I’ve been wondering about generator fuel consumption, and the difference between inverter and conventional generators. Either my choice of search terms is terrible, or Google isn’t what it used to be, or there isn’t much data out there. Many of the manufacturers list fuel use at 25% output power, which is not that interesting for battery charging.
I came across this webpage, which is old, but at least has some data. Scroll all the way down for a spreadsheet with all the tested generators included. It may partly explain why the inverter generators are spec’d at one quarter power.
KentP. I think you are referring to ChrisOlsen’s post #26 where finally a Honda 3000 inverter-generator got added to the mix, yes?
Read also bob g’s reply on the follow up post #27 about specialized refined DIY water cooled diesel engine generator systems.
The comparisons here on this fieldlines topic are too narrow of pursuits only about using the least bought out taxed spec grade of fuels not factoring in at all other, very real concerns.
Size and weight. Those water cooled diesel are heavy, heavy. Movable on big wheels if the shaking doesn’t destroy the framework.
Availability and cost of repair parts. Even lubricant costs.
Noise. Inverters-generators even opened frame are quieter as mostly running at lower rpms. Lowered rpm’s means they are pumping less cooling air versus 3600 rpm air-cooled. Generating less internal wear too.
If you want the least used fuel by the quantities or weights measurements then of course diesel fueled. Here Washington State pump diesel carries an added full 30% higher price due to punishing carbons taxes. So a gasoline inverter-generator can beat the diesel in actual costs to buy, maintain, and especially to buy out, fuel.
If you want the cleanest burning with the very least maintenance’s and easiest overall operating then that would be a propane fueled inverter-generator.
Here Washington State you can buy propane by the gallon for at least 30% less than pump gasoline. Less Btu’s per gallon, yes. Less power in the same sized generator, yes.
But what will be the overall costs for a full years operation, for the kW/hrs you will need?
I am betting with my pocket book a larger propane fueled inverter-generator will be best overall. This will already have the 240 VAC.
And if ever the real needs-must drives in your little corner of the world these are the ones easiest to convert to charcoal gas or woodgas.
Do not let idealizers hooked on one factor distract you from the overall realities you will have to live with.
I fell down that engine rabbit hole for a few years. Still got the hopper; water cooled, Chinese ‘ChangFa’ diesel engine to remind myself.
Regards
Steve unruh
Yeah, there is that to consider. I maybe I should keep my wallet in my pocket, be content, get the Lister-Petter and old Onan running and wired, and put some solar panels in the sun where they can do some good. Easier to window shop when it’s raining
The inverter generators work best when you aren’t maxing it out, because they can slow down the engine to reduce fuel usage. At full power, there isn’t a fuel consumption savings. Most of the newer ones probably have smoother waveforms for output and less variation in the frequency but for battery charging, it probably doesn’t matter that much. However a newer engine may consume less fuel.
Your best bet dollarwise is probably solar panels. Then you can keep your old generators for back-up when there is an issue with the sun or a larger then normal load. Costwise per kilowatt any generator isn’t going to beat solar. Once you calculate in the cost of wear and tear on the generator im not even sure chargas beats it.
I just ordered the stator and rotar assemblies. Planning on a DIY scratch build, I have not decided if Im going to go with a single cylinder or V Twin. Id like to go for a V Twin for the added power when wood fueling. Plus oil system for longevity.
Anyways Ill more than like create a new thread when I get there. We just got an order that should free up some finances for this project.
Yes all exactly true SeanO.
The advantages of the IC engine inverter-generators IS because they can be ran at varying speeds and still have a measured stable frequency wave form and output voltage. They actually self monitor that voltage and will disconnect loads protecting them and itself before voltage sags and brownouts.
Sure. Than a higher capable systems can be made to emulate a small system. You will save fuel and wear then. Less fuel used to have to have to be bought out; or produced, does not mean more efficient use of that fuel however in an IN versus OUT comparisons.
On many of the smallest IC engine-generators use this variable speed capability to drive up poor little 79cc engines in the inverter-generator output ranges of 1000 to 2200 watts up into 5000+ RPM continuously. That actually does smooth out 4-stroke single cylinder power shaking felt. But inevitably increases engine wear especially with the 100+ hours and more oil changers users.
