Why no inverter generators onboard?

**Ranchertx** · 08-08-2020, 07:45 PM

Did you replace the fuel pump on the genny yet?

**Steve & Kathy Rasmussen** · 08-08-2020, 08:22 PM

Remember, inverter generators allow the engine (prime mover) to slow it's speed (rpm) down with lighter loads, RV installed gen sets require a certain amount of air flow for cooling the engine and generator. That fan is direct coupled to the engine, and if you wanted an inverter generator (alternator) to be bolted to the QG or QD ONAN, under reduced loads, you would not get proper cooling for both engine and alternator. I suspect that is at least one issue that may have made "inverter generator" manufacturers to decided to stay out of the market. BTY - ONAN (Cummins) does make at least one QG EFI genset - gets rid of the carb issues.

**Roll With The Changes** · 08-09-2020, 04:43 AM

To the original question... Why don't they offer inverter generators? Why don't they put soft starts on all air conditioners? And a thousand other things that make you wonder why.

I went through the same research a few years ago and asked all the same questions. When I set mine up, I wanted the option to back feed my house during power outage so 240 volts was a must. I set my system up for different reasons but somewhat by accident I ended up with a really nice system for the RV.

The summary: My 7kw 240volt Honda inverter generator cost a little over $4k a few years ago. In RV speak, I basically have 30 amp 240 volt service onboard. I can run both AC's, microwave and coffee maker all at the same time for half the price of the available on board generators. With EFI, fuel consumption and noise are on par with the off the shelf Onans.

So again the question. If I can DIY this kind of system, why can't the expert engineers do it?

**Ranchertx** · 08-09-2020, 05:11 AM

Originally Posted by Roll With The Changes

To the original question... Why don't they offer inverter generators? Why don't they put soft starts on all air conditioners? And a thousand other things that make you wonder why.

I went through the same research a few years ago and asked all the same questions. When I set mine up, I wanted the option to back feed my house during power outage so 240 volts was a must. I set my system up for different reasons but somewhat by accident I ended up with a really nice system for the RV.

The summary: My 7kw 240volt Honda inverter generator cost a little over $4k a few years ago. In RV speak, I basically have 30 amp 240 volt service onboard. I can run both AC's, microwave and coffee maker all at the same time for half the price of the available on board generators. With EFI, fuel consumption and noise are on par with the off the shelf Onans.

So again the question. If I can DIY this kind of system, why can't the expert engineers do it?

That Honda is over $7,000 now. With onboard you also get a fuel tank capacity 4 times bigger.
Do you keep the Honda in the truck, or is it built in? If it is built in, did you put it on a sliding tray?

**Roll With The Changes** · 08-09-2020, 05:38 AM

Just looked it up and $4500 is the going price on the street (EU7000is).

I have it permanently mounted on the back of my 300GK. Makes the rig 2 feet longer, but thats actually not very noticeable because its not the full width. I built an aluminum enclosure for it so it looks nice. I installed a remote start and transfer switch so in operation its just like an installed on board setup. I am thinking about some kind of fuel tankard transfer pump on the truck, but so far that has been a huge problem.

**Overtaxed** · 08-09-2020, 05:58 AM

Originally Posted by Ranchertx

Did you replace the fuel pump on the genny yet?

Not yet. The fuel pump that's on it is was tested by Onan as "good" while the problem was happening; my latest attempt is to regulate down the fuel pressure coming from the secondary pump into the primary (generator mounted) pump because the latest thought is "it's now getting too much fuel" because the secondary pump was putting out 3PSI. If that's unsuccessful, I suppose I might look at the fuel pump on the genset next, but I'm not convinced that's it (other than the source of the original problem because that pump has almost no lift and it's being asked to pull fuel for 30FT, possibly uphill, to the genny, it's clearly beyond spec even on a moderate hill for pulling fuel from the rear mounted tank to the genny on any toy hauler).

**Overtaxed** · 08-09-2020, 06:09 AM

Originally Posted by Steve & Kathy Rasmussen

Remember, inverter generators allow the engine (prime mover) to slow it's speed (rpm) down with lighter loads, RV installed gen sets require a certain amount of air flow for cooling the engine and generator. That fan is direct coupled to the engine, and if you wanted an inverter generator (alternator) to be bolted to the QG or QD ONAN, under reduced loads, you would not get proper cooling for both engine and alternator. I suspect that is at least one issue that may have made "inverter generator" manufacturers to decided to stay out of the market. BTY - ONAN (Cummins) does make at least one QG EFI genset - gets rid of the carb issues.

They also actually DO make an inverter generator, at least one in the QD line that I've found:
https://www.absolutegenerators.com/c...-liquid-cooled
https://www.cummins.com/generators/onan-qd-8000

And you're right, they do also offer EFI (which man, I wish I had with all the fuel delivery issues I had with mine!). But that 6KW, diesel generator has a selling price of 8,400 dollars, so it would be an uplift from the generators that GD puts in, but not out of sight. I can only imagine how much less fuel a diesel inverter uses compared to a gas "open frame"/constant RPM style generator! Just seems like coupling that inverter head to a QG existing gas engine for "middle" price point would be a popular product. Or, honestly, just getting rid of all the gas generators and going to diesel; a much better fuel for something like a generator that's going to run long periods of time at rather constant load.