Onan CMQD 7500 questions

[RiverDave]

So I found a generator that I believe will solve all the problems I am having with my sign truck..

My biggest question is will this generator idle on a low load and not wet stack like my current one? It was advertised as an Rv generator so I would think it would but then I saw “commercial power” on it so I’m not sure?

Someone on here has to know..

 

[monkeyswrench]

That is the typical, "small" diesel pusher Genset. I think the differences between the QD and CMQD had something to do with the fuel system and the charging systems. The CMQD has a charging circuit I believe for it's own battery if it were to be standalone. I wouldn't think they'd have an issue at low load, but really the lowest load I've seen one on was to charge the house batteries.
**check the coolant reservoir. I've replaced a couple in the past few years. they seem to split on the part line. They can also crack at the tube fittings, then the tank would be empty.

 

[Taboma]

Dave, here's a Onan RV handbook that seems to cover that model that might provide you with some info in that regards.

https://primetimerv.com/files/component-manuals//Cummins%20Onan%20RV%20Generator%20Handbook.pdf

 

[RiverDave]

So this would work for me without making the whole parking lot smell like diesel..

Or pumping a bunch of fuel into the air..

RD

 

[BHC Vic]

So this would work for me without making the whole parking lot smell like diesel..

Or pumping a bunch of fuel into the air..

RD

I’m going to guess it’s still going to stink up the parking lot

 

[mjc]

How much power do you really need?

 

[MooreMoney]

I am surprised a little honda generator wouldn't power your sign.

 

[HTTP404]

Run an array of batteries and just recharge with the generator as needed.

 

[poncho]

I am surprised a little honda generator wouldn't power your sign.

I'm making an assumption here but if the truck is diesel, then he wants a gen that will run from the main tank.

 

[mjc]

Run an array of batteries and just recharge with the generator as needed.

This would be my plan.

 

[kat_williams]

I think a generator in an RV would always have some sort of load on it. It's powering all the systems and such and charging the batteries. And if everything is off then there would be no reason to run the generator. Do you know what your running load is? Then you could find a generator to match your needs.

 

[Your ad here]

Why are you wanting to go with a diesel generator?

 

[paradise]

Run an array of batteries and just recharge with the generator as needed.

That would be super easy. Tons of auto generator starters for motorhomes that would tie right into this onan.

 

[Go-Fly]

So I found a generator that I believe will solve all the problems I am having with my sign truck..

My biggest question is will this generator idle on a low load and not wet stack like my current one? It was advertised as an Rv generator so I would think it would but then I saw “commercial power” on it so I’m not sure?

Someone on here has to know..

S

I was wondering how your cash cow was working. I've run my fair share of generators on job sites. My rule of thumb is, run them at half load minimum. Never let a generator run without a load for very long. The focus of the engine, in a generator is to maintain 3600 or 1800 RPM. Different carb set up then a car at a stop sign. Without the proper load all generators stink. I have meters on both legs of my home backup generac. It says right in the owners manual to keep a heavy load on it. We turn on lights just to up the amps that we are using. Funny to have all those lights on when the power goes off. Even more strange to go to bed and leave everything on.

 

[Singleton]

Why are you wanting to go with a diesel generator?

Truck runs on diesel. 1 tank for both

 

[Desert Whaler]

Would be nice if a bank of Lithiums could run it for a few hours, then a Honda 3200 (60 lbs) to charge them with pass-through charging.

Is there such thing as a 'PTO' for electricity on a diesel ? . . . Like beyond what the alternator normally puts out ?

 

[Your ad here]

Would be nice if a bank of Lithiums could run it for a few hours, then a Honda 3200 (60 lbs) to charge them with pass-through charging.

Is there such things as a 'PTO' for electricity on a diesel ? . . . Like beyond what the alternator normally outs out ?

It may have a 4R100 with a PTO but running the 7.3 to power that will be loud.

 

[DoughBallin14]

Hmm 48v conversion? EG4 3000 or 6000 all in one inverter, charger, mppt controller, a fee residential panels to help charge during the day and a buck converter back down to 12v if needed, autostart little honda to help charge or run the charger at night with some server rack lifepo4 48v 150ah batteries. Have to add up he needs to run.
4 rack batteries close to 28kwh of power.

