# Generator - Gas or Propane?



## tarbe (Apr 7, 2007)

This isn't really alternative energy...but this is where the folks hang out who can discuss this!

We are putting a 27 foot camper on our property in MO in a couple weeks. 

I want to put some solar up to keep a battery bank charged...but in the short term, I will use a generator (property is off-grid and about a $10k charge to get electrons to it!).

I am researching portable generators. RV shop says get one rated to at least 4,500 watts if I plan to ever use the a/c (I do!).

I love diesel power plants and have two diesel vehicles, but the diesel generators I've seen are so much more expensive I have dismissed them for the time being.

I am intrigued by the propane units. I really like the idea of not pouring/spilling gas, not dealing with ethanol in the fuel and having to treat for it, not worrying about the gas going bad between trips up, etc.

Who has experience with both gas and propane gen sets and would be willing to opine??

thanks!


Tim


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## Molly Mckee (Jul 8, 2006)

Our generator runs on either gas or propane, we like it well enough that our son-in-law and nephew bought one as well.


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## tarbe (Apr 7, 2007)

Molly Mckee said:


> Our generator runs on either gas or propane, we like it well enough that our son-in-law and nephew bought one as well.


Do you have a preference for one fuel over the other?

Thanks,


Tim


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## Molly Mckee (Jul 8, 2006)

We have used gas, because it's easier for short term use. The gas is right near the generator and my DH hasn't run the LP line to it. He is planning to do that soon, so we'll know soon which we like better.


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## Jim-mi (May 15, 2002)

There is no question which is better . . . propane means a far cleaner running engine.. .longer oil change intervals, no carbon build up . . .

A "tri fuel" setup is nice.........


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## oldasrocks (Oct 27, 2006)

We have a full house 15KW genny that runs on propane. During the ice storm a few yrs ago it ran flawlessly for 11 days. I prefer propane as the fuel doesn't go bad and you don't have to fight the weather to refuel it.

We have a 2nd 15KW gas to run the well and shop. Its supposed to be run for awhile every month to keep it in shape. That unfortunately doesn't happen. I do keep a trickle charger on it. Gas units take more maintenance.

We looked into a smaller unit to just run the frig and freezers to save fuel but find they do not have a great lifespan. They are made to use on occasional weekends for a camper or something.


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## tarbe (Apr 7, 2007)

oldasrocks said:


> We looked into a smaller unit to just run the frig and freezers to save fuel but find they do not have a great lifespan. They are made to use on occasional weekends for a camper or something.


By smaller, are you saying a sub-3000 watt...or sub-5000 watt or???

I want to be able to run a well pump, and a camper a/c (not necessarily at the same time) and want to be able to top off my eventual battery bank.

Thinking I should get something at least 5 or 6,000 watts. Seems like you can get a 7-8,000 watt propane for less than $1k.


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## oldasrocks (Oct 27, 2006)

By smaller I mean 5,000 or less. I tried to run my well with a 7,000 watt unit but it was too small. Our well is deep, 300 ft plus on 220 and 30 amps.


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## tarbe (Apr 7, 2007)

oldasrocks said:


> By smaller I mean 5,000 or less. I tried to run my well with a 7,000 watt unit but it was too small. Our well is deep, 300 ft plus on 220 and 30 amps.


Sounds like if you wanted to run that well pump at half power, you'd need about 12kw?

Pumping that heavy water against gravity takes a lot of power!


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## ct01r (Jan 21, 2014)

We currently have a portable 7500w generator that's gas. From everything I've read and heard from installers, propane is the way to go. Besides the fuel not going bad and lower maintenance costs, they're a lot quieter. If we ever upgrade to get one for the whole house, it'll be propane. Curt


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## Esteban29304 (Apr 29, 2003)

Be sure to check with suppliers for the price of propane. It varies A LOT in different areas.


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## oldasrocks (Oct 27, 2006)

Good point Esteban. Remember to fill during the off season too. Everyone was robbed last winter with the supposed shortage.


