Rv instalation 48v vs 12v batteries

[strugglebus]

Add to the A/C power consumption that it is better to keep the RV cool by parking in the shade. Completely true that RV insulation sucks and all the windows and roof vents add a ton of heat, so those need to be kept covered and as dark as possible. Makes living in an RV seem like a prison cell if you stay in there too long. If you do park in the shade to keep the interior cooler your panels now put out far less power. It's a catch 22.

 

[kjswiley]

My opinion as a noob who just installed a system in my Travel trailer.

For an RV 12V or 24V normally makes more sense, but since you are going to transfer it to a house after I think you are in the correct line of thinking with 48V. You might consider a larger inverter now (5000W) rather than have to buy more later, though you mention a "tiny/ mod house" so your needs will probably be modest. Personally I would build the system off from what the expected loads from the future house will be, so make sure you can handle power tools etc.

I just learned you will want to run you fridge and water heat off of propane instead of AC power, my oven is also propane. My fridge had an issue and was running all the time when plugged into AC power so was killing my battery bank in 1 night, but I am under the impression they are all pretty bad with energy so would try and not use AC Power for them. I bought a cheap residential AC powered fridge from Home Depot that uses a fraction of the energy to resolve my issue as I wanted to be less reliant on propane.

My draw for led lights and computers are minimal, I leave my radio and computers on 24/7 without any worry. AC and heat would be my only real draws, but I have not really used either as I just put my system in. Did the 8 solar panels come from space available on your roof, or because of the demand from your system...8 300W panels sounds like a lot of space up there depending on their dimensions....though your RV is larger than mine.

 

[sunshine_eggo]

Add to the A/C power consumption that it is better to keep the RV cool by parking in the shade. Completely true that RV insulation sucks and all the windows and roof vents add a ton of heat, so those need to be kept covered and as dark as possible. Makes living in an RV seem like a prison cell if you stay in there too long. If you do park in the shade to keep the interior cooler your panels now put out far less power. It's a catch 22.

Very good point.

This is also a scenario where a smaller, lightweight deployable ground array can yield massive benefits.

 

[sunshine_eggo]

For an RV 12V or 24V normally makes more sense, but since you are going to transfer it to a house after I think you are in the correct line of thinking with 48V. I might consider a larger inverter now (5000W) rather than have to buy more later, though you mention a "tiny/ mod house" so your needs will probably be modest.

I just learned you will want to run you fridge and water heat off of propane instead of AC power, my oven is also propane. My fridge had an issue and was running all the time when plugged into AC power so was killing my battery bank in 1 night, but I am under the impression they are all pretty bad with energy so would try and not use AC Power for them.

Whether or not something was wrong with yours, an absorption fridge (7.6cu-ft) running on AC instead of propane will consume about 4-5kWh/day or 375Ah @ 12V. They typicall run for 16 hours out of 24.

Propane is always the preferred method unless you have a massive surplus of AC/solar.

Given that this is a motor home, and the propane tank is likely fixed, refilling the propane tank requires driving your house to the filling station. Replacing with a comparably sized residential fridge is likely the best option. They burn about 1kWh/day for about 10cu-ft. You can typically fit a 10 cu-ft residential fridge in the hole for a 7.6cu-ft absorption fridge. The cooling unit on the propane fridge takes a lot of space. The compressor fridge has more usable interior volume.

I bought a cheap residential AC powered fridge from Home Depot that uses a fraction of the energy to resolve my issue as I wanted to be less reliant on propane.

 

[camelCase]

To put the power in that battery into the simplest terms, it has enough capacity to power a space heater for 3 hours before it's depleted. It doesn't sound like running much AC with that system is going to be very practical. I would consider getting a smaller, quieter, more efficient generator for supplemental power if AC is a high priority.

 

[kjswiley]

Whether or not something was wrong with yours, an absorption fridge (7.6cu-ft) running on AC instead of propane will consume about 4-5kWh/day or 375Ah @ 12V. They typicall run for 16 hours out of 24.

Propane is always the preferred method unless you have a massive surplus of AC/solar.

Given that this is a motor home, and the propane tank is likely fixed, refilling the propane tank requires driving your house to the filling station. Replacing with a comparably sized residential fridge is likely the best option. They burn about 1kWh/day for about 10cu-ft. You can typically fit a 10 cu-ft residential fridge in the hole for a 7.6cu-ft absorption fridge. The cooling unit on the propane fridge takes a lot of space. The compressor fridge has more usable interior volume.

Fixed . I didn't know they did that, I hate taking my tank out and driving it over in my truck....that sounds awful.

Yes, I love this fridge, and may or may not have hugged it once when walking past it haha. 350$ later and I can now go several days without sun! Ditch the old RV fridges.

 

[Bobert]

i understand we dont get the Rv until april and i

plan on doing we wont have the rv until april and will have it a month before going fully mobile as the house is sold. as of right now i am just trying to do as much research and get as much knowledge. with the set up i posted do you think it is too much power or not enough? i was getting the impression that it would be a lot

Every rig and every person has different energy needs. The only accurate way to determine that for you is real life testing.

 

[camelCase]

One doesn't HAVE to run off the frame mounted propane tank. You can get an external propane tank adapter that allows you to connect a regular propane tank that's easier to take to town.

https://www.amazon.com/Upgraded-Connection-Auxiliary-Appliances-Motorhomes/dp/B08QCKJBLY

 

[Geokilroy]

FWIW: Any time you consider battery life in a motorhome/trailer ask what kind of thermostat is being used. If it is an older turn-dial or slider to change temp, it should be changed out for a digital style. When you move the manual adjuster you don't really know how much you changed it.
With a digital type you can adjust it up or down one degree at a time. This will save either propane or power just to get to your perfect temp. My 30yr old class C rig had an old "Honeywell" turn dial adjustment. Changed it to a digital type and it made all the difference in the world for our comfort. If it was colder we bumped it up one degree. if it was not enough another degree. Same with too hot. One degree at a time till we were comfortable. Best move we could have made. Saves propane by not over-adjusting all the time. Also not very expensive (about $15-20) and I installed it myself. I only have it for my furnace as my Air Cond is a separate unit on my roof.
This also goes for a home install also. Growing up I still remember it always seemed too cold or too hot. Someone always adjusting it too far one way or the other.