 

[rrrr]

The properly sized generator will cost wayyyy less than all that battery stuff, and work without issues in 110° summer conditions. A bunch of LiPo batteries won't.

Bolt the generator on the truck, connect to the existing power distribution system, and go get a beer. It's been in the shop long enough.

 

[Uncle Dave]

So I found a generator that I believe will solve all the problems I am having with my sign truck..

My biggest question is will this generator idle on a low load and not wet stack like my current one? It was advertised as an Rv generator so I would think it would but then I saw “commercial power” on it so I’m not sure?

Someone on here has to know..

View attachment 1467043

Yes it will idle down and not wet stack. It's an inverter and varies RPM based on load.

(pretty sure) This is powered by a kubota d722 which is a little gem.

I built dog grooming vans based on the newer 8K version, both the 7500's and the 8000's are just awesome
I was closing in on 8K hours on one with just basic maintenance and zero hassles.

 

[Bigbore500r]

@RiverDave I think i've asked before - what is the peak and running load of the sign truck?

Once you have that info - picking the right generator is much easier........

I know you WANT diesel, but generators like this don't give a shit how small the load is at times, and just run forever without making a smell, or noise, or much of anything other than smiles and high-fives . . .
They are also incredibly fuel efficient, for gas.

Theres a reason you see these powering every catering truck, every street vendor, every dry camped RV all night long, etc . . . .and those RV's have a 7500 or 10000 diesel genset but elect not to run them, and instead roll a Honda 3000 or Predator 3500.

 

[240Hallett]

@RiverDave I think i've asked before - what is the peak and running load of the sign truck?

Once you have that info - picking the right generator is much easier........

I know you WANT diesel, but generators like this don't give a shit how small the load is at times, and just run forever without making a smell, or noise, or much of anything other than smiles and high-fives . . .
They are also incredibly fuel efficient, for gas.

Theres a reason you see these powering every catering truck, every street vendor, every dry camped RV all night long, etc . . . .and those RV's have a 7500 or 10000 diesel genset but elect not to run them, and instead roll a Honda 3000 or Predator 3500.


View attachment 1467371

Could something like this be fed fuel with an auxiliary system? Tanks are kind of small. The 3500 I have advertises 11 hours at 25% load.

 

[Taboma]

Would be nice if a bank of Lithiums could run it for a few hours, then a Honda 3200 (60 lbs) to charge them with pass-through charging.

Is there such thing as a 'PTO' for electricity on a diesel ? . . . Like beyond what the alternator normally puts out ?

I don't understand why a PTO for electricity when it's already generating electricity ? To charge batteries ? Then connect a battery 120V multi-bank battery charger.
Load is load, generation by any means requires energy to be expended, be it from the main generator or any additional accessories.
When the thread on this exact same subject ran amuck previously numerous suggestions were submitted by the members. The thread died as it seemed RD had found a solution or was too involved elsewhere to continue his participation, now we're circling back to whence we started.

 

[Singleton]

Could something like this be fed fuel with an auxiliary system? Tanks are kind of small. The 3500 I have advertises 11 hours at 25% load.

Yes. I have seen aux tank setups before.

 

[RiverDave]

How much power do you really need?

It would be nice to power the vending trailer at events.. so I’m guessing 6kw’ish total for both..

 

[Bigbore500r]

Could something like this be fed fuel with an auxiliary system? Tanks are kind of small. The 3500 I have advertises 11 hours at 25% load.

The honda has a 3.5 gallon tank, which is alot bigger than other generators it's size.
There are extended run tanks out there that just feed the main tank, it's easy to do.

Honda EU3000is

A one-of-a-kind fuel extender; adding run time to all of your gas powered machinery. Run your Honda generator in excess of 72 hours without refueling.

moregasnow.net

 

[Ziggy]

Dave could install a set of kustom semi stacks and put that smoke over everyones head.

.
I honestly wish I had a qualified & helpful response.

 

[RiverDave]

I am surprised a little honda generator wouldn't power your sign.

A 3500 probably would.. but I want something that can run 14 hrs a day in the heat of the summer and tie into the 90 gallons of fuel we put under the bed of the truck.

RD

 

[RiverDave]

I don't understand why a PTO for electricity when it's already generating electricity ? To charge batteries ? Then connect a battery 120V multi-bank battery charger.
Load is load, generation by any means requires energy to be expended, be it from the main generator or any additional accessories.
When the thread on this exact same subject ran amuck previously numerous suggestions were submitted by the members. The thread died as it seemed RD had found a solution or was too involved elsewhere to continue his participation, now we're circling back to whence we started.