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## farminghandyman (Mar 4, 2005)

I have three generators, 
two of them set up to use propane, a 20kw and a 4kw, unit, I like propane for the units, I have a 1000 gallon tank that supplies them, (besides exercising them and one short outage,) the tank has been full for over 10 years now, 

great for long term storage, 

the other generator is a welder/generator, and it is gasoline, and on the back of the pickup, a 10,000 watt unit, it is gasoline and it is fine as it is used often, the gas does not go bad, 

before propane I bet I lost more gas to evaporation than ever used, 

propane there is no tax on it (road tax) here, the price is lower than gasoline, 

propane you may have to derate your unit a little, (less BTU per gallon).

one problem I see, (running a generator is expensive, regardless the fuel you use, 

running a tank full through, and having to go fill it will remind you on the cost and help you evaluate if it is needed, 
if hooked up to a large tank (gas or propane) you have sticker shock getting the tank refilled, 

you talked about solar and charging batteries, one could consider a small engine generator running a generator that would charge your battery bank, 24 volt alternators are used on some heavy equipment, so should be fairly easy to set up, 

(one may still want a regular generator, for "more power") or well.

I have read that many of the smaller generators do a poor job of operating a battery charger to charge a battery bank, 

if your in to diesel on cars, I would take another look at that, for the economy of it, for the generator put in a 300 gallon farm tank and call a fuel supplier and get off road diesel no road tax, dyed red, instead of clear taxed diesel,

I you do use gasoline talk to your supplier you may be able to get some paper work to send in for a tax refund, for off road use, (more complicated but you may be able to get your tax money or some of it back,


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## tarbe (Apr 7, 2007)

farminghandyman said:


> propane you may have to derate your unit a little, (less BTU per gallon).
> 
> one problem I see, (running a generator is expensive, regardless the fuel you use,


I have seen several dual-fuel generators that specifically label them with two wattage ratings, one for gas and one (about 15% lower) for propane.

Yes...for sure...electricity produced by a portable generator running on grid gasoline or propane is expensive! Done in a big way on a regular basis would be a quick way to go broke!

Thanks for the reality check!


Tim


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## oldasrocks (Oct 27, 2006)

I don't think most people plan on running a genny 24/7. We had to during the ice storm as the furnance would not run without juice. Since then I installed a gas stove in the living room. Thermostat controlled by battery.

We figure on running the genny about 2 hrs a day, enough for laundry and showers. With heating with above stove we have enough propane for 8 months though a winter.


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## fordy (Sep 13, 2003)

...............Several factors I'd be concerned with 1)Look into purchasing a unit that runs at ~1800 rpm and is water cooled ! As such engine lasts longer because of stable operating temp environment . Any engine running at lower RPM will have a longer service life than one running at 3,600 rpm . All engine's running @1,800 rpm will require larger displacement because most small engines up to about 26 hp don't achieve max torque until ~3600 rpm . This is probably true for engines larger than 26 hp as well . This why most gensets , today , run at 3600 rpm . 
................As far as diesels , I'd look for a Turbo charged model , but they usually don't Tc small diesels until the 30kw range . , fordy


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## Nimrod (Jun 8, 2010)

You can take a gasoline generator and adapt it to run on propane or natural gas. Google "generator propane conversion" and you will find several companies selling conversion kits. There is also instructions from a guy who modified an old carb to run on propane. He has to switch back to the original carb if he wants to run on gasoline.


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## tarbe (Apr 7, 2007)

fordy said:


> ...............Several factors I'd be concerned with 1)Look into purchasing a unit that runs at ~1800 rpm and is water cooled !


I am not looking at anything over 10k watts. All the smaller units I've seen (say 17hp and below) are air cooled and run at 3,600 rpm. I suspect if anyone made a 10k watt or lower with a water-cooled engine, the cost would be enough higher that you could buy multiple air-cooled engines?

One thing I do like about the larger/more powerful engines is some of them have pressurized oiling systems vs splash. 

What about units that have automatic idle-down? Seems like that would save wear and cut noise and fuel consumption.


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## fordy (Sep 13, 2003)

http://www.generatorsales.com/

..................Have a look at their inventory , they have a 10kw model with a Honda engine running at ~1800 rpm ! , fordy


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## fordy (Sep 13, 2003)

...........Automatic idle up and idle down features on gensets seem to be getting harder to find ! Most welders have them , but Honda includes them on their inverter models , where they are load sensing and increases the RPM to match the load and will decrease RPM as the load goes down . , fordy


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## bigjon (Oct 2, 2013)

had a 5500 gas units for a couple years(trotbult).run everything but ac.2yrs ago I purchased a used generac 8000 guardian.propane-runs 15mins every week to keep battery charged.best part-rain snow ice storms etc-i don't have to go out.i don't even have to be home.capacity-runs EVERYTHING,freezers-micro-garage-well heat.best investment I've ever made.


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## Gray Wolf (Jan 25, 2013)

Start with the starting loads of any electric motors you'll be running. 

