Onan 7500QD in front storage compartment? Am I delusional?

[immortl]

Hey folks, new member here, first post. I've been hanging out over at irv2 for a few months now, recently discovered this Keystone specific forum.

We recently purchased a 2016 Keystone Alpine 3900RE. It has the small side load garage in the back for the wife's Harley and will be my office when we're parked. In an effort to accommodate some boondocking and to provide enough power for 2 ACs, my computer gear (network security engineer, would like a small lab of hardware with me) we would like to see if we can finagle an Onan 7500QD into the RV. I also like the idea of a diesel generator as the truck runs on diesel, so one type of fuel to stock up on and carry with. Less volatile too, shouldn't be an issue to add a diesel fuel tank to the fifth wheel, DOT rules and all that.

We'll be at the trailer in a month or so and I'm doing some research ahead of time. Based on measurements, I think there is enough space to wrestle the generator into the front storage compartment. That said, it won't necessarily be easy as it weighs about 420lbs. Has anyone put such a generator into the front storage before? Did some searching, but haven't come up with much yet beyond the 5500 series ones. I am thinking some extra steel supports might have to be welded in under it? The fifth wheel currently has 2 12v batteries, I'm thinking I will replace them with a LiFePO4 or two, to make up for a little of the extra weight of the generator, but it's still quite a bit heavier than the traditional gas models I've seen in that compartment. I also have a sense that being able to slide the generator out for maintenance access is important. Seems like it might be challenging to rig up a slide/rails that would support the 420lb weight.



We like the idea of something onboard, press a button and we have power. Wife may be solo at times (I travel some for work) so having to set up multiple external generators or a single larger and heavy portable is less than desirable.



If the generator fits, I'll use a fuel cell from someplace like Summit Racing for a fuel tank. Again, based on initial measurements, seems like I could fit a 16 or 20g fuel cell along side the generator, maybe. Otherwise I'll see where else I could fit one when I'm at the trailer.



What say you? Possible? No way that'll work? Any suggestions, look out for X, you forgot about Y?


Thanks,
Joe

[wiredgeorge]

A generator under the bedroom seems like a bad idea as the area wasn't built to house a generator and thus isn't sealed. Most generators require space around them with a lot of ventilation. You will also hear the thing at night when sleeping. Not sure enough bracing could be done up there to safely support over 400 lbs of weight. I am sure folks have done this and perhaps they will chime in but haven't heard of that large a generator in the front storage and it would compete with the landing gear and batteries as well for that space. Last thought... 15K gross weight trailer. Usual pin weight is about 23 percent so you are looking at almost 3500 pin weight. Add 400 plus pounds of generator.... plus passengers and stuff in the truck and hitch. You are putting a lot of weight on your pin. What is your truck's payload? It may not be up to snuff.

[immortl]

Payload on the truck is 4689 lbs, according to door jam sticker. 23% of 15.5k is 3585, let's add in the full 420 of the generator, gives 4005 pin weight. Getting close once you add in wife and I (say 290lbs between us). Seems manageable to stay under without too much paring down, but I prefer to run under limits, not right at.



I was wondering about generators under the bedroom too. But it seems most fifth wheels with onboard generators put them in that front compartment, at least all the ones I've seen in person and in pictures. I sort of figured that was where they went. It may actually be easier to put it on the left side of the pass through where some of it is blocked already, but then we could only really access the no longer pass through from the right side. We both like some background noise/drone and use sound sleepers white noise machines when sleeping. I think I'd be ok with generator drone, not sure about the wife. She's had a toy hauler in the past before meeting me, I'll ask her how she did with generator running at night under her.


Thanks,
Joe

[notanlines]

Did yours come with genprep?

[immortl]

I believe it did. I'm not at the trailer currently, but have someone checking for me. I'm not sure what that all entails though. Looking at pics of the front storage, there is nothing obvious jumping out at me though.



