Not what I expected.

How many kWh per gallon? Let's find the setting for the most fuel efficiency. I'm using my Honda generator to re-charge my battery bank. This is part of my off grid solar electric system backing up my whole home. The generator feeds 240VAC into a charger to re-charge the lithium battery.
I'm using the 100 Amp charger from Signature solar called the Chargeverter.
The generator is a Honda EU6500, it's an inverter generator. I'm running regular gasoline from the pump, which can contain up to 10% ethanol according to the sticker on the pump.
The battery bank is a LiFePO4 EG4 LifePower4. It is made up of 6 individual server rack batteries into one cabinet for a total of 30kWh capacity.
The inverter is a Schneider XW PRO 6848.
Videos:
1. Previous fuel efficiency test with smaller charger: • Recharging your batter...
2. Chargeverter video review: • Powerful and Affordabl...
3. Schneider Playlist: • Schneider
Affiliate Links:
1. Battery Bank: signaturesolar.com/eg4-lifepo...
2. Chargeverter, 100A, 48V Charger: signaturesolar.com/eg4-charge...
3. Schneider inverter kit: signaturesolar.com/bndl-dc-co...
4. Victron Smart Shunt: signaturesolar.com/victron-en...
Amazon Affiliate Links:
1. Honda EU7000 generator. The updated version of the generator in this video: amzn.to/3ZB8Qqt
2. Genmax Generator. Good choice to save money compared to the Honda. amzn.to/3LdELJ9
3. Victron Smart Shunt, 500A: amzn.to/3FBd1uL
4. Busbar, Pike Industries, 400A, Negative: amzn.to/3mFZDyE
5. Busbar, Pike Industries, 400A, Positive: amzn.to/3ZUVqFJ
“As an Amazon Associate I earn from qualifying purchases.”
Disclaimer:
My videos are in no way intended to be instructional "how-to" lessons. I am simply documenting my project for informational purposes. Property damage, personal injury, or death may result, even when following manufacturer's instructions. I cannot be held liable for such damage or injury. It is YOUR OBLIGATION to ensure that you are complying with any local and federal laws as well as code and permit requirements.
David Poz, LLC

[@brucebugbee6604]

I was a little surprised by the result. I thought the higher current losses in the cables would show up. It would be interesting to see what running it at a lower current would do. Say 20, 30 or 40 amps. I know it would take longer, but it might give some more insight into finding the true sweet spot.

[@mcg6762]

Losses in the cables are in the order of 1 percent maybe. The thing which will determine the overall efficiency the most is the efficiency of the internal combustion engine. It is probably only about 25% efficient but it will depend on the load and that is the factor that matters the most in this test I believe, finding the optimal load level for the engine. Gas contains 33.7 kWh of energy per gallon, so the overall efficiency of this test was about 17.5 percent.

[@jfbeam]

They did show, but they're pretty low, so it's easy to gloss over it. If you pay attention to the numbers, the full system is about 1% less efficient at the 100A load. (80A was ~93%, 100A was ~92%) But with such a low difference, you'd have to "lab accurate" in each test to properly measure it. (each test is using slightly different amounts of gas, he's running the generator without load for various times, and not starting the test with the inverter set to the target current... but for a YT video, it's accurate enough: honda makes a damn good inverter generator, but you are paying for it.)

[@Mike80528]

@@mcg6762 Agreed. The goal here should be to find at what load the generator is the most efficient at. I would think in the 80% load range would be ideal but no idea offhand why I would be thinking that (I may be conflating PC power supply efficiency).

[@tarstarkusz]

@@mcg6762 This is why he should be running a diesel generator. Diesel engines run at higher compression and are above the 25% (maximum) efficiency of a good quality gas engine. When it comes to efficiency, there is really no replacement for compression ratio.

[@veizour]

The idea I love about charging a battery w/ the generator is that the generator isn't wasting fuel on low-current applications (i.e. like a car moving itself at idle). It can charge the battery, potentially while also supplying electricity for needs, so the additional energy potential isn't wasted (except in inverter/voltage efficiencies). I wonder what the math is like on powering a house w/ generator, vs powering a house and charging a battery at the same time, so once the generator is off, the battery continues to power the home.

[@matthewknight5641]

I installed the same minisplit as you and couldnt be happier with the inovair. Its been amazing in my camper. It runs off my solar and batteries 24-7 when we are not in our semi truck. Thanks man

[@benkanobe7500]

I really appreciate all the information you organize and provide links for in your "Show More" sections. I have been using your Amazon links to build up my supplies, tools, and research. Thank you!