Start with the starting load of your ac.

Start with any equipment, like welders.

Start with the requirements of the battery charger for your battery bank.

Don't oversize too much or you'll just waste fuel.

In our case:

Our 220 volt well pump lifts just a bit over 700' and needs at least 8,500 watts to start.

The 40 amp 24-volt battery charger for the 16 batteries powering our off-grid home needs at least 2,000 watts.

My 220 volt welders are happy with 8,500 watts as long as I don't go crazy with the duty cycle.

Over time, I figure it's cheaper to have a few generators and use the smallest/cheapest/most fuel efficient one for the task. 
My 10,000 twin is a gas hog for welding and backup. 
My 8,500 one gets used for pumping water once a week. 
My 3,500 watt one gets run for battery charging. 
And, I have a 2,000 watt one for camping and as a backup for battery charging.

Our only diesel engine is the tractor.

If you want auto-start or remote start, go propane.


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## farminghandyman (Mar 4, 2005)

tarbe said:


> What about units that have automatic idle-down? Seems like that would save wear and cut noise and fuel consumption.


 I would not consider a automatic idle down, 
it take very little more fuel to fast idle the generator (no load), 

the second is it is very hard on equipment,
and would most likely destroy most electronics, 

when one idles down the cycles are reduced, and the voltage many be compromised as well, any thing starting under load has a defiant disadvantage, (my welder /generator has a idle down) I had a small air compressor on the truck one day it keep snapping the over load on the compressor motor, when using a chop saw on the welding truck it is hard on the saw, I now click off the auto idle, even welding it is a pain in the lower end, 

my folks had a generator after WW2 that had a sensor and would auto start when power was needed and would shut down when the power was shut off, 

my mother said when they would turn on a switch it would take about 15 seconds and the light would come on, 

I have looked for a auto on and off system and have not been able to find one, 

I could see advantages to that system, 

~~~~~~~~~~~~~~~~~~

as far as the generator to propane both of mine have been conversions, (the large one 30 kw), I used a fork lift kit, 
the small I ordered off the net form a place that specilized in the kits, 

~~~~~~~~~~~~~~~~~~

but I would think that for the most economical system would be to have batteries and an inverter, for low power usage and use and at night, use the generator to charge the batteries and to do heavy power needs, 

one other advantage to a water cooled unit, is the possibility of CO GENERATION, that is to use the hot water created to do laundry baths and other with the same fuel that generator the power, the heat would have been wasted any way, 

one other idea with the Cogeneration is the possibly of heat or supmental heat in the dwelling. using the waste heat, of the engine,


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## farminghandyman (Mar 4, 2005)

when I was converting the generators to LP, I considered the idea of a remote car starter, as my generator shed is some distance away from the house, this was during the Y2k concern, but it would have saved many steps.


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## tarbe (Apr 7, 2007)

fordy said:


> http://www.generatorsales.com/
> 
> ..................Have a look at their inventory , they have a 10kw model with a Honda engine running at ~1800 rpm ! , fordy


Wow, they have an amazing selection. Lots of gen sets I have never seen while googling.

Thanks!


Tim


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## jimbo913 (Jun 18, 2015)

I have had all 3 types. Started with 3600rpm gas 6000/7500surge, then 3600rpm diesel 5000/6500surge) then 1800rpm water-cooled propane 12kw, then 1800rpm diesel 10kw (rated 12kw but can run 15kw for 20mins).

My purchase decisions were all based on cost but I eventually ended up with what I originally wanted which was diesel. Luckily I take care of my stuff or improve it so I didnt lose much to get to my final goal vs buying the diesel from the start.
I still have the 3600rpm diesel with under 40hrs that I plan to sell.

Gas - Loud and fuel goes bad quick plus is more flammable than diesel. Can gun up carbs quick while sitting. Inverter types can be quite but cost $$.

Propane units typically have enclosures so are often quite but are fuel hogs. At up to 2 gal per hour rated load you could easy spend $100 per day to run so would be better off getting a hotel room. If only using for 1hr a day to charge a battery bank, a 1800rpm unit should be reliable and long lasting.

Diesels are built heavy to withstand high compression. These units have no plugs, wires, distributors or ignitions to fail. The fuel will not ignite by match and lasts for years. Fuel is easy to transport yourself without relying on propane truck which would not go up my gravel drive in winter.
Fuel consumption on my large military diesel is .9gph full load.

