Residential fridges

[wesselm]

So guys,

I hope this is the right place to ask.

Has anyone used a standard residential fridge/freezer in an off-road camper?

There seems to be a distinct lack of info regarding this topic, as all the forums that have any info is in regards to roadgoing RV's.

We're currently busy restoring a Land Rover Forward Control, which will be getting a full camper cab on the back.

For us it will be cheaper buying a 150L fridge/freezer, with pure sine wave inverter, additional batteries and solar panel, than it is to buy a 80l ARB or Engel camping fridge.
In fact, I will be able to buy 2 fridges and still have change left.

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[The_Hoff]

I know that camping fridges are built to handle the vibrations of off-road use. Is the same tru of residential/RV fridges?


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[john61ct]

Much less energy efficient if you're thinking for off-grid solar power

 

[Oka 374]

Lots of motorhomes and caravans in Australia are running AC mains powered fridges in the Rv's and have been doing so for many years, as the PO said much cheaper even including the cost of batteries, solar and PSW inverter. Most domestic fridges are rated to perform to a standard and are usually better insulated and designed than RV fridges. The only downside is that they don't have a locking arrangement for the doors but that can be overcome with a bit of ingenuity like using childproof cupboard latches.
A domestic inverter fridge can be run from a PSW inverter as small as 350 watts.

 

[wesselm]

Much less energy efficient if you're thinking for off-grid solar power

Not too worried about this, will be fitting a beefy solar panel and batteries, which are getting cheaper by the day over here.

Lots of motorhomes and caravans in Australia are running AC mains powered fridges in the Rv's and have been doing so for many years, as the PO said much cheaper even including the cost of batteries, solar and PSW inverter. Most domestic fridges are rated to perform to a standard and are usually better insulated and designed than RV fridges. The only downside is that they don't have a locking arrangement for the doors but that can be overcome with a bit of ingenuity like using childproof cupboard latches.
A domestic inverter fridge can be run from a PSW inverter as small as 350 watts.

Seeing as I would need to fix it to the camper so it won't fall all over the place, I can easily whip something up to keep the doors closed.

Thanks guys for all the replies.

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[john61ct]

If fed by solar you really want as energy efficient as possible

 

[dreadlocks]

Not too worried about this, will be fitting a beefy solar panel and batteries, which are getting cheaper by the day over here.

Famous last words, how many of these have you built to support a fridge? Average MiniFridge is over 100W + Inverter Losses taking it from 12VDC to 120VAC.. average DC fridge is like 30W and far better insulated so they run much less frequently..

Basic back of the hand math is showing you'll want >400AH just to get a few days of use and a decent way to charge that with 400-800W of solar.. ridiculous compared to a DC fridge that will do quite well with 100AH and 200W of solar.

 

[luthj]

There are some very efficient mini fridges for home usage. They are rare in the USA, as the appliance lobby defeated efficiency standards for small fridges.

The high efficiency units have great insulation, and often have lower or similar power consumption to DC native fridges. A common way to reduce inverter losses, is to get a ~200W pure sine inverter. Wire the fridges thermostat so it turns the inverter on/off, and have the inverter run only the fridge.

On the other hand, there are plenty of garbage fridges which will use 2-3x the power of a good DC native fridge. The really cheap ones have the condenser coil under the skin of the fridge, so they must be mounted with an air gap on all sides.

Its easy enough to test. Find a fridge you think will work. Plug it into a Kill-A-Watt or similar AC meter. Record how many watt-hours it uses over a couple of days in typical temperatures.


If you want a DC fridge for less money, look at the TruckFridge brand. Same parts as IndelB, at a lower price point.

 

[wesselm]

Famous last words, how many of these have you built to support a fridge? Average MiniFridge is over 100W + Inverter Losses taking it from 12VDC to 120VAC.. average DC fridge is like 30W and far better insulated so they run much less frequently..

Basic back of the hand math is showing you'll want >400AH just to get a few days of use and a decent way to charge that with 400-800W of solar.. ridiculous compared to a DC fridge that will do quite well with 100AH and 200W of solar.

Ok, some "back of hand" actual measurements puts my 350l fridge running at 70w on 230V, with startup surging to 150w.

The 150l unit I have in mind runs at 40w on 230V, and Victron's least effecient inverter running at 88%, that puts us at, say, 46w after inverter losses. 24Vdc and 230Vac reduce the already insignificant cable losses (due to very short runs) to less than insignificant.