[@bigdaadio.K2WW]

Thanks for the test David. I lived off grid, Caretaking for a guy who had 2 of those eu6500's, which got rotated, and ran 24/7. One had 39000 hours on the hour meter, and the motor was NEVER torn apart, burned nearly a pint a day of Castrol full synthetic oil. HONDA is king

[@MrHVAC503]

Love your videos David! You do an extraordinary job of explaining things and cover all the bases. Keep up the good work

[@DavidPozEnergy]

Thanks, I appreciate that.

[@toddshreve]

I just love this kind of thing. I am always doing this kind of testing so I can KNOW what the best settings, values are. Would be neat to do this test again with the newer EFI version of this generator. I'd donate mine for the testing, but I live on the other side of the country!

[@shaunnightfire8269]

Love your videos, Dave. You are charmingly awkward and provide excellent information.

[@Paxmax]

A gallon of gasoline contains approximately 33kWh (if my googly is correct). So, from fuel to battery overall efficiency 17.8% is actually better than I would've guess. Would be cool to try to harvest the engine and exhaust heat too.

[@jjackson3240]

Been a long time now but they did something like that back in the 1970's with I believe a Ford Pinto engine. Used the excess heat for hot water heating. It was likely in a Popular Mechanics issue but I can't be sure anymore.

[@TheMobilefidelity]

That is the way to go for hot water from a generator. It's called Combined Heat and Power, or CHP, or simply cogeneratiron. I worked on a few setups like that for Hotels, hospitals and the like.

[@montey1017]

Yeah he needs a diesel. Gasoline contains a lot of energy but isn't very efficient. Diesel isn't perfect but it's better.

[@reversedon8698]

i would not bother heating whit electricity at this point propane heater would be way better option to heat when there is not enough solar power than wasting on inefficient generator

[@retrofitter]

@@montey1017 I am thinking a diesel DC welder would be the most efficient way to to do this. I've seen people get around 40% efficiency out of their lister cold start low speed generator sets. And connect the DC output directly to the battery battery bank. If the welder uses brushes for DC output care must be taken such that it doesn't backfeed.

[@mrf5347]

As usual, excellent evaluation and testing! God Bless

[@NikolaStamenkovic6]

So the efficiency is the same, 93% efficiency. Good video unpredictable results.

[@jasonvickery9256]

Hey David. I think the 80% rule also takes into consideration that there will be less RPM, less friction , less wear and tear and therefore longer engine life etc. I may be wrong but that was partly my understanding.

[@bumbarabun]

You could be wrong, as with higher load it will run shorter time, so it is not that clear.

[@miltonbailey1656]

I did similar experiment on a smaller generator. I got max power at max generator rating. My belief is that the "rated power" of the generator is the 80% value. The manufacture rates them at peak efficiency.

[@erikslagter3231]

Great content as always David!! 💪🧠🤯

[@billmonday5623]

Here in CT we pay $0.35 per kwhr. I run a Onan marine generator water cooled to charge my bank and heat my shop. The power going in my battery is basically free as I need to heat the shop. I do not have all the gadgets to test my system like you but it's working well for me.

[@dellmerlin6328]

Heating your shop is a great way to get more useful energy from the generator. You get an A+ for doing CHP, Combined Heat and Power.

[@MrKarlPrince]

Great video David, I think you may have been trying to double count the 80%, the 5500 watt rated output is 85% of the max output, and is what the generator is designed to run at extended periods for. There are arguments for lower output causing less strain and wear, though conversely that puts more hours on the parts as well. You may also want to consider if the EG4 charger running at max is getting too toasty. Personally probably would go for 90-95 amps and a strict regime of quality oil changes to maintain engine efficiency.

[@lang9872]

Thanks for your work 👍👍👍

[@benkanobe7500]

I like that you don't let your expectations overrule your data. Great science! Let the data speak.

[@mikenewman4078]

Thanks for yet another carefully designed test series. I have a 3kw Honda inverter gen set which we take on the road with us, it does the job of running the caravan including air-conditioning walking away. A previous 2kw inverter gen set woeked! fine but it's 80cc engine was not any better on fuel than the 270cc Honda which supports your findings. I also own and maintain a 5kva diesel, neither genset cops your kind of workout, in fact both now have permanent battery chargers installed so they will start during a prolonged event. We don't see snow here or any temperature below 0 dec C.

[@rdcabal]

Good solid generator. One problem is conversion efficiency, a mere 16%. Run the gen indoors to get up to 80%. Put a hose on exhaust to scavenge that heat as well before venting it out. Remaining heat can be used to warm up air going on to the engine.

[@per-erikpersson9898]

That is the way to go, wasting all that heat from the engine.... Hooking it up to the water heater would be even better.

[@jondurr]

Thanks for doing this! I've always wondered how much generating your own power would cost. 5.9 kWh / $4.16 gal reg unl = 70.5 cents per kWh

[@USA-GreedyMenOfNoIntegrity]

That’s why it’s cheaper in the long run to buy more solar panels and charge controllers if needed. 34kWp and counting. Gen not needed so far at 38° latitude in the hypocrite belt.