Hope it helps. If you do not need quite or can build a shelter look for a low hour rebuilt mep-003 or mep-002 military generator. These are rated at 80% capacity at 4000' and 120f.


Propane -


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## JeepHammer (May 12, 2015)

Long time engine builder,
And long time off grid, about 13 years.

*IF* an engine is built for propane/natural gas, it will run fine on gasoline if you 'Dual Fuel' the unit.

A 'Gasoline' engine that was converted over to propane won't have the longest life span.
LP and CNG are corrosive, stuff like stainless steel valves and valve seats, and some other small changes will make the unit live much longer no matter what fuel you pump through it.

It's easy enough to 'Dual Fuel', I do it myself, a DIESEL generator/welder converted to propane,
And a Farm Jeep that burns gasoline or propane.

-------

Propane over Liquid fuels is preferable, since propane/CNG stores indefinitely without decomposition.
Both Gas and Diesel will need 'Treatment' to keep their BTU energy past about 30 days, and no commonly available additives will keep either from lasting must past 90 days without degradation.

Diesel is about worthless past 90 days,
While most gasoline will be down to about 1/2 the BTUs at the 90 day mark.
Preservatives will help with this, but it's going to happen no matter what you do to the fuel.

There is also the issue of bacterial growth in diesel fuel, which will cause serious issues with diesel fuel filters, pumps, injectors.

Propane, while corrosive, is pressurized and doesn't grow microbes, and it stays DRY in this pressurized form, it doesn't draw moisture like liquid fossil fuels do.

-------

Some recommendations,
I use industrial (fork lift) couplers for the fuel tanks on the lines.
If the 'Big' tank runs dry,
The little 'Grill' (20 lbs), or travel trailer (30 & 40 lbs) or fork truck tanks can be hooked on to the generator with little or no problem for 'Back Up' until you get the big tank filled...

Hard plumbed lines without quick threaded connectors don't allow for 'Spot Use' of smaller tanks.

When you fill smaller tanks,
Find a propane fill station and watch the scale yourself when the tank is being filled.
It's common practice for the 'Tank Exchange' places to only put 13 or 15 lbs. in a 20 lbs. grill tank,
While the propane dealers will usually give you a full 20 lbs for the same price as the exchange tank places, and sometimes they are cheaper.

Most propane supply places will provide a large above ground tank for little or no charge if you buy propane from them exclusively.

If you order an underground tank (out of sight of vandals) you will usually have to buy that tank or pay an installation fee along with a rental fee.

Buy your propane/CNG in the summer when it's MUCH cheaper.
Some places will allow you to purchase in the summer, and not deliver it until you need it...
This is a TREMEDOUS service and cost savings over 'In Season' pricing.

Watch for industrial places, especially warehouses going out of business and selling off the hardware.
It doesn't happen often, but you can get the big, heavy duty propane tanks for Fork Trucks for dirt cheap!
They are re-buildable (Valves/Gauges) and re-certifiable, where the grill and travel trailer tanks are not re-certifiable, after about 10 years no one will refill them.

Buying a coupler that has a plastic body or plastic threaded knob is a waste of time and money.
It's better to buy the big, industrial brass units, they live indefinitely.
I have some that are 30 years old and still working like a champ.

If you run hard lines from tank to generator, grill, home, whatever, use Stainless Steel.
Well worth the money over plain copper tubing (Illegal, but people do it anyway) or the plain steel with the yellow vinyl coating.
Stainless will last your lifetime and not fail, and doesn't cost much more than copper or the plain steel line with vinyl coating...

If you do 'Dual Fuel', use an ELECTRIC fuel pump, So you can switch the electric fuel off!
You DO NOT want to work a MECHANICAL fuel pump dry! The pump WILL fail.
An electric pump will allow you turn simply turn the liquid fuel 'Off' and run the propane when you want to without issues in the liquid fuel system.

I run my liquid fuel systems dry before storage.
This keeps the fuel from 'Rotting' over the time the equipment is in storage.
If I need to fire up for short periods, I simply use propane...


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## JeepHammer (May 12, 2015)

As for generators,
Look around for Insurance sales lots, or RV salvage yards.
You will usually find large, LOW RPM generators for cheap in those places.

If you intend to run a high RPM engine generator, it will drill into your brain listening to it run,
But the larger, low RPM generators won't do that to you.

I have two large 7,500 Watt, 10,000 Watt, Onan low RPM generators I used before I got the big welder/generator,
Both were from RV's, and both VERY cheap to buy and operate.