Also, keeping in mind the running cycle of the average fridge, which is never running constantly unless you leave the door open, I do believe you should do your calculations on the back of your other hand.

It's not the first vehicle I've built, and I design alternative energy solutions for security systems daily.

Reason I don't want really want to go the DC fridge route is purely because South African agents of ARB and Engel are ludicrous to say the least.

Luthj, unfortunately those two brands don't seem to be locally available, and importing them will just about double the price after taxes and custom duty.

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[luthj]

Where are you located? IndelB has a number of brands worldwide, there might be another option. You could always go with something direct from China, but no warranty!

If you can source a danfoss/secop 12V compressor, its possible to replace the 230VAC compressor with some soldering/brazing and a fill port to recharge.

 

[dreadlocks]

Also, keeping in mind the running cycle of the average fridge, which is never running constantly unless you leave the door open, I do believe you should do your calculations on the back of your other hand.

Oh I definitely accounted for that, also keep in mind your putting it in a vehicle or trailer.. there's a many residential fridges that never shut off just sitting in a hot garage.. and at least here domestically nobody will warranty any of those new high efficiency units if they are in a garage because how much it increases the duty cycle.. ive seen my trailer get way hotter than my garage too.

My danfoss DC fridges didnt run at full duty cycle and were able to maintain freezing temps when it was >130F inside the vehicle.. you wont get performance like that out of residential units, it may not even be able to maintain its set point at full cycle in such poor conditions.

 

[john61ct]

Ah per 24hrs at 12V to include inverter inefficiencies

is the apples to apples gold standard.

I've seen Engels stay under 20Ah per day in use at moderate temp delta.

Each 100W panelage gives at best 25-30Ah per day.

A few hundred dollars more for the fridge, compared to wasting hundreds of watts worth of panels tripling your bank size and weight is worth it.

Now, there **are** Korean and Japanese ultra efficient 240V units, even stingier than an Engel, better insulation.

Not available in the 120Vac world for "regulations are bad" reasons

 

[The_Hoff]

Ok, some "back of hand" actual measurements puts my 350l fridge running at 70w on 230V, with startup surging to 150w.

The 150l unit I have in mind runs at 40w on 230V, and Victron's least effecient inverter running at 88%, that puts us at, say, 46w after inverter losses. 24Vdc and 230Vac reduce the already insignificant cable losses (due to very short runs) to less than insignificant.

Also, keeping in mind the running cycle of the average fridge, which is never running constantly unless you leave the door open, I do believe you should do your calculations on the back of your other hand.

It's not the first vehicle I've built, and I design alternative energy solutions for security systems daily.

Reason I don't want really want to go the DC fridge route is purely because South African agents of ARB and Engel are ludicrous to say the least.

Luthj, unfortunately those two brands don't seem to be locally available, and importing them will just about double the price after taxes and custom duty.

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Kry vir jou die Dometic (Waeco) by TakeAlot. Naverkope diens is baie goed.


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[The_Hoff]

Ok, some "back of hand" actual measurements puts my 350l fridge running at 70w on 230V, with startup surging to 150w.

The 150l unit I have in mind runs at 40w on 230V, and Victron's least effecient inverter running at 88%, that puts us at, say, 46w after inverter losses. 24Vdc and 230Vac reduce the already insignificant cable losses (due to very short runs) to less than insignificant.

Also, keeping in mind the running cycle of the average fridge, which is never running constantly unless you leave the door open, I do believe you should do your calculations on the back of your other hand.

It's not the first vehicle I've built, and I design alternative energy solutions for security systems daily.

Reason I don't want really want to go the DC fridge route is purely because South African agents of ARB and Engel are ludicrous to say the least.

Luthj, unfortunately those two brands don't seem to be locally available, and importing them will just about double the price after taxes and custom duty.

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Kry vir jou die Dometic (Waeco) by TakeAlot. Naverkope diens is baie goed.


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[wesselm]

Kry vir jou die Dometic (Waeco) by TakeAlot. Naverkope diens is baie goed.


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Sal bietjie gaan loer daar. Ons is opsoek na n gemaklike grootte, met genoeg plek vir my en die vrou, asook die honde se behoeftes (haar vereiste) vir n minimum 2 weke Weskus toer.

Weet jy of daar ander Dometic agente is in die land?

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