How much propane should a generator use?

Fire Instructor wrote:

mlr1951 wrote:
How much propane should a diesel generator use?
A diesel generator shouldn't use any propane.

Sounded like a trick question to me, too!

How much dirt is in a 10' hole?

I understand that propane generators use more fuel but last time I bought propane it was around $2 a gallon. I have no idea what it is now. The OP said it cost him $70 to run the generator for 50 hours. That's about $1.40 an hour. My diesel generator is supposed to be burning about .5 gallons an hour under load. I've never checked it but I would guess if I had both AC's running it would be burning the .5 and hour. Diesel fuel right now is about $4 a gallon. So that means it cost me $2 an hour to run my generator versus the OP's $1.40 an hour.

How big is the generator? Fuel use is proportional to size and output.

4 KW generator at half load will burn about three pounds of fuel per hour, at full load about 5 1/2 pounds per hour. You can scale that up for other generator sizes.

20 gallons of LPG is about 82 pounds, so 50 hours does not seem unreasonable for running one A/C, which needs about 2 KW when running, somewhat more to start.

In bulk, LPG sells for about the same price per BTU as the liquid fuels. It should look like less per gallon than gas, if it doesn't have road use taxes, but often when filling a tank on any kind of motor vehicle the LPG distributor will charge the taxed price.

So cost to run a RV generator shouldn't vary much by fuel type. LPG, however, will likely be the least convenient to refuel.

Dog Trainer wrote:

ronfisherman wrote:
Propane generators use a lot of fuel. A diesel generator will use about 1/2 gallon per hour on about 1/2 load. My last run of 58 hours with my 5500 watt generator used 19 gallons of diesel.
On Onan's site they list 1/2 load amounts,
5500 LP .8 gallons per hour
5500 Gas .6 Gallons per hour
5500 Diesel .4 Gallons per hour
Owners with LP have looked at replacing the generator with a gas or diesel generator. Then found that it would cost $5,000 to $10,000 too replace it.

Hi Ron,
I will question the replacement cost of the LP to gas. would it not be as simple as changing the fuel line and the jets in the Carb. I was under the assumption that an LP was a gas engine modified to run Propane. I think the big problem would be to add a gas tank as most LP gen. are used on older diesels.

Could be on the LP to Gas. But with a diesel MH it would be better to look for a diesel generator. I have see some good EBAY deals on QD 6000 and 8000 generators lately.

FOR REFERENCE

Gasoline contains about 43.2 megajoules per kg (115,500 BTU/US gal)

The heating value of propane is 7% higher than gas at 46.4 MJ/kg however, due to its lower density, it has a 21% lower volumetric energy density (91,690 BTU per US gallon).

Diesel has a heating value of 43.1 MJ/kg, similar to gasoline, However, due to its even higher density, diesel offers an even higher volumetric energy density (128,700 BTU/US gal)

So, diesel's volumetric (by gallon) energy density is 11% more than gas, 40% more than propane.

I believe he said a diesel engine and a propane genny.

Propane is just a less efficient fuel than either gas or diesel. The Onan numbers quoted in an above quote look real. Changing the genny to diesel is a possibility but you can buy a lot of propane for the conversion cost.

If you got 50 hours on the generator with 20 gals. of propane, you did pretty good. Most propane generators will use about 3/4 gallon per hour.

ronfisherman wrote:
Propane generators use a lot of fuel. A diesel generator will use about 1/2 gallon per hour on about 1/2 load. My last run of 58 hours with my 5500 watt generator used 19 gallons of diesel.
On Onan's site they list 1/2 load amounts,
5500 LP .8 gallons per hour
5500 Gas .6 Gallons per hour
5500 Diesel .4 Gallons per hour
Owners with LP have looked at replacing the generator with a gas or diesel generator. Then found that it would cost $5,000 to $10,000 too replace it.

Hi Ron,
I will question the replacement cost of the LP to gas. would it not be as simple as changing the fuel line and the jets in the Carb. I was under the assumption that an LP was a gas engine modified to run Propane. I think the big problem would be to add a gas tank as most LP gen. are used on older diesels.

Propane generators use a lot of fuel. A diesel generator will use about 1/2 gallon per hour on about 1/2 load. My last run of 58 hours with my 5500 watt generator used 19 gallons of diesel.
On Onan's site they list 1/2 load amounts,
5500 LP .8 gallons per hour
5500 Gas .6 Gallons per hour
5500 Diesel .4 Gallons per hour
Owners with LP have looked at replacing the generator with a gas or diesel generator. Then found that it would cost $5,000 to $10,000 too replace it.

If your stovetop still lights, you are not out of propane. Your propane tank should have a visible level indicator, too.

If you have propane, the genset may have shut down due to low oil level.
Frequent oil level checks is a good habit.

You may have found the number one complaint with propane gensets.
Inconvenience of short tank life. It may be cheaper to stay in campgrounds with electric service.