going all electric on travel trailer - fridge, stove, water heater

circus

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Are your familiar with the Chinese 12v diesel air heater knock offs? I've got one, pretty cool. There's a water heater equivalent. No first hand experience but bet they're pretty cool. A few designs even heat air and water at the same time, some don't. Will probably have to import it. You'll be the guinea pig for us.
 

aaryno

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Jul 10, 2021
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I would be going 24v and 3000 inverter unless you want to strictly manage power.
Can use a load shed relay to cut power from the WH when the stove runs.


https://www.bestconverter.com/Automatic-Load-Shed-_c_96.html
Looking at the wattage specs... may need the 3000 to make it work.
pardon my basic question but how do i get to 24v? my battery is 12v and is not recommended for wiring in series. have been concerned that i might have to bail on this battery and get one i can run in series. also, if i run 24v, do i just put a DC converter in front of my existing fuse block?

thanks for the guidance on the old shed relay!
 

boondox

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If I was dependent on an inverter for all of my comforts I would get something better than Renogy. No dissing too hard on Renogy, I have one of their DC to DC chargers and it works fine.

I would still look at an on demand heater instead of a tank type. More expensive but it will use less power. As noted above the saving curve of an on demand leans towards lower usage scenarios. In other words, if you use a lot of hot water the saving will be less. If you use less hot water the saving will be more. And with an on demand heater you don't need to worry about running out of hot water or taking showers in shifts.

The most important thing you can do when undertaking an all electric build is a thorough energy audit. This will allow you to properly size the system so that it nether disappoints or costs more than it needs to.
 

time2roll

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Since you are already in the lithium world.... if you go 24v I recommend getting 24 volt batteries and stack them in parallel as needed.

Yes you will need a DC-DC converter to supply 12 volts to the lights etc. May need a new solar controller, although some are compatible.

I am not pushing necessarily, just making sure you have explored the options as this project goes exponential. Actually I would favor a bulletproof hold down for the propane cylinders and stay with existing systems.
 

boondox

Chief Engineer, RedNeckTech Industries
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I agree that I would stay propane but if going all electric then increasing system voltage is almost required. That is a lot of amps with a 12V system.
 

Stepandwolf

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You already mentioned the possibility to use propane outside so you could use that method to do all your cooking, taking away that induction cooker. You want to reduce electricity less, use solar heat for the water. With only 800w of solar, you aren't going to get there without a generator or running your car all day. You will also want to make the panels tiltable as the sun hardly gets over the horizon. I know a guy who just mounted a solar panel on the side of his class A for use in the south.

Taking care of refrigeration is the first concern, and that is going to take all of your solar probably.
 

Stepandwolf

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A refrigerator can be done (not well) with as little as 200W and a pwm.
800W should handle it ok I think
a single 200w panel in less than optimum conditions can in a half dozen hours generate enough amps to run the fridge all day? We aren't even talking a cloudy day :)
 

12VoltInstalls

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a single 200w panel in less than optimum conditions can in a half dozen hours generate enough amps to run the fridge all day? We aren't even talking a cloudy day :)
Assuming he’s running an 80 Watt or so fridge, yes, but I did say not well.

As an experiment I ran a 120VAC 120W fridge for six or seven weeks a few years back with 200W of panel and two nine- or ten-year-old deep cycles. The second coffeemaker run in the am sometimes struggled, but it did it. I’m not recommending that it was just entertainment value: could I do it?
I did, but I’m not proud of it LOL :)

So technically you *could* run a fridge on 200W but I’m not recommending that.
 

aaryno

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Jul 10, 2021
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Thanks so much for the great discussion. I'm feeling pretty dense because I'm still pretty confused about things so I'm going to try to sum up:

Water Heater Summary:
on-demand flash heater: 1.41kW output, 30A at 120VAC or 3600w, which for 30 mins/day is 1800wH. With a 90% inverter efficiency would be ~85Ah on a 12v battery (boondox). may be preferred over a tank since water conservation is a goal aligned with energy conservation
to convert a tank WH, replace the plug with a heating element, 400 watts at 110VAC (time2roll). I don't know how much energy that would use over a day but for the sake of a calculation, let's assume 6-gallon tank and it's emptied once at the end of the day.
circus suggests being a guinea pig for a Chinese 12v diesel air heater knock off for water 😬
prof farnsworth also suggests on demand can work, but run 24v instead of 12v to keep amperage low
solar heat water if you can (stepandwolf)

Refrigerator:
Go for a compressor fridge with Danfoss compressor. compressors seem to take one of 12v, 24 DC or 110VAC. isotemp water heater is recommended https://www.indelwebastomarine.com/us/products/isotemp-water-heaters/basic/ - comes with 115 or 230VAC compressor

Inverter:
3000w inverter and avoid Renogy (time2roll, boondox, prof farnsworth).