Using tiny 79cc engine is strictly a U.S. EPA regulations Emissions thing. 80cc and above engines must have fuel tank vapor recovery systems. Honda was brilliant developing thier oversized vapor recovery fuel caps systems. Then able to comply. And use larger engines.
KentP. then there is me. I can no longer tolerate an engine screaming along at 3600 rpm hour after hour after hour. Too much of that lifetime now. I flipped. Now I want to run away to find an axe to run back, wanting to kill it.
And I am exprenced smart enough to know well about gasoline carburetor throttling air strangled losses. Fixed driven cooling fans absorbing more power when over-sped up.
No matter. IF you have an existing 3600 rpm engine generator then go ahead and wear it out.
But buying a new unit. ??? Think. Think. Hard. About all factors of choosing. The most important the full from bought new to ending usability due to the engine just too flat worn out low on compression. Low on power capabilities then. Hard to start, then. Blowing oil smoke; consuming lots of oil running.
Your fieldlines thread-post you linked into was great because the charting guy began using a worn but repaired still useable 4000 hour engine generator. Most roll thier eyes thinking I am way out there, overly optimistic; high on good PNW wacky-toe-baccy when I make such hours useable claims on 4-stroke air cooled single cylinder engines. Nope. Nope. My goal on all of my small engines.
Regards
Steve unruh
I can tolerate them, but I don’t much like it. Our Lister-Petter and Onan generators are 1800 rpm, and amazingly, so is the antique Kohler 90-driven 500-watt with the steel-cable recoil starter (the one with the floating valve ). That last one is competitive with the Lister for highest weight per watt.
Separate topic: I was looking for replacement parts for a Champion 9000-watt inverter-generator, and found from the parts diagram that they mount the rotor and stator under the blower housing, behind the recoil starter. There will be no engine swapping on these units without a lot of pain. Too bad, the Champion genny looked good otherwise.
edit: I think the ignition for the Champion generator is controlled by the inverter module. It has a separate energizing coil that seems to be in with the alternator rotor. It doesn’t have a conventional flywheel with magnets, as far as I can tell.
If the plug wire is comeing from the front engine cover it has the typical coil / flywheel ignition system. I know our 8750 inverter unit has this standard system. The engines on all these other brands are the same engine, so they should also have this same system as well.
KentP. I just detail looked over the Champion 9000 open frame inverter-generator wiring diagram.
it does show an “Ignition winding” in the main stationary wound output coils assembly.
It also shows a solid state “Igniter Module” affixed under the outlets control face panel.
Then it shows a whole separate “Magnator trigger” winding.
From the interconnections I’d say the Ignition winding is suppling power thru the Igniter module for the ignition coil.
The Magnator trigger a base crankshaft position signal to the Igniter module.
The Igniter module rectifying the AC from the Ignition winding to DC to power the ignition coil; and calculating actual ignition timing wanted and switch triggering the ignition coil.
The CO detector module and oil level sensors are in there too and able to disable/interrupt the ignition coil primary.
So far as the recoil cover maybe instead view this crank shaft as reversed from what you’ve seen. The big power delivery tapered shaft output side having the cooling fan; fan air housing and recoil starter covering this all.
The opposite crankshaft stub doing then little except that Magnator triggering.
Very much different from the Harbor Freight 9000 and others systems using two cooling fans on both ends of the crankshaft. They have a a very special output side cover casting to mount the opposing casting the output coils are reverse mounted into.
This Champion and others; as you say; would have to have a very special base crankcase/cylinder casting to mount the output power coils assembly.
I stand corrected. The Predator open-frame inverter generators do have magneto ignitions. There appears to be a magnet, or a pair of them, on the outside of the alternator rotor. Unlike at least the larger enclosed inverter generators, there is no separate flywheel. The alternator must act as the flywheel, like the blade on some rotary push mowers. There’s no second oil seal or output shaft. Everything is mounted on the blower housing side, under it. I don’t think there’s a way to fit these to a replacement engine without a lot of trouble, unless you can find one with the longer shaft on the blower side.
Steve, I think that’s right. There are variations, but it looks like if you want to be able to swap in a replacement engine, the Predator 9500 MIGHT work, most of the others are going to be tough. I’m thinking the only way may be to start with an engine, and go from there, like Matt is doing.
Apparently somebody makes stackable generators, but the “Series-Parallel Box” has an additional cable, judging by the picture. With a separate synchronizing cable, setting them up out of phase is apparently possible.