[@MrOpenGL]

What is an hypocrite belt? Genuine question.

[@electrodacus]

That is actually quite an efficient generator. Still 70 cent/kWh vs around 2 cent/kWh for solar is 35x more expensive. I also heat my house with solar PV in a cold climate and I do not have a gasoline generator or any other sort of backup.

[@ulfg1409]

One more thing: fuel is just one of the costs. You'll be burning more money when you add generator maintenance (oil changes, spark plug, battery replacement, air filter...), wear (it eventually gets worn out and needs to be replaced by another expensive generator), using fuel in your car to haul fuel to the generator... Fuel should be the big cost, but everything else will add up to so much you need to factor it in.

[@mountaindan1840]

In my part of the hypocrite belt, we just went 3 or 4 days with essentially no solar. We have gone as many as 12. You either need a freight train loaded with money, or a generator. I had estimated 65 c/kwh at $3. This is nice to know exactly. Thanks David. Sizing a system to balance panels,batteries, and backup is dicey to me. 3-4 dollar gas can nail you quickly. And with minimum bills, benevolence is not on the agenda for the utility.

[@tincankiller6454]

Thanks for the video, David. Hard to beat those Honda Inverter Generators, efficient & reliable. Recently installed a EG4 Change-Inverter and for the money it's a good buy. A gas generator unfortunately is a necessity when loss of utility or off grid even with solar. My plan is to convert or build a wood gasifier generator. They are not very efficient as compared to gas, diesel, propane, alcohol etc. but having plenty of wood on property, already use for heat, and it a resource that is not reliant on someone else to supply but till that happens good ole gas generator is there. Stay Safe & Good Luck

[@BecomingOffgrid]

I would love to see a video on now this is done.

[@Sylvan_dB]

Those inverter generators are impressively efficient. Usually between about 20% to 90% load you are going to be pretty similar. I'm surprised the last run did so well!

[@mcg6762]

I wouldn't call 17.5% efficiency impressive.

[@MarcAntoineBvl]

@@mcg6762 ikr, I have 60kva genset at work that go up to 29% at 85% load

[@glyngibbs9489]

Thanks. Very interesting. The cold weather would have helped with the efficiency of the engine and the cooling. Recovery of the engine heat would help the overall efficiency no end. Looking forward to your next post.

[@SkyNoris]

This is great data! I've defiantly thought about adding a generator to my system. I've got two 100 amp chargers so it might be interesting to connect them both together and charge at 180 amps! Then compare the fuel price vs grid power. Thanks so much for your hard work and the crazy amount of time I'd take to produce this video David.

[@DavidPozEnergy]

Thank you for recognizing the time spent to make these tests and videos. It's a lot of work.

[@robertwagner3088]

At $4.00 a gallon that works out to $0.69 per KW for 5.8 KW; while significantly higher than the average utility this is good to know for those times when Solar needs some help in an off-grid application. Thanks David!

[@jeffreystorer4966]

Been off grid 2o yrs ,high output altnator and chargers,. Your battery bank will only accept the charge the battery can take ,I surgest 1 kVA EU Honda , with 15 amp max quality charger,or build DC Genset 4o amo car alt four stroke 2 HP , Honda 1 will run 8 hrs for half a gallon

[@familiant72]

I love it - you have to teach in MIT. They will love your accuracy explanation. Current at the end and the beginning of the cable is different due to losses 👍. Good job!

[@MultiTestPage]

Excellent test

[@jamesmaclean2]

Hi David This is great and your devotion to the task & to all of us is amazing ! If you have not done the Conversion Effecincy of Gasoline to Kilowatt hours it is easy with BTUs. There are 120,000 btu in the Gallon of Gasoline and 3,400btu in a kilowatt/hour. You got 5.8 Kilowatt hours so about 20,000 btu, gives ~ 16.6% conversion efficiency. Which is not bad for a small system as the Best Grid Systems are about 50% efficient... Plan B would be to Capture the Heat from the generator to heat your water.... Run the exhaust through a Plate Heat Exchanger. PS $3.50 gasoline for $.64 grid electricity is why we LOVE Solar. Great work Thanks James

[@M35a2guy]

It would have been interesting to see the run time results as well. Since the power output was roughly the same as measured by the shunt I have to believe the runtime was less as you increased the load. Maybe a shorter runtime is more advantageous for any number of reasons.

[@kevinthompson4690]

yes run time is very important given the results were almost identical for amperage. Can you run longer on reduced load? and still charge the same amount.

[@enigma9789]

@@kevinthompson4690 Why would you want to run longer and get the same amount? Why not run the max power for the shortest time if fuel economy is the same either way.

