A camper worth waiting for

[flossandfredsadventures]

Building a compressor type fridge is not a big issue. The build for me was the easiest part once I accessed the parts but getting a person to charge the system with gas was a way harder undertaking. Most fridgies just did not wish to get involved ended up getting an A/C guys to do what needed to be done

I just read through your fridge build, very impressive! Seems relatively straightforward compared to what I thought it might entail. If I end up with an odd space where the fridge needs to go I don't think I'd hesitate to have a go myself. Always a pleasure to see someone challenge the norm.

 

[Witchdoctor Oz]

Happy to help if you need some. flossandfredsadventure

 

[flossandfredsadventures]

Has anyone else that's gone gasless considered Air Fryers as an oven in their camper? Or has anyone got one at home? Obviously they draw alot of power (around 2000w) but if its being run from a 3000w low frequency inverter connected to 800Ah of lithium the high current should be acceptable. What interests me most is that they seem to be fairly efficient at cooking the food and only usually need to run for 15-30mins equating to 5-10% of battery capacity respectively. Not to mention that they're about 1/20th the cost of a diesel oven... My girlfriend is a chef and we have an oven in the current motorhome so it will come as quite a compromise if we have to do without one altogether.

Penny for your thoughts?

As an update on the rest of the build design stage I think I'm leaning more towards a MWB FG84 so I have a bit more space to accommodate full time living. I also ordered my CNC router which I'm very much looking forward to putting together and utilising as much as possible throughout the build. I know it's not exactly an essential tool but I think it'll just about pay for itself if all I have to buy to fit out the structure of the interior is a few packs of 8x4 lightweight ply or something similar. We're plunging into winter over here so the cold dark days will be perfect for planning out my systems!

 

[Ozrockrat]

The air fryer not only draw a lot of power but it pulls constant power (doesn’t seem to cycle like when an oven gets up to temp). Even in our house I cannot run one on the same circuit as either the microwave or toaster (microwave actually stalls).

If I can find my Kill-a-watt meter I will see what it actually does pull.

While my wife is not a chef she does have every kitchen gadget know to man (or at least the pampered chef catalogue) and is fairly good with them ( . To get around the lack of an oven we have agreed to try a combination of a Bedourie oven (camp oven but lighter) and one of the Coleman stovetop ovens (but you still need a gas cooktop or BBQ). We did look at the solar ovens but there was too much real estate required.

Not that it helps with your oven/fryer question but one of the negotiating points I conceded to hep with the lack of a real oven was allowing her to bring a Sous-Vide gadget. Hopefully it will be used on the inverter while we are driving (290 amp alternator plus 840 W solar).

 

[flossandfredsadventures]

I did wonder if they cycled on and off to achieve the temperature control or just turned down the power and stayed on. If you happened to have a watt meter out the next time you've got some chips on that would be useful information! I've looked at the Omnia stove ovens as well which seem like a clever design but they aren't suited to induction cook tops (which also draw around 2000w on high and don't cycle). At least if I decide to give it a try it's a very small outlay for a second hand unit to test feasibility.

 

[Bris31]

..................
structure of the interior is a few packs of 8x4 lightweight ply or something similar.

A very good alternative to plywood can be Celluka board especially if you want to cut down the weight. Beside it is much lighter, it has similar properties when it comes to strength, cutting, nailing, screwing, drilling, gluing etc (also moisture proof, fire retardant and self-extinguishing). But more expensive than plywood. I used it inside my camper for drawers, bench & seats. I gave measurements of all the bits & pieces to the shop where I bought the board and they did the CNC cutting - for free.

 

[steve66]

The cheaper induction cooktops do indeed cycle and very quickly, you have to pay bigger money to get one that doesn't, for instance the $50 portable single burners all cycle as does my built in $200 2 burner job, Have you looked at a microwave/convection for an oven?, ours has a built in breadmaker but sadly they are no longer produced.

Cheers Steve

 

[gait]

Building a compressor type fridge is not a big issue. The build for me was the easiest part once I accessed the parts but getting a person to charge the system with gas was a way harder undertaking. Most fridgies just did not wish to get involved ended up getting an A/C guys to do what needed to be done.

I used vacuum insulated panels for diy 150 l fridge/freezer (about 8 years ago when solar was expensive). Bought a Danfoss (now Secop) BD35 already made up to have condenser, and an evaporator ready charged with refrigerant. Assembled fridge then plugged evaporator into compressor.

If doing it now I'd probably use more conventional insulation, still keep fridge and compressor separate, and have separate fridge and freezer with two compressors.

The pulsing of two "burner" induction is not a problem to 3kW inverter on 300Ah Li. We know the power for each number and make sure they don't add up to more than 15 (of possible 18). More important than the pulsing was start on zero when turned on.

 

[flossandfredsadventures]

A very good alternative to plywood can be Celluka board especially if you want to cut down the weight. Beside it is much lighter, it has similar properties when it comes to strength, cutting, nailing, screwing, drilling, gluing etc (also moisture proof, fire retardant and self-extinguishing). But more expensive than plywood. I used it inside my camper for drawers, bench & seats. I gave measurements of all the bits & pieces to the shop where I bought the board and they did the CNC cutting - for free.

