Can you use two MPPT controllers with a total charging amp higher than the battery?

[sunshine_eggo]

The goal is to have as little maintenance as possible, so I won't want to add propane to my RV constantly. The built-in tank only holds about 15 lb., so I would like to use a mini-split for both heat and cold.

That's a really small tank. Are you sure? The typical grill tank is 20lb. is it smaller than that? Do you maybe mean it holds 15 gallons? That's closer to 2X 30 lb bottles.

Summer cooling is likely not an issue, but winter heating will be. We can run our garbage rooftop RV A/C for about 7-8 hours on 6kWh usable of FLA and 3kW of solar.

Assess your actual heating needs. Is your climate such that you likely won't need heat in the middle of the day?

With outside temps of 25°F, we are comfortable with the propane furnace preventing the pipes from freezing keeping the interior at 45°F and using an electric blanket to keep us very very toasty. Mornings are brisk, but as you know, RV insulation sucks, and we take on a lot of heat even when it's only ~50°F outside.

 

[Dzl]

The goal is to have as little maintenance as possible, so I won't want to add propane to my RV constantly. The built-in tank only holds about 15 lb., so I would like to use a mini-split for both heat and cold.

15lbs or 15 gallons? 15lb is less than a BBQ tank, that does indeed sound pretty limited for an RV.

 

[HRTKD]

Not sure how do you keep the room cool? In South California, I would need my heater inside my house in winter, and my RV is at 100F under the sun. I felt I would need ~4kwh every day just for a mini-split.

A requirement to use air conditioning all day long, and perhaps well into the night, brings your system into a whole different level.

Have you gone through all your loads to figure out what your total power requirement is?

If you can't get enough PV on the roof, then you'll have to look at alternate solutions like ground deployment. There's only so much room inside an RV for batteries and only so much room on the roof. Some compromises may need to be considered.

 

[Riley]

That's a really small tank. Are you sure? The typical grill tank is 20lb. is it smaller than that? Do you maybe mean it holds 15 gallons? That's closer to 2X 30 lb bottles.

Summer cooling is likely not an issue, but winter heating will be. We can run our garbage rooftop RV A/C for about 7-8 hours on 6kWh usable of FLA and 3kW of solar.

Assess your actual heating needs. Is your climate such that you likely won't need heat in the middle of the day?

With outside temps of 25°F, we are comfortable with the propane furnace preventing the pipes from freezing keeping the interior at 45°F and using an electric blanket to keep us very very toasty. Mornings are brisk, but as you know, RV insulation sucks, and we take on a lot of heat even when it's only ~50°F outside.

I checked the user manual. It says 1990 Minnie Winne should have a 60 lb tank, and I measured its length was 27 inches and height 13 inches, so it should be 60lb. The seller told me the wrong facts. But I am not sure I can trust an 31 years old propane tank. Does it have to be replaced?

I plan to travel in California, south, and north. It's only cold( about 60F) at night and hot in the day, even in winter.

I checked my energy generation from solar, it's more then 3x between winter and summer.

 

[HRTKD]

That's a lot of propane. I don't know about fixed tanks like that but my portable tanks have to be recertified after twelve years and then every five years after that.

Refilling it is a pain I'm sure, but I would be making use of it. Some of the places I go to there is a mobile propane refill option. It probably costs a bit more than going to their facility.

 

[Riley]

That's a lot of propane. I don't know about fixed tanks like that but my portable tanks have to be recertified after twelve years and then every five years after that.

Refilling it is a pain I'm sure, but I would be making use of it. Some of the places I go to there is a mobile propane refill option. It probably costs a bit more than going to their facility.

It'd be great if I could still use it. Otherwise, it will be $900 to get a new tank. I did some math, and it says a propane generator will cost about $1.1 per kWh, but it can offer heating while charging the battery. I still have to find a more quiet and efficient propane generator. About mobile refilling - that's a good idea!

 

[HRTKD]

It'd be great if I could still use it. Otherwise, it will be $900 to get a new tank. I did some math, and it says a propane generator will cost about $1.1 per kWh, but it can offer heating while charging the battery. I still have to find a more quiet and efficient propane generator. About mobile refilling - that's a good idea!

There are many dual-fuel generators out there. I've seen a lot of them reviewed on RV sites. These are not the built-in type, but there are also built-in generators that can use propane. I considered changing my gasoline generator to propane because I don't use the generator enough to keep the fuel fresh. But the cost to do that was going to be far more than I considered practical.

The recertification process was easy. It took maybe five minutes for two 30 lb tanks.

 

[sunshine_eggo]

That data plate likely has a recertification date on it.