Generator vs. A/C propane drain

[Solera]

I was reading some good info on how long the generator in my new 2015 Solera 24W will run on the propane tank onboard. The answer given was 13 hours with the A/C on full time.
If that is correct it means that I have to go fill the propane every day if I want to run the A/C off of the propane while boon docking. Is this true? Seems ridiculous that a generator was installed that only runs for 13 hours on the onboard propane.
I would love to hear your experience or intel on this. Thanks.

[Beach Bums]

On another string I recently shared a summary from Onan that confirms what you share. Actually, that is the max time IF at full load. The current solution some are pursuing is the connection of an auxiliary tank.

[Solera]

I think it was you who gave me those numbers. Really??? I truly cannot believe that running my A/C will use up all my propane in 13 hours. I have had RV's my entire life (I am 66 now) and have run A/C for days on end at times but not on propane. That was using gasoline for the generator. This is a terrible system if its the one I have. Yes, the answer is a 50 gallon LP tank mounted on my Yakima roof rack on top of my Solera. Wonder if Yakima offers that.

[Solera]

Thanks for the response on this. Good to know someone knows the numbers on this propane and A/C combo.

[Jim Schings]

Using this chart you can calculate typical propane usage.


Propane and propane generators

[MarsMan]

In the Prism MH I have a 20 Gal tank- approx 88lbs of propane-using my 3.6 KW Onan I would get approx 40 hrs of run time. We recently ran the genny for about 24hrs over 4 days and we will had 1/2 tank of propane (verified when refilled). We also have been using the LP to run the fridge and heat water. just 1 A/C unit and it cycled on an off. Seems like I may get a bit better than 40 hrs (if I had to). I am certain the load averaged less than 50%. I wonder if there is room for an AUX tank in the underbelly? Have not hear of anyone doing that in the MBS type MHs. That is something I would keep as a back up (of use exclusively for the fridge and HW heater) I think we have to develop a mindset of thinking of ways to minimize energy use as much as possible when boondocking. Thought about the diesel genny.... was worried about noise and they do seem to be a bit harder to start.

I just installed 200W of solar. That will help with the coach batteries. Wont help much with the A/C or ov/micro. If I park in shade to keep the MH cool, the solar does not work as well (obviously). We have been experimenting with the orientation of the MH. We have no windows at the back and just 1 bigger one on each side. If we keep the nose away from the sun we can keep heat gain down and the panel(s) exposed. It all adds to the fun!! I love the challenge. O yea I also installed a switch to allow us to put a solar charge to the chassis battery. (just in case)

[MOODMAN]

On a related note, I have a question about what generator to buy.

My 5er has two air conditioners and plugs into a 50A circuit.

I may buy a generator in the future, but want one with enough capacity to run my onboard systems, especially the AC.

So how many watts is "enough" for my needs? I don't want to buy one that is too large, but also one that is not too small. Too large will use too much fuel, and not enough will just frustrate me.

Advice???

[j free]

I have the cummings propane geni and I replaced my 20# tanks for 40# tanks. I can go about 12 to 13 hours on a 40# tank. I use to have a gas cummingsnan on my old 5er and the fuel usage was about the same gal for gal. I do a lot of Nascar boon docking and I installed 2 extra 40# tanks in my storage compartment so I have 5 40# tanks with me on those trips and can go all 5 to 6 days without needing to refill. My old gas geni would use about 35 to 40 gal of fuel for the same time period. I have the cummings 5500 it has 50amp and can rum both ac's.

[Solera]

I can see I need the propane truck to follow behind me on my boondocking trips. Need more propane.....thats the answer. So I will look into another tank in a storage area.

[Jim Schings]

Originally Posted by MOODMAN

So how many watts is "enough" for my needs? I don't want to buy one that is too large, but also one that is not too small. Too large will use too much fuel, and not enough will just frustrate me.

Assuming 2 13K BTU units, 8 KW will make it easy. You could get buy with 6 KW if you are careful. (ie. no microwaves, hair dryers, or coffee makers with A/C running. )

[DickiedooFlagman]

Running a generator takes energy to create the power to run air conditioners. Here is a Wiki comparison showing BTU equivalents to one gallon of gasoline. https://en.wikipedia.org/wiki/Gasoli...lon_equivalent

Gasoline has 114,000 BTU per gallon
LPG has 84,300 BTU per gallon
Diesel has 129,500 BTU per gallon

My conclusion is that it takes significantly more propane by volume to equal the same energy as a gallon of gasoline. Diesel is even better.