I had thought I found a solution but it didn’t work out.. so I’m changing directions to an Rv generator.

 

[RiverDave]

@RiverDave I think i've asked before - what is the peak and running load of the sign truck?

Once you have that info - picking the right generator is much easier........

I know you WANT diesel, but generators like this don't give a shit how small the load is at times, and just run forever without making a smell, or noise, or much of anything other than smiles and high-fives . . .
They are also incredibly fuel efficient, for gas.

Theres a reason you see these powering every catering truck, every street vendor, every dry camped RV all night long, etc . . . .and those RV's have a 7500 or 10000 diesel genset but elect not to run them, and instead roll a Honda 3000 or Predator 3500.


View attachment 1467371

I’d guess the peak load at an event with the vending trailer is 6-7kw

 

[Bigbore500r]

It would be nice to power the vending trailer at events.. so I’m guessing 6kw’ish total for both..

I’d guess the peak load at an event with the vending trailer is 6-7kw

That 7500 will work, you're gonna smell a little diesel but it won't be obnoxious like the one you have now.

 

[Taboma]

I had thought I found a solution but it didn’t work out.. so I’m changing directions to an Rv generator.

If you're still considering that CMQD Onan and you can get the nameplate model #, Cummins has far more extensive owner's manuals on their website:

https://www.cummins.com/cm-generator-manuals

I realize the link I posted yesterday was extremely generic and different provide worthwhile diesel gen guidance.

 

[lbhsbz]

I’d guess the peak load at an event with the vending trailer is 6-7kw

Why guess?

What does the vending trailer have besides lights? What's the actual load? Whats the actual load of the LED sign? Find the real numbers instead of guessing. 6-7kW will run my whole house and probably my neighbors house under normal circumstances

 

[Your ad here]

Dude just put a quite gas generator on the thing and get it to work or run it as is and just see how it works out. You may have wet stacking problems or you may not.
In reality a diesel generator under 25Kva is just a piece of shit. I get it RVs and boats have small ones but they're bulky for the amount of power they put out and expensive to repair or replace.
Only thing I can think of diesel wise is pull a generator unit from a light tower, build an enclosure, and install it. They have 6kw alternators on them. Budget at least $5000 if you have to replace the engine.

 

[RiverDave]

Why guess?

What does the vending trailer have besides lights? What's the actual load? Whats the actual load of the LED sign? Find the real numbers instead of guessing. 6-7kW will run my whole house and probably my neighbors house under normal circumstances

It’s got an array of lights inside that actually raises generator rpm.. not sure on what that draw is.. a large Rv air conditioner that brings a 4500 to its knees when it cycles, then a charging supply that takes care of two large batteries that run 12 volt for large stereo etc.

RD

 

[RiverDave]

Dude just put a quite gas generator on the thing and get it to work or run it as is and just see how it works out. You may have wet stacking problems or you may not.
In reality a diesel generator under 25Kva is just a piece of shit. I get it RVs and boats have small ones but they're bulky for the amount of power they put out and expensive to repair or replace.
Only thing I can think of diesel wise is pull a generator unit from a light tower, build an enclosure, and install it. They have 6kw alternators on them. Budget at least $5000 if you have to replace the engine.

I firmly believe it’s gonna end up having to be water cooled because of the temps out here.. which is one of a few reasons I’m sticking to diesel. The other thing is someone shouldn’t be able to walk up and turn it off or sabotage it, which is why I’d like to stick to a box style genset and run off the belly tanks.

This thing will be left unattended on the side of highways for the majority of its life.

RD

 

[69hondo]

I have this generator in my coach.
It is very quiet but you are going to smell it.
It will surge to a higher rpm when a load is put on it. even my coffee make makes it surge to a higher rpm.

 

[Travmon]

Do not forget guys one of his goals was also to have others able to plug in out in the desert. The onan you are showing is perfect for the job. They do not stink much not that loud that is why they are in all tge upper class rv’s. MOUNT THAT BITCH BROTHA. !