That product sounds perfect for the internal fit out of a camper. The lightweight Falcata plywood that Wyuna suggested a few pages back is in fact even lighter at 0.37g/cm3 compared to the 0.55g/cm3 of the Celluka at 1/3 of the price. It doesn't have some of the excellent properties of course and it still needs to be painted. I'll add the Celluka to my research list for sure.

The cheaper induction cooktops do indeed cycle and very quickly, you have to pay bigger money to get one that doesn't, for instance the $50 portable single burners all cycle as does my built in $200 2 burner job, Have you looked at a microwave/convection for an oven?, ours has a built in breadmaker but sadly they are no longer produced.

Cheers Steve

That's interesting, I didn't realise they cycled like that. Would that equate to less overall consumption? I did look at the countertop convection ovens but came to the conclusion that they needed to run for longer at the same power draw due to the air not circulating as quickly and that they would take up slightly more space (because they had a bigger cooking capacity). The quality of the finished baked goods seems similar from what I've read.

I used vacuum insulated panels for diy 150 l fridge/freezer (about 8 years ago when solar was expensive). Bought a Danfoss (now Secop) BD35 already made up to have condenser, and an evaporator ready charged with refrigerant. Assembled fridge then plugged evaporator into compressor.

If doing it now I'd probably use more conventional insulation, still keep fridge and compressor separate, and have separate fridge and freezer with two compressors.

The pulsing of two "burner" induction is not a problem to 3kW inverter on 300Ah Li. We know the power for each number and make sure they don't add up to more than 15 (of possible 18). More important than the pulsing was start on zero when turned on.

What would sway you to run two compressors? I went away from that thinking as I figured it would be more efficient to only have to run one?

I guess the pulsing isn't like starting a pump, it will just draw its rated current. I was actually planning to run two 3kw inverters (one cheap high frequency and one a more beefy low frequency) to be able to safely power one hob each. I assume your 'burners' are around 2000w each too Gait, do you find you ever run them on high? I would normally just go ahead and test these products for myself but it seems wasteful to buy them here in the UK when I need them in Aus. I appreciate all the feedback you're giving me to supplement this limitation.

 

[gait]

delonghi cooktop two "burners" are 1400 and 2250w, total 3650w. We only really use "9" (2250w) to boil the kettle.

fridge and freezer off one compressor is a bit of a compromise trying to control both temperatures. Carcass needs for fridge and freezer are a bit different. I haven't done the maths on two compressors, just a feeling and an awareness of the carnot cycle.

the BD35F is not really as efficient as the inverter compressors in mains powered fridges. If there were a small inverter fridge I'd buy one. Someone somewhere will hack one so it can run off 12v.

 

[flossandfredsadventures]

We only really use "9" (2250w) to boil the kettle.

I thought that might be the case. Do you have any power consumption figures for your fridge? My front runner at the moment is a 175L upright fridge freezer from EvaKool (Secop PBC2.5 aka BD50) with a quoted 50Ah/24hours.

 

[gait]

fridge freezer 150 L about 25 Ah/day at 25 deg C ambient ........ somewhere I have a chart of energy use vs ambient temperature. Separating carcass and compressor meant surface area small increase volume large increase. Compressor speed is variable (slower equals more efficient, better insulation allows slower speed, and so on). Drawers. But as mentioned earlier, the economics are different now, solar is cheaper than vacuum panels (haven't checked but both have come down). Some people simply add insulation around a commercial fridge.

 

[flossandfredsadventures]

pleased to help

its just a box!

a couple of other memories -
separate compressor from carcass, easier to build, increases volume for small surface area increase, easier to get good air flow over compressor/condenser - most efficient is low condenser temperature,
consider seperate fridge and freezer,
add a switch with resistors into the secop/danfoss compressor thermostat circuit to change speed (lowest speed most efficient but may not keep up in really hot conditions), the marine guys have controllers that do that automatically,
check it fits through the door
also, since I built my fridge household fridges have improved while RV fridges have been fairly static.

here's the numbers - one of the problems is that there's no (that I can ever find) similar data for commercial fridges and everyone who ever installed a fridge reckons their's is best. I was once a wannabe combustion engineer with industrial oil fired metallurgical furnaces to play with - all the same principles.

View attachment 237326

Found the chart, very interesting. Outback Marine even sell such a speed control unit - https://www.outbackmarine.com.au/frigoboat-thermostat-speed-controller

At the least, do you think adjusting the speed of the compressor on the EvaKool would make much difference? Surely that energy consumption has a direct correlation to the quality of its insulation so running the pump at a lower rpm will just mean its running for longer? As you say, the combination of excellent insulation and the lower rpm gives you the decreased power draw. I like the idea of the inverter fridge but I too need a short one so have ruled them out. I'll just need to decide whether the saving of approximately 4% of my usable battery capacity per day is worth the extra time of building my own fridge. After a quick look at the price of the components, I don't think it would work out a whole lot less expensive in the grand scheme of things.

 

[flossandfredsadventures]

I got windows and elec steps via him

Which elec steps did you go with Steve?

 

[gait]

My speed control is manual (a rotary 4 position switch with resistors). Its mostly on lowest speed. Yes, cycle time on is longer but uses less energy while running which is overall less.