Converting a Generator to Propane

[JayArr]

Hi All

Our trailer is an early 90s Terry by Fleetwood, it's in good shape but only has a a pair of batteries with old school charger to power it. No inverter, no generator.

We love the government parks, the sites are larger and they tend to be nicer but they rarely have power so I get a little twitchy on day three of a long weekend concerning the battery bank level. In the spring and fall we need to run the furnace at night and I've now determined that we need a dehumidifier to keep the moisture down.

My solution is to add an inverter, I have a Xantrex Marine 1500 sitting on my shelf that a customer abandoned that I'll put to use. It should run everything but the AC and we're OK with that. The wife likes the idea of having the microwave all the time. If it turns out to be under-powered I also have some Freedom 458s in the 2000-2500W range I can swap in later.

The second stage is to add a generator so that we can recharge each day. Our Provincial parks allow windows of time for generators (9-noon, 5-7?) You can't run them all night.

I went and bought a Homelight 4000 portable generator on Craigslist. It's got the 8 HP Briggs and Stratton attached to a generator motor for 30 Amps at 120 or 15 at 240. It's also electric start so the wife can start it with the push of the button. I'm going to install it above the battery bank on the front tongue. (I have a mig welder so I'll make a frame for it). I should be able to just pull out the shore power cord, plug it into the genny and start it and let the Xantrex use the AC from the genny to recharge the batteries. I'm not going to wire the genny permanently, it has an outlet.

Now, as all ideas progress I started thinking of how to carry fuel for the genny and realized I have two forty pound propane cylinders right next to it so I found a propane conversion kit from US Carburetors for this model engine and it tees into the propane line from the trailer regulator. I'll pull the gasoline tank off and go propane.

Any flaws in my plan?

Has anyone done the propane conversion to a portable genny and mounted it permanently to their TT?

JayArr

 

[Mark_K5LXP]

If all you're doing is charging batteries you're smashing flies with a hammer with this generator.  You, and your neighbors are going to dread when you fire it off and have to listen to it hammering away for hours on end.  One of the small inverter gensets are more what you're looking for.  Some of the more popular models have propane refit kits.  You get a bit less power running propane but for charging batteries even a small inverter running propane would be more than enough.

Mark B.
Albuquerque, NM

 

[JayArr]

I'll go have a look.

The Xantrex charges at 75 Amps so with two 100Ah batteries less than 1/3 depleted I think I can get away with less than an hour.

I've seen 12V cigarette lighter outlets on generators before but didn't think there was enough power there to charge a deep cycle battery.

 

[skydivemark]

If all you're doing is charging batteries you're smashing flies with a hammer with this generator.  You, and your neighbors are going to dread when you fire it off and have to listen to it hammering away for hours on end.  One of the small inverter gensets are more what you're looking for.  Some of the more popular models have propane refit kits.  You get a bit less power running propane but for charging batteries even a small inverter running propane would be more than enough.

Mark B.
Albuquerque, NM

I agree. Inverter generators are much quieter and use much less gas possibly eliminating the need for the conversion to propane.
I know a couple people that have this model and both really like it.
https://www.harborfreight.com/2000-watt-super-quiet-inverter-generator-62523.html 

 

[JayArr]

OK, I cleared up how an inverter generator works, I thought maybe it made 12VDC that could be used to charge the batteries directly but it doesn't, it's 3 phase at higher voltages and then a double conversion. (AC - DC - AC). Kind of a waste of process considering I want to feed a Xantrex that will then convert AC - DC to charge the batteries. I'll end up with AC - DC - AC - DC. That's a whole lot of electronics and each stage has losses. I'll bet the manufacturers see the bright side that because the generator windings are small they are light and cost less to ship from China. Electronic inverters and converters are also a lot cheaper than copper windings.

There's a bunch of options, it seems the low priced ones in the $500 range can be hit or miss. Some of the reviews said a 2000W inverter wouldn't even run their microwave but others said it ran the AC. The Hondas have a stellar reputation but are priced in the $1000 range. Neither of these options runs on propane and neither of them has electric start.

For the $250Cdn I spent on Craigslist I'll stick with my good old "Made in the USA" Briggs and Stratton. I want my wife to be able to start the genny without a pull cord. If it's too loud I'll get a bigger muffler. But thanks, these have been good suggestions.