[pdqparalegal1]

Propane doesn't have the BTU per gal. of gas or diesel, thus you need MORE of it. I had 1 MH with propane, should read PITA. Drained the propane saddle tanks in 30 hours on a hot weekend. Gas and diesel draw from onboard tanks and last longer!

[jdyson]

On my new 2016 Forester MBS 2401 R we have the smaller LP tank. I wanted the 15k ac and heat pump unit. For that, the LP generator is required since the diesel cannot power the 15k unit. I've heard that an LP retrofit for a larger propane tank might be an option. Does anyone know if that's true?

[Pod2Vibe]

The new FR Coachmen Prism MBS has a 20 gallon LP tank. That part # may be great place to start as a retro.

[strat56]

Originally Posted by MOODMAN

On a related note, I have a question about what generator to buy.

My 5er has two air conditioners and plugs into a 50A circuit.

I may buy a generator in the future, but want one with enough capacity to run my onboard systems, especially the AC.

So how many watts is "enough" for my needs? I don't want to buy one that is too large, but also one that is not too small. Too large will use too much fuel, and not enough will just frustrate me.

Advice???

Originally Posted by Jim Schings

Assuming 2 13K BTU units, 8 KW will make it easy. You could get buy with 6 KW if you are careful. (ie. no microwaves, hair dryers, or coffee makers with A/C running. )

50 amps = 6,000 watts (6kw). Formula is amps * volts = watts.

As Jim said, 8,000 watts (8kw) will make sure you have no issues. Generators have a max output and a continuous output, an 8kw peak with at least 6kw continuous will work for you.

[Beach Bums]

Originally Posted by Pod2Vibe

The new FR Coachmen Prism MBS has a 20 gallon LP tank. That part # may be great place to start as a retro.

I am sure you know this (I did not clearly understand it until recently realizing my tow vehicle was going to be a propane tanker truck)....but 20 gallons of LP is better than two times what our 2016 FRF MBS will have (9.8 gallons). I am not sure that would have changed our purchase decision....but it would have at least made it on our pro/con decision list.

[Solera]

It would have made it on my pro/con list as well. I think its crazy that there is an LP tank which at best can run my AC for 13 hours or so. Thats nothing. It should be able to run for days and days if necessary as have my other Motorhomes. My Monaco had a 5K genset and it could run on gasoline for five days full time in 90 degree daytime heat and 75 at night.
Some reading this may think that I am an AC nut or allergic to heat. Actually I love hot weather and love boondocking without any AC. Its just that a $100K motorhome should have the capability to use the AC for much longer than it does. Very disappointing but never asked the salesman about this. Just assumed it was like the rest of my RVing experience.
My solution is to carry another full LP tank which is heavy and takes valuable space in a 24 foot motorhome, but thats what I will do. I already ordered the attachment that goes from the OEM LP tank fitting to the outboard tank. Some use the Extend a Stay for this.

[Pod2Vibe]

Originally Posted by Beach Bums

I am sure you know this (I did not clearly understand it until recently realizing my tow vehicle was going to be a propane tanker truck)....but 20 gallons of LP is better than two times what our 2016 FRF MBS will have (9.8 gallons). I am not sure that would have changed our purchase decision....but it would have at least made it on our pro/con decision list.

It would have made me think more about it, as well.

The Prism does loose towing capacity due to that and other things, though. It is @ 3500 lbs vs. the Solera @ 4200 lbs.

[RedLdr1]

I was lucky in that I'd read about the propane generator issue here and my dealer was aware of it as well. Based on that info we ordered our 2400W with the optional QD3200 diesel generator. That is an expensive option to fix the problem though...

If I recall correctly FR is trying to figure out what to remove to make room weight wise for the larger LP tank. The glass door in the shower was one item I think was mentioned as a possible weight reducing move. Even though we have the QD I'd still want the larger LP tank for other uses if it is offered for retrofit.

[jdyson]

I wanted the 15k btu heat a/c with heat pump option, which I was told the diesel genset would not support. Having installed Sumo Springs, I'm thinking of putting on the larger propane tank, and maybe removing the stabilizers. Maybe.