Portable generator mounting in bay

[Nova Eona]

Hi all, looking for experiences and/or advice regarding mounting a portable generator in place of a genset.  I think I've got a handle on most of the hazards involved, including:

-Exhaust routing to clear chassis, seal compartment to ensure no CO infiltration to cabin
-Ambient heat buildup in compartment / fire risk, potential need for extra venting (squirrel cage fans?)
-Running generator while on wet, dusty, or bumpy roads, general abuse they're not really built for
-Special mounting required

The benefits as I see it are:

-Ability to use an inverter generator, much quieter and cleaner power
-Generator can be removed in the winter (New Englander here) and used as a house backup
-More options on sizing - I'm still sorting out my air conditioning, but I'd rather not oversize my generator too much
-Much cheaper than comparable gensets, even if it has to be replaced every few years
-Ability to pair with another non-mounted generator of same series when more power is needed


So I'm still in the plotting and considering stages, but I'm wondering if it would be worth experimenting with.  My 4104 has a large open bay (pic attached) which the previous owner kept a gas generator on a slide in, but I think he only used it when pulled out.  I'm replacing it either way so I don't have to carry three different fuels.  I'm not a full-timer, so I really don't need the duty cycle of an Onan either.

Who else has seen, tried, or seriously considered this?

[DoubleEagle]

It works if you are just using it while parked, but if you need power for two or three A/c's, it won't be enough unless you have a couple bigger Honda's that will cost thousands. Small gas generators won't last as long as diesels, and air cooled ones might not get enough airflow going down the road. A modest sized used diesel would be the wisest choice. You might not enjoy taking a portable generator out and putting it back every year, because it will need an exhaust hookup at the least. The bus generator can still be an emergency generator if it is closer to the house and the power cord is long enough. 

[Nova Eona]

Sadly the bus parks about 13 miles from the house, my extension cord doesn't quite reach!

I've been keeping an eye out, but even bunged up diesels still cost several thousand more than I'm hoping to drop on a generator right now - saw one on eBay today that had literally been on fire and they still wanted four grand for it!  Might go the route of putting in a compact propane Onan for road use and wiring the ACs individually so they could be switched to run off a portable inverter generator when stationary.

[DoubleEagle]

Well then, forget the extension cord,  but keep looking for used generators, they are out there. I recently bought a 17.9 Kw generator with a Turbocharged Yanmar Diesel (36 gross hp) with 2800 hrs. on it for $1,000 at an online estate auction. It weighs around 750 lbs, so you can't call it portable, but it will have a long life. Yanmar and Kubota Diesels are the most desirable, and then there are also Perkins Diesels which are also long lived, but don't seem to be as clean burning. I have four diesel generators at the moment ranging from under a thousand hours to over 19,000 hrs, but they all crank out the power. I might part with some someday, but I like to have spares. 

[neoneddy]

Well I'm on my 3rd generator now.  Started with a 4.0 Onan BFA, then on to a Harbor Freight 3500 Generator (the quiet one) , Now  with a 7 kw Onan .

I can say that you should use ½ of the rated watts as a base line, using  60-80% from time to time is ok, but don't expect to run that much all day.  So far I've been able to pull 3000-4000 watts from the new Onan all day with no issues.

As for mounting, I made a small slide out tray that works well, then I added some stress pads to the base to add some vibration isolation.

[buswarrior]

For weekend camper use, employing a less expensive portable, that is quiet, makes great economic sense.

You already know the life safety precautions about exhaust gases, get a CO detector from the box store for upstairs.

(EVERY coach should have a CO detector, to protect against infiltration from other sources than just your own coach!!!)

Put a good fan on the compartment, blowing OUT to defeat any unfound ways for it to leak into coach, used furnace squirrel cage fans move lots of air fairly quietly, and many have 2 speed motors.

Think really hard about how you will re-fuel, make it easy, consider you WILL spill some at some point, how easy will it be to clean that up safely...

Your ca$h, $pend it your way!

Happy coaching!
Buswarrior

[TomC]

Can't beat the longevity of a Diesel generator. I have a friend that had a 7.5kw 3 cylinder Kubota on his big rig that had over 23,000 hours on it when he sold the truck and still running well! Good Luck, TomC

[chessie4905]

Those Hondas last as long as the hours he'll put on it. And he can replace it 3 or 4 times for the cost of the diesel.