Has anyone done the conversion of a Briggs & Stratton to propane?

 

[blw2]

I'll suggest that since there's less energy per gallon of LP than there is per gallon of gasoline, that you'll be burning through propane a lot quicker.
And propane is harder to get filled and often more expensive.
I wouldn't do it.  Stick with gasoline

try cracking a window instead of running a dehumidifier... that'll save a bit of power

I'd look hard at a couple solar panels on the roof, larger battery bank...and you might be able to get through a long weekend with more batteries alone and skip the Genny all together.

I've got one similar to this that my dad found at a garage sale someplace.... I've only used it a time or two but it's not bad for an occasional need, and while not as quiet as the little honda clone (or Hondas), it's not nearly as loud as a big construction genny either.  Maybe good enough for an emergency top up for the last night if needed.

 

[JayArr]

Thanks BLW2

I'll take a look at solar as well, last time I looked they were only good for trickle charging. I'm didn't think I could get 800-900W from solar panels in one day but maybe they are getting better than the last time I looked. The rear of the trailer has no window so that's a possible place to put a couple of panels but they have to solve the whole problem, I'm not going to get solar panels and a genny.

The prices of gas and propane where I live are obviously different. I pay about $1.00 per gallon for LPG propane and almost $5 per gallon for gasoline. Even with the difference in energy of about 30% it's still 3-4 times cheaper to run propane than gasoline. Not that it matters much in small amounts like this. The main reason is that it will simplify things. I don't have to carry a gas can to refill the genny, I never have to winterize the genny, propane doesn't go bad if left unused all winter. Propane engines burn cleaner and last longer. and the big one... this genny is electric start so the wife can camp alone and still start it. There's no way I'm going to convince her to pull start a generator.

I've heard of cracking a window to let the moisture out, does this really work? We're in a 19 foot trailer with two dogs, if we open the window won't it just get cold causing the furnace to kick on which increases condensation?

 

[Mark_K5LXP]

The Xantrex charges at 75 Amps so with two 100Ah batteries less than 1/3 depleted I think I can get away with less than an hour.

If batteries were beer pitchers then that math works.  But batteries don't accept a charge linearly across their range.  An absorb phase is typically 3 hours, which is the last 20% of the charge.  If you don't care about restoring the last 20% then you don't need this recharge time but then you'll be running 20% shy of what your batteries are rated for.  So it will come down to what you use, and how much time you can invest bringing them back up every day.

I've seen 12V cigarette lighter outlets on generators before but didn't think there was enough power there to charge a deep cycle battery.

Not effectively anyway.  The AC side does the heavy lifting.  The generator you have will certainly work fine, but taming the noise will take a bit more than a bigger muffler.  Having it mounted right to the trailer means it would have to be nearly silent to not hear it running inside.  The big plus I see to propane is there are zero storage issues.  Stale gas turning to goo in idle generators is a big problem with RV's and propane solves that problem.  Whether you'll get the runtime you need with the tanks you have is a question you'll be able to answer after a few trips.

Solar can go a long way towards autonomy but it seems optimistic there in the Great White North.  All it takes is one cloudy day and you're running the genset anyway.  I'd want to run the camper for a while and have an idea of typical energy usage and determine feasibility before I'd start down that road.

Mark B.
Albuquerque, NM

 

[JayArr]

Hmmm, I forgot about that, I went and checked the manual and it charges at a constant current of 75A until the battery reaches 14.4V then it holds at a constant voltage of 14.4 volts until the current is below 10Amps and then it goes into float charge if/when the battery depletes to 13.5 volts.

I won't know until it's installed and I've run it how long it takes to get to a charge current of 10A at 14.4V.  I may have to settle for just the first stage of charge in order to keep the neighbors happy. Maybe I will need solar after all to finish the charge cycle after the genny shuts off.

I went and started looking at Solar after you mentioned it. There seems to be a lot of 100W panels at reasonable prices and some 250-400W panels at high prices. The trouble I've seen so far is they don't lend themselves to an existing lead acid system. The 350W units I looked at were in the 48V range and required a matching charge controller and a lithium ion battery pack. Fine if your designing from new but a bit of a pain when you have existing assets that would need to be wasted. I'll keep looking, inexpensive solar panels that easily hook up and compliment an existing 12V system would be my preference.