Thanks,
Joe

[jasin1]

Unless it has the generator prep I’d probably get a really nice portable generator and leave it in the back of your pickup..get a long shore power cord and go with that..you can even combine two smaller generators,that way if you don’t need the ac units running you could use just the one. Chain it to your fifth wheel hitch and get a cover for it

[wiredgeorge]

Originally Posted by jasin1

Unless it has the generator prep I’d probably get a really nice portable generator and leave it in the back of your pickup..get a long shore power cord and go with that..you can even combine two smaller generators,that way if you don’t need the ac units running you could use just the one. Chain it to your fifth wheel hitch and get a cover for it

You would have to rig some sort of cover for a bed located generator because you wouldn't want to run a generator in the rain... sounds like payload won't be an issue and if you have "gen prep" this might make the project do-able. Generator prepared will mean they already have some sort of insulated and ventilated box for a generator. I haven't heard about one with as much wattage as you are thinking about so dimensions would be an issue. Most generators are in the 5K watts range they stick in campers and under 300 lbs as a guess...

[Javi]

Originally Posted by wiredgeorge

You would have to rig some sort of cover for a bed located generator because you wouldn't want to run a generator in the rain... sounds like payload won't be an issue and if you have "gen prep" this might make the project do-able. Generator prepared will mean they already have some sort of insulated and ventilated box for a generator. I haven't heard about one with as much wattage as you are thinking about so dimensions would be an issue. Most generators are in the 5K watts range they stick in campers and under 300 lbs as a guess...

Originally Posted by jasin1

Unless it has the generator prep I’d probably get a really nice portable generator and leave it in the back of your pickup..get a long shore power cord and go with that..you can even combine two smaller generators,that way if you don’t need the ac units running you could use just the one. Chain it to your fifth wheel hitch and get a cover for it

Originally Posted by immortl

I believe it did. I'm not at the trailer currently, but have someone checking for me. I'm not sure what that all entails though. Looking at pics of the front storage, there is nothing obvious jumping out at me though.



Thanks,
Joe

Try here.... https://www.norwall.com/brands/Onan-...SAAEgIQD_D_BwE

[immortl]

So yes, it does have a generator prep package. I'm not really going to have a good sense of how well it'll fit, what bracing would need to be added, and if I could build some sort of sliding tray for it until I'm at the trailer and can get my eyes and hands on the space in person.


We currently are in WA, bought the trailer from a guy in FL, and had it shipped up to family in NJ early last Spring. Should have had it shipped out here I guess. Didn't think it would take us this long to get to it. I'll have to be patient for another few weeks.



Thanks for the link above with all the Onan RV generators. Looks like there is a 6k model now too. I'll have to compare the measurements, that could be a decent alternative.


Thanks,
Joe

[notanlines]

With a true genprep which I'm sure this will have, you will need no further bracing. It is very close to plug and play. The generator is air cooled through the bottom of the RV. There is plenty of info to be had online for the installation, and I'm certain any GOOD tech can handle it if you choose not to. You can choose propane, works great, never a carb problem. We have the 6500 propane in the Suites and wouldn't be without it. Noise is no problem. People who have never had a generator under the bedroom won't understand, but it is no problem, believe me. Keep in mind that you have two 30 lb tanks, we have two 40 lb tanks.
You might be better served with the 6K gas and fuel it from 2 or three 6 to 12 gallon boat tanks. Actually mounting a certifiably safe gas tank on an RV might be a trick. Not impossible, but a trick none the less.
If you would like actual measurements of the 6500 propane just PM me.

[wiredgeorge]

Originally Posted by notanlines

With a true genprep which I'm sure this will have, you will need no further bracing. It is very close to plug and play. The generator is air cooled through the bottom of the RV. There is plenty of info to be had online for the installation, and I'm certain any GOOD tech can handle it if you choose not to. You can choose propane, works great, never a carb problem. We have the 6500 propane in the Suites and wouldn't be without it. Noise is no problem. People who have never had a generator under the bedroom won't understand, but it is no problem, believe me. Keep in mind that you have two 30 lb tanks, we have two 40 lb tanks.
You might be better served with the 6K gas and fuel it from 2 or three 6 to 12 gallon boat tanks. Actually mounting a certifiably safe gas tank on an RV might be a trick. Not impossible, but a trick none the less.
If you would like actual measurements of the 6500 propane just PM me.