[dtcerrato]

Our old NH 6.5 kw Onan runs like a top since 1983. It's a slow turning (1800 rpm) gas & employs a high capacity vacu-cool system - moves a lot of air. It's a little noisy so am planing on solidifying the expanded metal compartment door it sits behind & force it to draw air indirectly farther away...

[DoubleEagle]

Our old NH 6.5 kw Onan runs like a top since 1983. It's a slow turning (1800 rpm) gas & employs a high capacity vacu-cool system - moves a lot of air. It's a little noisy so am planing on solidifying the expanded metal compartment door it sits behind & force it to draw air indirectly farther away...

I had an old Onan (that was old 25 years ago) in a RV that did great when I was parked, but when I was going down the road with the RV it would starve for air in the vacuum area by the grill. The faster I went and the hotter it was, the hotter it got, to the point of shutting off. I would recommend having an air scoop up front with tubing to feed the generator compartment if you want to close it off for noise control (or strong fans, or both).

[windtrader]

The optimal choice is influenced by the planned usage. You mention not full-timing but not much else about use: amount of power required and number of hours needed. The fewer hours you'll need it and the fewer watts you need to pull, it seems a smaller portable is the better choice. On the other hand, if you plan on spending weekends in the desert off grid, running the AC and other devices hours on end, a large diesel mounted unit is more likely to suit your needs.
Every fuel other than diesel requires more effort to refuel. Depending on how long you plan on running it between stops is a consideration; the more use between refills means larger gas storage onboard. At some point, it may make more sense to run the gen off diesel.
There are those here who do use gas gens for pretty heavy and regular use and are quite pleased with them, so both options are viable, you just need to see which solution fits you the best.

[Nova Eona]

Well, my planning wound up taking rather sudden shape thanks to a basement discovery/idea and a Craigslist find.  I managed to snag an Onan RV QG 3600 LP in great running condition for only $850 today, and found the pictured transfer switch where it had been sitting in the corner of my basement for the past five years ever since I moved in.

My plan now is to install the Onan to the left of the existing generator bay, making use of the open floor there and potentially a new vent or scoop for fresh air, thus freeing up the current mesh-walled generator bay to possibly have enough room to fit two mini-split condensers in the future, though it will likely get walled off as propane storage for now.  The transfer switch will become my new main breaker, with the awesome benefit of being able to manually select which circuits are on the generator or the plug - cool thing here is that if I'm out boondocking and need more power than the 3600 can put out or just want something quieter, I can fire up a second portable generator and manually split the circuits between them with the flick of a few switches, while keeping the Onan on duty for road use.

This should keep me happy for a long time I think - I can see myself investing in better insulation, solar, and battery banks much more than a diesel genny down the line, and for how cheap I got this generator I can buy a lot of propane with the savings already.

I'll record the installation and testing of this system when I get to it over on my project thread here: https://www.busconversionmagazine.com/forum/index.php?topic=34310.0

[Oonrahnjay]

Well, my planning wound up taking rather sudden shape thanks to a basement discovery/idea and a Craigslist find.  I managed to snag an Onan RV QG 3600 LP in great running condition for only $850 today,... 

      Sometimes, you hit a "forever" solution, and sometimes you hit a "for now" solution, and if you're lucky a "for now" solution turns into a good "forever" solution.   It sounds as if you have an excellent "for now" solution -- and that's a good thing.  Since you're just putting together the logic for your system, you can customize it to a lot of advantage.
      Congrats, I think you're onto a winner here.

[Jim Blackwood]

I think the propane generator has some advantages, particularly if you use propane for cooking, heating, refrigeration or hot water. Plus something I don't think I've seen mentioned here before, isn't propane sometimes used to boost diesel engine output temporarily, kinda along the lines of Nitrous for gas engines? It's relatively clean burning in the genny and less irritating to the neighbors.

Very nice transfer switch btw.

Jim

[neoneddy]

A worry I had with propane generators is the fuel availability.  I mean you can find gas or diesel most anywhere, but propane can be a bit tricky and if exchange is only allowed it can get expensive. It makes sense for a home where propane / natural gas is hard plumbed to the home for sure.