This is great news for your project needs KentP.
Reading the info it is for sure two separate 120 VAC inverter-generators.
Watch the video for sure. A lot of info in that too.
The green wire bonding together of both inverter-generators.
Lastly starting up a fairly big for sure split phase 240VAC electric motor driven air compressor. Your deep well pump needs shown fulfilled right there.
Now you need to try and search up the manual with the internal wiring diagram on these particular GenMax units to see just where the two wire phase taps are internally wired into.
Maybe could be ported in on other inverter-generators.
Maybe into special added circuitry in these particular GenMax’s unitized inverters.
$99. USD is certainly affordable.
Good find man.
Best Regards
Steve Unruh
The rated rpm is 4850 , so maybe 4 kw starting is possible. Running kilowatts is 3.2 on gas, 3 on propane. The sync cable is only used for series-stacking, not needed for parallel use. The cable is connected to a dedicated port on the inverter module
I did read through the manual KentP.
You would need to use these specific purposed designed for phasing inits.
Now the units you found themselves.
Pretty darn amazing specifications and design-use capabilties.
I detail read the GENMAX site. Then the Amazon offing up including the two so far reviews.
Here are three perspectives costs-risks wise:
A previous Honda EU2000 will set you back ~999.-1200. USD. Fine, fine unit with a well known history and capabilities. ONLY 120VAC. Not already set up for propane. Having to buy-more add in a boat tank capacity for extended running. We have one already.
Then I did buy an open frame Yamaha 2800 new for $1,600. USD. As 1/2 the price of the Honda’s 3000’s. Still only 120VAC. At 72 pound to be my heaviest solo possible pack able. 172CC? engine as I recall. Never gets above ~4000 RPM.
This particular open frame GENMAX says id 58 pounds. Plus a separate gasoline tank; or propane tank
Would have been cost and capability wise a much better deal. For the price if my Made-in- Japan I could have bought two of the GEXMAX’s; The converter box and fuel tanks for dual fuel.
Then my bought Harbor Freight 9500 inverter-gnerator units. Then do have 240VAC with enough wattage for air compressors and deep well pumps.
459CC engine in it on Eco lowered RPM will still use more fuel that one of the GENMAX’s
And at $2200. I for my made-in-China quality did still pay more. The only advantage is having at least 1700 watts more top end capability.
As I see it the two GENMAX’s will give you at least four different levels of needs fuel-in consumptions. With as bought dual fuel capability.
Younger man mini-car roads speed racer most of my cars were geared as 4000 RPM for 60 MPH. Yep. Greater wear and a bit more noise.
But far less more wears than you’d think if using the very best modern fully synthetic engine oils. With one of the true proven engine oil supplements.
What I do, and have done for years now in all of my small hard worked 4-stroke engines.
Damn, man. And I just ordered in a different small electrical generator for extended wears oils testing and be my loaner-out unit.
Knowing this just a week ago I happily been your buy-it, use-it tester.
Steve Unruh
Here watch this one that popped up to my attention. You will have to slow the playing speed down to .25 and still have to click on, and off pause, a lot to see the details. I watched especially to see the manufacturing design for heats managements and the actual assembly quality. Impressive.
I do believe the man did use this little 79cc engine as continuously as possible for his claimed 2 1/2 years. With hundred and hundreds of stops to refuel. And later to do a lot of oil level topping up. So not an actual 20,000 hours running. But still outstanding.
Interestingly; he makes no claims for any of the exclusive-use super brands of oils like AMSOIL; Redline; Royal Purple. No claims for a super oil supplement either.
Then a video popped up with a guy choosing to run three of these Predator 2000’s in parallel. Sounds like the old multi-engine bombers planes or 50’s air liners.
S.U.
I know a guy from a homesteading site I’ve been on for a long time. Been off-grid for 14 years and only got PV in the last three or four. Before that his sole source of power was a couple of 2000 W Honda inverter generators. Admittedly he had a small engine repair shop for a while, so he had skills, but he claimed 23000 and 24000 hours out of his generators. I was a little skeptical but he insisted he was not blowing smoke up our exit ports. Only problems I remember him mentioning was some kind of nylon gear set, maybe he recoil starter, wearing out. Kind of make me understand why someone would spend all the extra money for the Honda.
). That last one is competitive with the Lister for highest weight per watt.