I think the diesel genny he is looking at is water cooled, if that makes any difference. Not sure how water cooling would work on a generator. Probably water jackets adjacent to cylinders and a water reservoir or similar?

[immortl]

So fairly early on in my research I wrote off propane fueled generators as it seems they burn through propane very quickly. How long do you get from your 40lb tanks? Perhaps I should take another look at them?



I agree, mounting a gas tank may prove challenging. That's another reason why I was thinking diesel. Diesel isn't quite as volatile. In a pinch, I could even snag some from the tow vehicle (FASS fuel system, easy to get to). Or I was theorizing with my diesel mechanic, I could even add another tank to the bed, link the 2 together, and rig up valves and a line to supply generator from the tanks in the truck. Cool idea, but probably not worth the effort. In talking with generator place and diesel mechanic, I believe I can just use a square fuel cell from Summit Racing as a diesel tank to feed the generator. Curious if anyone has done anything similar?


It seems the Onan 6-10k watt diesel generators are all the same size/weight/engine, it's mainly the output that varies. I do know the Onan 5500 gas one will fit. I'll check out the size on the larger 6500 version next.


So even for the 5500/6500 gas generators, do you guys have them bolted in place or on sliding trays in fifth wheels? Do you have to remove them for maintenance and troubleshooting?



Thanks,
Joe

[notanlines]

I believe you will generally find that motorhomes have them on a slide and fifth wheels do not. The oil and air filters are a dream to change. The spark plug on the back side is a uh, well, uh let's say it is a bear! I know of no one who has ever removed their generator for any reason.
Propane use is high, too high to use for a permanent no power setup. About 8-16 hours per tank with both AC's operating.

[dutchmensport]

Water weighs in at 8 pounds a gallon. I imagine diesel fuel weighs about the same.

At 16 gallons you are also adding another 128 pounds. At 20 gallons you are adding 160 pounds of weight in addition to the existing 420 pounds for the generator. And although it might not be much, how much does the actual fuel tank weigh empty?

It's something else you need to consider.

[Javi]

Originally Posted by dutchmensport

Water weighs in at 8 pounds a gallon. I imagine diesel fuel weighs about the same.

At 16 gallons you are also adding another 128 pounds. At 20 gallons you are adding 160 pounds of weight in addition to the existing 420 pounds for the generator. And although it might not be much, how much does the actual fuel tank weigh empty?

It's something else you need to consider.

7.2 pounds per gallon

[Javi]

Originally Posted by immortl

So fairly early on in my research I wrote off propane fueled generators as it seems they burn through propane very quickly. How long do you get from your 40lb tanks? Perhaps I should take another look at them?



I agree, mounting a gas tank may prove challenging. That's another reason why I was thinking diesel. Diesel isn't quite as volatile. In a pinch, I could even snag some from the tow vehicle (FASS fuel system, easy to get to). Or I was theorizing with my diesel mechanic, I could even add another tank to the bed, link the 2 together, and rig up valves and a line to supply generator from the tanks in the truck. Cool idea, but probably not worth the effort. In talking with generator place and diesel mechanic, I believe I can just use a square fuel cell from Summit Racing as a diesel tank to feed the generator. Curious if anyone has done anything similar?


It seems the Onan 6-10k watt diesel generators are all the same size/weight/engine, it's mainly the output that varies. I do know the Onan 5500 gas one will fit. I'll check out the size on the larger 6500 version next.


So even for the 5500/6500 gas generators, do you guys have them bolted in place or on sliding trays in fifth wheels? Do you have to remove them for maintenance and troubleshooting?