For noise... I'll put the super low tone muffler on and evaluate. If I have to I'll build a damper box around it to keep it quiet.

 

[Ex-Calif]

There are always naysayers and barn burners.

There are millions of people topping up batteries with generators.  Technically it does take "hours" to float charge a battery bank. But from 80-like 95 SoC a generator will work fine on a couple hours a day.  We liveabord boated and did 7 day crossings.

We would run the genny to make dinner - microwave - electric kettle and while we were at it would fire up the A/C to initially cool the cabin before bed time.  We had diesel on board and a diesel generator. The generator doesn't care what dinosaur fuel is spinning the shaft gas, diesel propane.

Different charging methods for different options. We had solar, wind, a generator and the on-board engine with 60 amp alternator. You can add solar later if boondocking is really a thing for you.

Do the propane conversion - it's a fuel you have on-board. Unless you are running out of propane in your "typical" period of boondocking you will be fine. My last fill of propane has lasted 9 months and about 30 days on board. I filled the RV gas tank probably 20 times in that period - plenty of opportunity to fill the propane if I needed to.

My only comment is to make sure you know what is going on with your tongue weight as I think you said you will mount this on the trailer tongue.

 

[Roy M]

The 'super lo tone' muffler will help but don't expect whisper quiet. A box around the generator won't help a lot, it still needs cool clean air to run properly and for cooling. The exhaust also has to be routed away from the unit.

 

[Lou Schneider]

I went and started looking at Solar after you mentioned it. There seems to be a lot of 100W panels at reasonable prices and some 250-400W panels at high prices. The trouble I've seen so far is they don't lend themselves to an existing lead acid system. The 350W units I looked at were in the 48V range and required a matching charge controller and a lithium ion battery pack. Fine if your designing from new but a bit of a pain when you have existing assets that would need to be wasted. I'll keep looking, inexpensive solar panels that easily hook up and compliment an existing 12V system would be my preference.

If you're looking for low cost solar, check out SanTan Solar in Phoenix.  They have a 250 watt system with one of their used 36 volt 250 watt panels and a MPPT controller to convert the  output to 12 volts for $250.  The panel was removed from a stationary application when the tax credits ran out and still has plenty of life left.  Additional 250 watt panels are $50 each.

It's best if you can do local pickup as shipping solar panels are expensive due to their physical size.

 

[X-Roughneck]

There are always naysayers and barn burners.

We live aboard a boat and did 7 day crossings.

Dan,

Ocean Crossings?  Sounds Like an Epic Adventure, Plural x 7. 

I would have had the Jaws Sound Track Playing in my head and that would have prevented any enjoyment for me.  ;D

Had to get that slightly off topic reply in there, sorry.

JD

 

[Rob&Deryl]

Last I checked, dehumidifiers draw a lot of power.

There was a thread here a few weeks ago with a dream of running the microwave, the furnace and some lights on batteries and it was going to take lots of battery power (and then lots of charging time) to run the microwave for a few minutes and the furnace overnight. Microwaves and dehumidifiers are not good candidate for battery power.

Adding plenty of solar (more than a simple 100w panel) will help.

 

[JayArr]

Thanks All

The provincial campsite we were at for Thanksgiving weekend had dozens of people charging batteries with their generators, once breakfast was over and everyone was awake it seemed OK to fire them up and get your charge back. Some were louder than others. Maybe it's the climate up here or maybe it's the initial cost but I only saw a handful of people with solar panels.

Propane use - there are two 40 pound tanks on the trailer. we used one and a half on our summer trip and we were gone a month. That'll change with winter camping but I still think the generators portion will be minimal.

I'm a little light on the tongue weight right now because I have the load proportioning bars on my hitch, the extra 100 lbs should be no problem.

 

[CharlesinGA]

Hi AllI went and bought a Homelight 4000 portable generator on Craigslist. It's got the 8 HP Briggs and Stratton attached to a generator motor for 30 Amps at 120 or 15 at 240. It's also electric start so the wife can start it with the push of the button. I'm going to install it above the battery bank on the front tongue. (I have a mig welder so I'll make a frame for it). I should be able to just pull out the shore power cord, plug it into the genny and start it and let the Xantrex use the AC from the genny to recharge the batteries. I'm not going to wire the genny permanently, it has an outlet.