This is a particularly good way to acquire a DIESEL generator on a budget.
The big diesel pusher RVs have large diesel gensets installed, and they get totaled all the time...

A diesel genset is VERY easy to convert over to Proapne, the kit is about $350 and is bullet proof from Onan and other suppliers.


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## Darren (May 10, 2002)

JeepHammer said:


> Long time engine builder,
> And long time off grid, about 13 years.
> 
> *IF* an engine is built for propane/natural gas, it will run fine on gasoline if you 'Dual Fuel' the unit.
> ...


I used diesel/heating oil that was several years old when I got it. This was in the North where algae is not as common as in the South. Diesel, kerosene and heating oil are oils. They can be stored much longer than gasoline. The fuel oil I got was at least five years old and was stored in a 2,000 gal. tank that was vented to the atmosphere.

PRI D for diesel or PRI G for gasoline can be used to store the appropriate fuel for years. They're better than Stabil and go farther per quantity treated per container.


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## beenaround (Mar 2, 2015)

oldasrocks said:


> I prefer propane as the fuel doesn't go bad .


number 1 reason right there. Doesn't take gas more than a month to start going bad. Propane never goes bad as far as I know. 

Propane isn't regulated and therefor your at the mercy of the dealer for service and cost. really bugs me and I shy away from anything that uses that fuel. However, when it comes to back up power and the need for the fuel to sit for long periods I don't think propane has an equal.

People who have them professionally setup also have them setup up to run on a regular basis so they are up to the job when they are needed. One place my brother hunted he always knew when it was 4:30, ran for 10 minutes.


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## jimbo913 (Jun 18, 2015)

I too have used years old diesel with no problems. Gas is a different story these days.

Propane engines require spark plugs and wires which can go bad or wires get chewed on.

I prefer diesel stored in several drums vs relying on a 500 or 1000 gal propane tank which could leak all its contents without me knowing. Not to mention when shtf I can find alternative fuels to power my diesel.


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## JeepHammer (May 12, 2015)

*IF* there was some catastrophic break in the supply chain of fuel,
Then a 'Duel Fuel' or 'Multi-Fuel' unit would be the way to go.

I got a screaming good deal on my big generator, it was gasoline.
For $350 it's Dual Fuel, both Gasoline and Propane.
With spark plugs, it could also be Alcohol, which I can make myself if I absolutely had to.

A diesel unit would cost the same for Diesel and Propane,
Again, propane unit added above the carb will cost you about $350 on a large generator.

And a diesel unit will run on about anything you can dump into the tank that will combust.
Perfume, Alcohol, So called 'Diesel' units aren't picky, about anything that will combust under compression will fire up,
The unit might be a little hard to start, and horsepower output will vary, but they will burn about anything.

It's not particularly what you have, it's what you do with it...
My Diesel Generator is also a welding machine...
When I fire up to weld, the well pump runs, the batteries get charged, and a few other things happen since there is power being produced that would otherwise go to waste.

When the much smaller Gas/Propane generator fires up, it also runs the well pump, charges the batteries, and powers the home all at the same time.

It's no big mystery here,
It's just power being produced...
With some wiring/switches you can make that power do anything you want...

With Propane, the fuel is dry, doesn't loose BTU's, and will store indefinitely.
If you buy in the summer, it's MUCH CHEAPER per BTU than Gasoline or Diesel,
Even with the current low liquid fuel prices...

Gasoline and Diesel WILL NOT store indefinitely, they have a FININTE life span,
Especially when stored where they are vented to common atmosphere.
Environmentally sealed containers for liquid fuels is VERY hard to do *PROPERLY*, 
They have to be temperature stabilized, they have to have expansion room, they have to be nitrogen or other inert gas stabilized...

IMPROPER storage, but still sealed, will extend the lifespan of some liquid fuels,
But it's IMPROPER, and a hazard...
I find that Propane is VERY easy to store, very easy to use, and very clean when I use it, 
Maintenance cycles are MUCH farther apart when using propane than when using liquid fuels.
Again, this saves me money in the long run, less filter changes, less oil changes, ect.

*It's up to the individual person on what they choose, their mechanical abilities, and their budgets.
Go with what you are comfortable with and what is in your ability comfort zone.*


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## nosqrls (Jun 9, 2012)

You should see how the navy stores diesel fuel on board subs for years. Tanks are pressurized with sea water to 15 psi no air in tank, diesel is taken off the top. They store up to 38000 gals. for 2yrs or more.


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