Thanks,
Joe

Answers... https://www.cummins.com/generators/rv-generators

[immortl]

Good point on the weight of the fuel tank. For the diesel Onans, they have a fuel pump and the place I spoke with that sells/installs them said it ought not matter too much where/how the fuel cell is mounted. Not sure what space is available under the trailer, but when I'm at it in a few weeks, I'll explore mounting locations, keeping in mind the need to add a filler neck.


When it comes to gas generators, what's the preference these days, carburetor or EFI?



Thanks,
Joe

[JRTJH]

Originally Posted by immortl

...

When it comes to gas generators, what's the preference these days, carburetor or EFI?

Thanks,
Joe

For me, it's not as simple as "choose one".

Carburetor gensets are usually significantly cheaper, easier to "owner maintain", but, they also require jet changes with large altitude changes, are not as easy to store for prolonged time frames.

EFI gensets cost more, if there's a problem with the fuel system, usually need to be repaired by someone other than a "shade tree mechanic". The "good parts" are that they usually will compensate for altitude changes and are not as prone to "jet clogging" like a carburetor genset. And, I don't know of any "dual fuel" EFI generator, so no propane use with the EFI gensets (from what I understand).

Both had distinct advantages and disadvantages that make one or the other a better choice, depending on the buyer/user.

[Hblick48]

I have an Onan 4000 gas generator that came with my rig when purchased. I found this marine gas can:

https://www.amazon.com/Corporation-8...8191574&sr=8-2

I was able to mount the gas can underneath the generator using bungee cords. Easy to remove for refill.

When I know I'm going to use the generator a lot, I also carry a 5 gallon gas can in the bed of the pickup. I like gas because you can always find a gas station.

[immortl]

Thanks for all of the help and thoughts guys, I appreciate it. My current thoughts are running along the following lines.


Overall Generator - be able to run 2 AC units, regular 'stuff' in the RV, extra load presented by my networking and server gear. Once I figure out my ballpark overall load, I'd like to size the generator larger than that, to keep avg load well under maximum output for efficiency. Looking for a press the button and it works solution as wife may be solo sometimes. Prefer not to have her have to lug around generators, connect in parallel, run cables, etc...



Propane generator - won't get the run time we would like as they consume propane at a rapid pace, for now not on the short list.


Gas generator - could work. Potential challenges legally adding fuel tank to the RV, could use external boat fuel tanks. Gas is more volatile than diesel, but then we'd also have gas along for her Harley. Gas generators are lighter/smaller - overall weight and pin weight bonus, no issues with fitting one in the front storage bay. Gas generators few thousand dollars cheaper than the diesel versions. Reinforcing front storage bay probably not necessary.



Diesel generator - same fuel as truck, longevity and efficiency, less volatile than gas, lower rpms. Heavier at 420lbs, larger but according to measurements taken by brother, probably would still fit in the bay opening with mostly plenty of room once inside the bay, little tight front to back. May/probably have to beef up mounting supports in the bay. Less concern about fuel vapor volatility. Compared to a gas generator, eating up 200 or so extra pounds of payload capacity.


At this point, I think the next step is to get to the trailer and check things out in person. Main deal is to see if there is somewhere else underneath the trailer to mount a fuel cell or if a fuel cell fits in the front storage with the generator. I don't think I'd want gas in there with the generator, but diesel I'm ok with. If there is room for a fuel cell underneath somewhere and I can get a fill neck to it, then I'm not sure. 7kw gas would probably provide enough power and saves me a few thousand on generator cost and may not need to beef up the mounting supports...


As I write down my thoughts here, a gas generator is looking more appealing than I initially thought. We got a really good deal on our 5th wheel this past winter (about half the average selling price). If I went diesel and spent 13-15k on it and associated parts/work, I'd almost be spending just under half again as we spent on the overall trailer.



Thanks,
Joe