Community Forums

D-n-Tyke · 01-02-2011, 03:20 PM

We are looking at a new coach and it is has a propane generator on it. I am not familiar with propane generators. used to gas or diesel. What are the pros and cons of a propane generator? Unit we are looking at is a Class A Diesel Pusher. Why would you want a propane generator over a diesel generator? Can you convert it to run of diesel?

TXiceman · 01-02-2011, 03:26 PM

The propane generators are cheaper to install for the manufacturer. Next, check the propane usage rate and see how long your propane tank will last. Propane generators will suck up a tank relatively fast.

No such thing as converting to diesel...a propane engine will have a compression ratio of about 8 or 9 to 1 and a diesel will be 18 to 1 range. Totally different engine designs.

Ken

a k · 01-02-2011, 03:30 PM

I have a 25KW propane at the house and fully loaded it sucks over 4gals/hr at $2.69/gal.

But it's worth it when you need it.

W4RLR · 01-02-2011, 05:27 PM

Propane burns cleaner. You also have propane tanks in your rig. Some manufacturers install gasoline generators, then you have THREE fuels to contend with. You could take A K's example and cut the fuel consumption in have for a 12Kw generator at full load. A 4K generator that I am considering consumes about .6 gallons of propane an hour at full load.

It is possible that your propane generator could be converted to use gasoline, but then you would have to install a gasoline tank. No way to convert it to diesel. Your only other option would be to install a diesel generator.

BryanL · 01-02-2011, 06:06 PM

If you use the genset a lot to keep the fuel fresh or if it is a large one, then gas or diesel might do. But for a genset that is smaller or tends to have periods of inactivity, then propane is generally less of a problem because the fuel doesn't gum up or go stale. (small engine carbs are especially vulnerable).

As for burn rate, propane is about 74% energy density of gasoline (diesel 110%) by volume. By weight, though, propane is 13,900 Wh/kg, gas 12,200 Wh/kg, and diesel 13,762 Wh/kg (trasntronics) (lead acid batteries are about 45 wh/kg). So the actual burn difference isn't that much. You also should keep in mind that propane may have a tax advantage over road fuels and a propane engine may be a bit more efficient than either gas or diesel. If you are really into 'green' then propane should appeal as it burns cleaner as well.

If you have propane on board, then propane can be a very good solution for a genset.

At least, these are the sorts of things I am using to convince myself to convert my genset from gas to propane, especially with all the talk about E15 and the other things they are doing to gasoline.

powerboatr · 01-02-2011, 06:58 PM

i had a 6500 watt lp genny in our last fiver.
other than it would empty a 30 lb tank in short order (7 hrs)
it was ideal, it could sit for long periods and start right up.

RedT · 01-02-2011, 07:41 PM

A lot depends upon how much you intend to use the genset. When shopping for our new coach in '03, the price of a diesel genset was $4,500 more than a propane genset. In addition the diesel genset has it's own cooling system (coolant) plus fuel and oil filters.

Our rationale was that we seldom boondock, do not use the generator much (95 hours in the last 7 years) and were willing to spend the $4,500 elsewhere. If, however you intend to use the genset often and for long periods, refilling the propane tank will probably become a hassle for you.

Bottom line is that the diesel genset is a bit more economical in fuel burn, but the initial cost and routine maintenance costs will be more.

RedT in Glendale, AZ
'04 Meridian
'03 Jeep Liberty
M&G Brake Sys

BryanL · 01-02-2011, 08:42 PM

a 6500 watt genset uses about 1 gallon of fuel per hour? that sounds about right.

A proper referent is needed here. 30# or 7 gallons of propane is a small tank obviously not intended for much more than basic kitchen needs. Propane tanks are often quite a bit smaller than primary fuel tanks so a large (e.g. 6500 watt) genset is going to make a more significant dent in its fuel supply when a small tank is used.

That doesn't mean the propane genset is a fuel hog, only that you have a limited fuel supply for it. The example is like using a jerry can as a fuel source.

My b-van has 10 gal propane tank, a typical trailer has 2 7 gallon tanks, a 34' moho has an 80 gallon propane tank. Fuel supply needs to be sized for use requirements. It may be a limiting factor on retrofits.

RVhauler · 01-02-2011, 08:51 PM

Have an Onan 6.5KW propane on my 97 5er. Advantage is will start in cold weather immediately-quiet running-clean operating. Disadvantage is will use about 1.5 al propane per hour at full load. (IE: A/c opns). Have about 200 hours on it with only minor problem so far. The propane gens are gas sets with carbs removed and regulators installed by the factory. Problem with E10 in the gas corrodes the carb on gas and carb must be replaced. $$$. My gen is used mostly for roadside type stops (lunch/etc). I have 2-40pound bottles find those are sufficent in most cases including the operation of frig/2 furnaces/HWH at same time in cold weather

D-n-Tyke · 01-02-2011, 08:59 PM

Quote:

Originally Posted by BryanL

a 6500 watt genset uses about 1 gallon of fuel per hour? that sounds about right.

A proper referent is needed here. 30# or 7 gallons of propane is a small tank obviously not intended for much more than basic kitchen needs. Propane tanks are often quite a bit smaller than primary fuel tanks so a large (e.g. 6500 watt) genset is going to make a more significant dent in its fuel supply when a small tank is used.

That doesn't mean the propane genset is a fuel hog, only that you have a limited fuel supply for it. The example is like using a jerry can as a fuel source.

My b-van has 10 gal propane tank, a typical trailer has 2 7 gallon tanks, a 34' moho has an 80 gallon propane tank. Fuel supply needs to be sized for use requirements. It may be a limiting factor on retrofits.

Yeah, the coach we are looking at has a separate propane tank just for the gen. It has the "standard" 10 or 15 gal house tank and then a secondary huge tank, I am guessing 50-60 gal tank, for the gen. So it will probably hurt when we would have to refill it but would probably last quite awhile. We would be using this coach in the desert so the gen will get some good use. We probably use it 20 hours a weekend out there.

WeBeGone2 · 01-04-2011, 06:51 PM

Diesel is the way to go if you have a diesel M/H. Gen and furnace will drain you in short order. Not to mention water heater and stove. Resale of M/H will suffer due to propane gen. Even if you do not use it alot you will find that as the sun beats thru the windshield you WILL crank up the gen to keep the M/H cooler for you and the animals as you cruise down the highways.

38 Special · 01-04-2011, 09:21 PM

I had a propane genset on a RV a few years back. One time, we ran out of propane while dry camping and had to drop camp and go refill. No propane close, a huge hassle. After that, we watched the gauges closer and did not run it as often. Many times giving up comfort to conserve propane. Our last two motorhomes have been diesel gensets. There is no question, a propane genset would be a deal breaker.

SteveLevin · 01-05-2011, 01:29 AM

One other difference is that most of the modern diesel generators are liquid cooled, rather than air cooled, and are much quieter.

Also don't forget that you only get like a 75-80% fill on an LP tank to allow for expansion... so on a 40 gallon tank you will only have 32 gallons of propane. While that would, for example, be fine for your 20 hours of use, if you plan on running the generator to cool the coach while driving to and from places.... you might be getting really close.

Steve