Australia, New Zealand? That would account for those 240v statements that are confusing you.? Their power system is not the same as the USA standard. So pay attention to country of origin the electrical advice is coming from.

 

[bullfrog !]

It gets even more confusing when you discover there are phases of AC power. Most all RVs in the United States use a 30 amp or 50 amp single phase 120 volts. A 50 amp plug in in a garage or house is different than a 50 amp plug in an RV. Grid power in this country offers the use of multiple phases to get higher voltages and therefore higher amperage. A 50 amp plug in in a house in the United States is usually 240 volts multiple phases. Again it pays to check before you plug in and consult an electrician if you are planning on plugging in your RV to the grid with an unknown source.

 

[independent]

Hello. I have a Dometic 3 power sources fridge. Being new to this MoHo thing, I was wondering about running it on 12v. The thing works well on 240v hook up and on gas. But when we are either stationary engine off in a carpark etc. or on the move, the 12v led flashes, red triangle flashes and beeper sounds. So it's not working on12v. All other 12v stuff works and leisure battery shows 12v and vehicle battery shows 12.5v. Not sure what to look for next. Many thanks for your time.

Hi, just to let you know 3 way fridges are very inefficient on 12v. The one I had ran 10a continuously. Reason they don't work so great on 12v is 3 way fridges work with an older style of refrigeration technology which uses heat to evaporate an ammonia refrigerant to have the subsequent change of state to create the cooling effect.

Compressor fridges use a compressor. 12v or 12/24v fridges use specialised low voltage compressors. It makes for a massive difference in efficiency. Hope this helps.

Basically 3 way fridges work best on gas and need to be level to work properly and be safe.