Large draws:
Use a shed relay to cut power from WH when stove runs (thanks time2roll!)

12v vs 24v:
24v (prof farnsworth, time2roll, boondox) with 24v batteries in parallel - will need DC to DC converter to run to 12v fuse block for lights, etc

propane vs electric
everybody: keep the propane if you can

---

My response:
I'm hoping that we can go back to propane but so far there's a hard no coming from my better half so I need to put this together to 1) understand what we are getting into with all-electric and 2) use as evidence to put back the propane or 3) make this all-electric conversion work for us. So, sadly, propane is not really going to work right now :-\

Sounds like the overwhelming suggestion on the base system is to make this work with 24v batteries in parallel. With my current setup (Renogy rover 40A mppt charge controller and 400w solar) the charge controller specs say "24V @ 1040W" but my first battery is 100Ah 12v Renogy battery which explicitly can only be run in parallel. So does that mean this battery is a dead end for me in this scenario? Would it be too much to string multiple batteries in parallel and then boost 12v to 24v for the short run to the inverter?

I will need a new inverter, 3000w, and something more reliable than Renogy. Need to ultimately do the energy budget but this seems likely already.

Refrigerator:
Find a fridge with the 12v compressor. It will probably use half or most of the energy produced by the 400w of solar running at 5-6A most of the day, but maybe less.

Water Heater:
Still most confused about this. What would be the minimum GPM I would need for a shower? I read that 1.5 GPM is standard low flow but the point-of-use water heaters I see that use less than 2kW @110VAC are 0.4 or 0.2 GPM. OTOH, here's a 4-gal tank that uses 1.4kW @110: https://www.zoro.com/bosch-4-gal-12...k-water-heater-es4/i/G3114273/#specifications

Stove:
Not much feedback here except we should install the shed relay to keep the hot water heater from turning on while running the stove. And cook outside with gas. It would be nice not to have to set up a grill outside every time we want to cook so we'd really like to make the stove work. Looks like the induction cooktop I mentioned at the beginning will use almost the whole capacity of the existing inverter, though I recognize that will. have to get upgraded.

----

Finally, TL;DR:
1) Can I use my existing battery to build a bank that will support a 24V system even though they cant be run in series? Should I?
2) Recommendation for a water tank?
3) Suggestions on an inverter?
 

Stepandwolf

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3) Suggestions on an inverter?
I went with the Victron Multiplus II as many have but you are also getting a battery charger and automatic transfer switch with the system which you might not need, but I did.
 

Stepandwolf

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There are a number of great 80W 120V fridges. And not that expensive. That is worth exploring imho
The small cooler type fridges or bigger ones like the typical TT style? I can't fathom how a larger size fridge can run on such few watts. Do you have links so I will know what I can buy if I ever need replace my fridge.
 

Stepandwolf

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I would bet it uses a danfoss compressor


  • Rated Voltege: 12/24v Rated Current: 5A Rated Power 80W Total Storage Capacity: 98L
  • Solar Panel: 300W 18V Battery: 150aH 12V 1 Set
  • Carton Dimensions: 462*495*856MM
  • Temerature: 0-10oC fridge'-18oC Freezer
  • Power Consumption: 0.6kwh/days Input Voltage: AC 220V or AC to DC 12/24V
  • Refrigeration: Direct Cooling 40HQ: 340PCS

That is only 3.5 cu ft which is about half of the size of my fridge, and I don't have a big one :( I see they offer a 9 cu ft one, and interesting, they are still claiming 80w. Something fish there.
 

Stepandwolf

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You're right it can't be done :rolleyes: ... no use in searching Solar Fridges ;)

Maybe the foam is thicker... then you have surface area vs volume
All it tells me is they probably have one refrigeration unit they put in all models, or so it seems. It might work fine with all, but it won't cool them all equally. Longer to make ice, to reach set temp after restocking at Wally World, etc.
 