 

[rrrr]

I firmly believe it’s gonna end up having to be water cooled because of the temps out here.. which is one of a few reasons I’m sticking to diesel. The other thing is someone shouldn’t be able to walk up and turn it off or sabotage it, which is why I’d like to stick to a box style genset and run off the belly tanks.

This thing will be left unattended on the side of highways for the majority of its life.

RD

You'll have a much more reliable and maintainable setup running a diesel fluid cooled genset. Besides that, gasoline air cooled portables won't survive the duty cycle you need.

You're on the right track.

 

[RiverDave]

You'll have a much more reliable and maintainable setup running a diesel fluid cooled genset. Besides that, gasoline air cooled portables won't survive the duty cycle you need.

You're on the right track.

I think so too

 

[Bigbore500r]

You'll have a much more reliable and maintainable setup running a diesel fluid cooled genset. Besides that, gasoline air cooled portables won't survive the duty cycle you need.

You're on the right track.

Tell me you don't dry camp without telling me you don't dry camp

 

[rrrr]

Tell me you don't dry camp without telling me you don't dry camp

I'm talking about 15-24 hours a day for several years in Havasu weather conditions. Mount the diesel. Plumb a fuel line. Connect the output. Run it.

That's a little different than a few weekends at Glamis in the winter.

Why screw around with a generator that's not built for those parameters?

 

[Melloyellovector]

I'm talking about 15-24 hours a day for several years in Havasu weather conditions. Mount the diesel. Plumb a fuel line. Connect the output. Run it.

That's a little different than a few weekends at Glamis in the winter.

Why screw around with a generator that's not built for those parameters?

You’ve got bigger dreams for the truck than Dave
I say throw a Honda in it, it will be sold in year or so anyway, the money saved can go towards the money lost

 

[RiverDave]

You’ve got bigger dreams for the truck than Dave
I say throw a Honda in it, it will be sold in year or so anyway, the money saved can go towards the money lost

This truck will run 6’ish am to 11pm all day 20
Days a month. An air cooled generator isn’t gonna work.

RD

 

[braindead]

This truck will run 6’ish am to 11pm all day

20
Days a month. An air cooled generator isn’t gonna work.

RD

Prove it. I'd throw in some cash to test the theory of how long an air cooled genny would last in the AZ heat vs a diesel. Wouldn't take much, gas genny and a bigger aftermarket fuel tank plumbed into it.

 

[RiverDave]

Prove it

Would you like me to prove that a water cooled diesel commercial generator is a better application for a extreme weather commercial
Purpose? Vs a hobby home unit designed for occasional use?

Or what exactly would you like me to prove?

 

[braindead]

Would you like me to prove that a water cooled diesel commercial generator is a better application for a extreme weather commercial
Purpose? Vs a hobby home unit designed for occasional use?

Or what exactly would you like me to prove?

Sure, why not? A Lotta guys on here think it'll work and you dont...y not make it interesting

 

[BHC Vic]

This truck will run 6’ish am to 11pm all day 20
Days a month. An air cooled generator isn’t gonna work.

RD

You said that like 2 years ago

 

[Your ad here]

Would you like me to prove that a water cooled diesel commercial generator is a better application for a extreme weather commercial
Purpose? Vs a hobby home unit designed for occasional use?

Or what exactly would you like me to prove?

A water cooled diesel generator may be a better application for extreme weather commercial applications. Is your truck a commercial application that sees extreme weather and needs an $18,000 commercial water cooled diesel generator? I get it you paid less for the current generator but that's what they cost new.
If you're worried about air cooled gas generators lasting 1500 hours, then just factor it as a consumable item in this business venture. You buy 2.5 generators a year, it's annoying but is it going to make the business go broke? They may last longer.
As mentioned earlier I see all year long, winter and summer, 3000 watt generators of all types of makes powering small mobile businesses here in Phoenix. Businesses that are making money with that generator. They're going for it and it's working for them. Why have any excuses not to use one when it helps in generating and income.
You're making excuses and just letting your asset sit and cost you money instead of making money. I still say run it with the diesel generator and if wet stacking becomes a problem, deal with it when it happens, if it happens. Don't let some keyboard warriors get in your head and hold up your plans.

 

[DoughBallin14]

If my youngin memory recalls honda did make 2 water cooled gas portable gennys i wanna say an ex5500 and em6500. Those would be good comparisons to your diesel genny. But like you said you have a huge plumbed diesel tank.