JayArr

Basically, you bought what is referred to as a "construction" or "open frame" generator. Some campgrounds may not allow this type of generator, some don't care, but your neighbors will hate you. This is a Youtube video (starts at 2:31 into it, but I suggest you go back and watch the whole thing) https://youtu.be/MAMEPljcN0E?t=151 This will give you a good idea what your generator will sound like to your neighbors. The video is on Campground Etiquette, by Long Long Honeymoon, the longest running, oldest RV Youtube channel which started about 13 years ago.

The 240 volt capability will do you no good for camping either, and with this generator you will need an adapter to tap off of ONE SIDE of the 240 volt, giving you 120v, for the trailer shore power. If the generator has a three prong plug that resembles the shore plug but not quite, it is a 240 volt three prong found on some generators and you will destroy the trailers electrics should you hook directly to this plug. Also, mounting the generator on the tongue of the trailer will vibrate the daylights out of the trailer, making it very uncomfortable inside when it is running. The best thing you can do is relist it on Craigslist and then find an inverter generator. Look for specifications of no more than 60db, which is the National Park Systems maximum limit for generator noise level.

Are you sure you have 40 lb propane bottles, they are rather unusual on travel trailers. 20 lb is the common BBQ grill bottle and used on many travel trailers, and 30 lb is the common alternative. A 40 lb bottle is just over 29 inches tall, a 30 lb bottle is 23 inches tall, and a 20 lb bottle is 18 inches high.

Inverter generators work well because they do not need to run at a constant 3600 rpm to maintain 60 hz. Instead they run at a slower speed and make only the current that is demanded by the user with the inverter handling the stability of the 60 hz and 120v. You will find that an inverter generator is more pleasant to use and much quieter and provides the power you need.

Charles

 

[Roy M]

I am a retired small engine mechanic, propane conversions on these are a pain in the butt. Fuel consumption is up, power is down. Conversions never work well. As suggested you will be much happier with a quality inverter unit such as Honda or Yamaha. Yes they are more expensive up front but with a little care will give you years of service. IMHO, the Chinesium knockoffs are a waste of money although some are happy with them.

 

[JayArr]

Hi Roy

Do you have any experience with US Carburetors? The kit I bought involves inserting a propane jet in the carb at the point that the old gasoline jet was located. You actually modify the carb by drilling one port larger to accept the new propane fitting and sealing the other ports off. When your done the carb can't be used for gasoline anymore. They say it's far better than the type that bolts on.

Which types of conversions have you done?

 

[skydivemark]

Wow, drilling holes in a carburetor and permanently sealing others?
Definitely NOT something I would even think about or attempt on a good operational unit. Basically it sounds like if anything goes wrong, the generator is scrap metal and another generator will be on the shopping list, maybe 2 if you need the original one for home use &/or power outages, another reason to not convert it.
I understand you want your wife to be able to start it by push button, understandable, but camping (especially boondocking) does come with a few inconveniences and pull starting a generator once or twice a day is a very small one - IMO.
Inverter generators are much easier to pull start than open frame gen-sets. My friends wife starts theirs frequently and says it's very easy and also says she usually gets it on the first try (theirs is the harbor freight model and they've had it a few years).

 

[Rob&Deryl]

The 240 volt capability will do you no good for camping either, and with this generator you will need an adapter to tap off of ONE SIDE of the 240 volt, giving you 120v, for the trailer shore power. If the generator has a three prong plug that resembles the shore plug but not quite, it is a 240 volt three prong found on some generators and you will destroy the trailers electrics should you hook directly to this plug. Also, mounting the generator on the tongue of the trailer will vibrate the daylights out of the trailer, making it very uncomfortable inside when it is running. The best thing you can do is relist it on Craigslist and then find an inverter generator. Look for specifications of no more than 60db, which is the National Park Systems maximum limit for generator noise level.

Charles

I have had open frame generators that had NEMA 5-30 connectors on them which, with an adapter, is fine for a 30a trailer.

You are correct in that some construction generators may have a 10-50 on it for a welder but I have never seen the 30a version, 10-30, on a generator since it isn?t enough amps for most brute force welders. The 10 series is 240v but without a neutral.

To the OP, always check the NEMA number on any connector prior to use and be sure you use the correct adapters.