Supervstech

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I repair commercial coolers and freezers, below a certain size they all use about the same wattage, it all depends on door frequency, and product changeover.
Residential coolers up to a single wide tall deck all use a small freezer box, and pump cooler air from below the frozen coil.
Dorm coolers have styles that use a cooler plate, some freeze, some only cool.
The boxes with freezer compartments use a freezer coil, and gravity or a small fan to chill the cooler section.
 

jberger

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Jun 1, 2021
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FWIW, we are all electric in our current RV with induction cooktop, 120vac fridge, etc.
The idea of a propane fire or propane fridge fire is exactly why we wanted to go all electric.
I'm so glad you and your family made it out ok, these vehicles burn INCREDIBLY quickly once they ignite, you are very fortunate.

The induction cooktops are awesome, they heat very quickly, and dump much less heat into the space. It finally convinced my wife to let me upgrade our range at home to induction as well.

Have you thought about using a diesel fueled unit for hot water and heat?
We have an Aquahot unit that we can use for both, and would really cut down on the battery bank needed to run it. Diesel doesn't ignite like Propane or Gasoline, so the fire risk would be much lower which should make your wife happy.

You might be able to get a full size fridge that actually uses less energy than a propane unit, our full size Samsung uses less than the Norcold it replaced, and it's much larger on the inside. We never had any good luck with the 12v fridges in prior uses, they just don't seem to cool fast enough and the ones that did used a ton of battery power to make it happen.

Check out Bontragers for RV specific surplus units, they have an ebay store: https://www.ebay.com/str/bontragersrvsurplus?_pgn=5&rt=nc

Also find the RV Salvage Yards in your area and look for the diesel fired hydronic heaters, induction units, basement chest freezers, etc. It's a very cheap way to get what you need without paying full price. You will be STUNNED at the number of burnt units you will find on the lots and how many of them started with fridge. . .
 

Stepandwolf

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Most cold stuff is already cold, like beer ;) meat and so on.
The typical shopper in our local grocery store shops from the right side to the left side. They get the refrigerated and frozen items on the right s of the store and then wander through the rest of the store, then dealing with lines to checkout and then getting to your vehicle, etc. I shop refrigerated items second to the last, then frozen. I also bring insulated shopping bags with me to hold the items as I shop, then checkout, and then back to my SUV.

There are many items like the soda pop which likely wasn't cooled, condiments, and things I would like cold before eating them, like pickles. Anyway, my shopping habits probably aren't of interest here, but even my Dometic doesn't cool like I would like it.
 

12VoltInstalls

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The small cooler type fridges or bigger ones like the typical TT style? I can't fathom how a larger size fridge can run on such few watts. Do you have links so I will know what I can buy if I ever need replace my fridge.
There are 10-12CF 120V fridges 80-120W that you can order from Home Depot or wherever
I use a 4.x cubic foot, yes small- but $147 delivered to me from walmartha. I selected it specifically because it barely was big enough for my needs AND advertised 85W running. My inverter display, however, varies between 60W and 80W running.
It’s not the best but the best was $1400 for a 10.x CF that claimed 85W and had a separate top freezer.

The point was you can spend shorter dollars on commodity items, or you can spend tall dollars on the best equipment. You choose according to your own priorities.
 

Q-Dog

¯\_(ツ)_/¯
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Dec 22, 2020
Messages
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FWIW, we are all electric in our current RV with induction cooktop, 120vac fridge, etc.
The idea of a propane fire or propane fridge fire is exactly why we wanted to go all electric.
I'm so glad you and your family made it out ok, these vehicles burn INCREDIBLY quickly once they ignite, you are very fortunate.

The induction cooktops are awesome, they heat very quickly, and dump much less heat into the space. It finally convinced my wife to let me upgrade our range at home to induction as well.

Have you thought about using a diesel fueled unit for hot water and heat?
We have an Aquahot unit that we can use for both, and would really cut down on the battery bank needed to run it. Diesel doesn't ignite like Propane or Gasoline, so the fire risk would be much lower which should make your wife happy.

You might be able to get a full size fridge that actually uses less energy than a propane unit, our full size Samsung uses less than the Norcold it replaced, and it's much larger on the inside. We never had any good luck with the 12v fridges in prior uses, they just don't seem to cool fast enough and the ones that did used a ton of battery power to make it happen.

Check out Bontragers for RV specific surplus units, they have an ebay store: https://www.ebay.com/str/bontragersrvsurplus?_pgn=5&rt=nc

Also find the RV Salvage Yards in your area and look for the diesel fired hydronic heaters, induction units, basement chest freezers, etc. It's a very cheap way to get what you need without paying full price. You will be STUNNED at the number of burnt units you will find on the lots and how many of them started with fridge. . .
How much battery and solar do you have and are you fully off grid like OP wants to be?
 
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