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RVing message boards => Boondocking => Topic started by: Dean_Reynolds on May 16, 2019, 02:50:22 PM

Title: duo-fuel (LP and gas) gen's
Post by: Dean_Reynolds on May 16, 2019, 02:50:22 PM
It looked like there was a great thread about LP vs diesel gen recently.  I"m looking for similar thoughts about the gas vs LP duo fuel portable inverter generators.

Anyone have any opinion about which fuel would be more efficient/ cheaper to burn for a generator?
Title: Re: duo-fuel (LP and gas) gen's
Post by: Frank B on May 29, 2019, 08:28:25 AM
I am not familiar with dual fuel generators, but I did have a dual fuel vehicle some years ago.


It is my understanding that bottled propane (20 or 30 lb) is expensive for the energy you get compared to gasoline. It is convenient for the RV however, as you don't have to carry an extra jerry can of gasoline for the generator.


A dual fuel vehicle is a compromise dictated more by the availability of propane filling stations than efficiency.  In this application, the propane 'carburetor' is mounted on top of the gasoline system, which introduces airflow restrictions causing both systems to work less efficiently.  The engine will work better on either propane or gas.  If auto propane supplies are not common where you are, THEN a dual fuel vehicle makes sense.


In a vehicle, the cost advantages of bulk propane over bulk gasoline used to be considerable.  Not so much anymore.


So, in the case of a dual fuel generator for RV use, I doubt if one would ever see a cost advantage.  There may be a usage / convenience advantage, but not a cost advantage.


You did ask for an opinion.  :-)


Frank.
Title: Re: duo-fuel (LP and gas) gen's
Post by: Gary RV_Wizard on May 29, 2019, 09:10:49 AM
Propane has roughly 25% less energy per gallon than gasoline, even E10 gas, so a lot more is consumed to produce X watts of power. How that effects the economics depends on the priced of propane/LPG vs E10 gasoline in your area.  Propane prices vary widely, both by the sales source and the type of purchase (portable bottles vs bulk delivery(.  If you run a portable genset on portable LP bottles, you will often be paying top dollar for the propane.  Buying 20# exchange bottles at  a Blue Rhino outlet, for example,  typically costs about $5.75/gallon. Many propane refillers charge $3.00-$3.99 per gallon, but others may be substantially less. Bulk delivery may well be down around $2.00/gal. to refull a large fixed tank.

Do the arithmetic for regular E10 gas vs propane in your area, but I'm betting the gasoline is the winner in most cases.  The advantage of propane is the convenience and safety of the enclosed tanks rather than cost of operation.
Title: Re: duo-fuel (LP and gas) gen's
Post by: Mark_K5LXP on May 29, 2019, 12:51:18 PM
The advantage of propane is the convenience and safety of the enclosed tanks rather than cost of operation.

And, the fuel doesn't get rancid over time like gasoline can.  You can store a propane genset "dry" along with a few bottles of propane nearly indefinitely.

Mark B.
Albuquerque, NM
Title: Re: duo-fuel (LP and gas) gen's
Post by: Gary RV_Wizard on May 29, 2019, 08:08:24 PM
Good point, Mark.
Title: Re: duo-fuel (LP and gas) gen's
Post by: daveinfv on February 08, 2020, 09:43:55 PM
Is it possible to run a dual fuel generator off the low pressure propane outlet on the side of the trailer for the grill? 
Title: Re: duo-fuel (LP and gas) gen's
Post by: John From Detroit on February 09, 2020, 05:22:27 AM
Generally.... NO
Title: Re: duo-fuel (LP and gas) gen's
Post by: ez3putt on February 09, 2020, 06:33:46 AM
Love my dual fuel generator.  It sits for months between uses and still starts up easily on propane every time.  No worries about adding stabil to the gas and running the carb dry when we shut it down, but gasoline is usually more readily available if I run out of propane.  Blue Rhino averages around $20.00 for an exchange and they only put 15 pounds in a tank.  The last time I got two empty tanks re-filled with 20 pounds each at Tractor Supply it cost less than $25.00 for both.
Title: Re: duo-fuel (LP and gas) gen's
Post by: Roy M on February 09, 2020, 11:01:32 AM
I learned to hate dual fuel, the gas would go skunky and STINK if not used up frequently and the propane dried out the carburetor bowl gasket. As soon as the machine was switched over gas leaked all over the engine. When it started giving trouble it was more cost effective to purchase a U.S. made lp only fuel system.
Title: Re: duo-fuel (LP and gas) gen's
Post by: Lynx0849 on February 10, 2020, 02:14:05 PM
I used to use a dual fuel generator as backup for the house. I had a 100gal propane tank and could run for days. It switched easily from gas to gasoline. Heck, you could do it running. Since I always seemed to have a few 5gal fuel cans around, during outages I would cycle them through the generator in daytime and get fresh later.

Actually I still have it and for sale. I now have an installed Generac. The old one was 9k watts on gasoline, 8k on propane & 7k on natural gas.
Title: Re: duo-fuel (LP and gas) gen's
Post by: Lou Schneider on February 10, 2020, 02:26:21 PM
I looked into a 2.5 Kw Generac portable dual fuel inverter generator for my sister's house last spring.  She telecommutes from her home office and is in one of PG&E's public safety shutdown areas where she could lose power for up to a week at a time during fire season.

What made me decide against the Generac (she got a gas powrred Honda EU3000i instead) was needing to use high pressure propane and an external shutoff valve to turn the propane feed on and off manually - if you just shut down the generator propane will continue to flow.  Too risky for a non-technical person to operate correctly, IMO.

The Honda is working out very well for her.  She's been through two week long power shutdowns so far.  She leaves it off overnight while sleeping, then fuels it before she starts it up in the morning.  It runs until she's done working for the day, then she shuts it down, refuels it and starts it again until she and my mom go to sleep at night.   It runs her home office, a swamp cooler, lights, the refrigerator, TV and other miscellaneous loads just fine.  Water is gravity fed from a spring further up the hill so she doesn't need a well pump.