[@thephantom1492]

@@enigma9789 Engine wear. The higher the load, the more it wear it. But it is probably minimal, time (years) will damage it more than the extra load

[@andyg8758]

David, I have been watching and learning from your channels for years now. Thank you for all the good information that you provide. Is it possible to do an episode about adding wind power to your setup? Missouri Wind and Solar has been around for a while now, maybe they can send you a system to test.

[@DavidPozEnergy]

I wouldn't mind testing a turbine. However, my location is not very windy, which is why i never bothered buying a turbine.

[@juliogonzo2718]

Makes sense, I have heard that a generator will be the most efficient running close to max output. Efficient not in fuel burn vs time but fuel burn vs output

[@realvanman1]

There are a few important- but usually overlooked- things for anyone living "off grid" to consider. Since fuel is expensive, you want to get the most out of it. This means not only an efficient, slow speed generator set, but critically it MUST be water cooled so you can capture the waste heat. Even the best generator set rejects the overwhelming majority of the energy in the fuel as heat. Your test shows 83% wasted! You want that heat, or at least most of it. Heat up water and provide heat for your home with it. Also you want a small, low power generator set so it doesn't make more heat than you can use at one time. Ideally you'd time the operation of some of your loads so you bypass the inefficient charger/battery/inverter, and go straight to the load. If it will be charging a battery, you want to put together a direct current set that operates at battery voltage, to skip at least one step of loss. There are no small, low speed, good quality generator sets made anymore. This means overhauling a good old set, or putting together something on your own. Select a GOOD, small liquid cooled engine, such as a small Kubota diesel, and find a good generator for it to drive. Again, the key attributes are small, liquid cooled, slow speed. Diesel will be quite a bit more efficient too.

[@DavidPozEnergy]

I agree that a diesel is a better choice. This winter I purchased an MEP-802A, which is a 1800RPM diesel, liquid cooled. I've shown it in a couple of my videos. I've had this Honda for about 11 years and still use it.

[@WellsNursery]

Awesome test the generator didn't shut down at over capacity because its cold outside.

[@JC-li2xo]

First of all, thank you for doing the tests. I have wondered this same thing myself, and I am glad that it turned out to not really matter. I went back and looked at your generator. I see it is an older EU6500is, non fuel-injected like the newer EU7000is. I remember from some other sources that claimed the fuel injection didn’t improve the efficiency over a carburetor, at least a well tuned one. It would be interesting to see someone prove this in or out with hard data. On a different note, this is no doubt obvious to you, but may not be to others, that it will be more efficient to run loads directly off the generator if possible, rather than going through the batteries back through the inverter into the loads. In practice for example to also run a load of laundry or do something else task oriented when you need to top up the batteries, rather than run those tasks later from the batteries through the inverter. Assuming both that changing the batteries and running the inverters are both 93% efficient each by themselves, the end-to-end efficiency would be 86% efficient versus just running the task directly from the generator. Again, thanks for the video!

[@DavidPozEnergy]

Yes, it's true that if you are running a constant 5kW load (like a water heater) directly from the generator, then it's more efficient, saving the 13-14%. However, it's not as simple as that. Since our house loads vary, the generator doesn't see a consistent load. I have a previous video out where I tested the efficiency of my generator with a 1kW load (about 19% of the generator rating). I got 2.6kWh/gallon. Compared to the 5.8kWh/gallon in this video, that represents a 2.6kWh out to the load is 3.7kWh less than the maximum power/gal as measured at the generator. Or, a 59% loss. So, compared to running a 1kW load, charging the battery directly is far more efficient. As you can see, I can't say "running loads directly is more efficient". The answer is "it depends". BTW, I'm not arguing, I'm just sharing some additional thoughts that go into it. I find it a lot of fun to thing through these things and make spreadsheets.

[@thaddeustroyer]

@@DavidPozEnergy damn Dave... you are a smart mother#$%$er. Thats awesome. Also I didn't think you were arguing, data, is what it is. You were just presenting that. 👍

[@DavidPozEnergy]

Thanks Thaddeus.

[@justindarkcloud]

Do you have an inverter/charger that takes an ac input from a generator, can be set to take a constant input to power loads and send the rest to a battery to keep the input power constant? Would this be best for the example above?

[@jasonbroom7147]

Let me start by saying I really like alternative generation, storage and utilization of energy. I fully believe solar, wind and other renewable energy sources are how we will power our lives in the future. However, as you mentioned at the beginning of this video, there are times when those renewable sources just aren't reliable, so we have to be prepared with other solutions, including using fossil fuels, when necessary. Now, with that disclaimer out of the way, I think it is absolutely worth noting how much energy (roughly 5.8kw) you were able to put back into your battery bank with just a gallon of gasoline. When you consider that is probably close to 20% of your daily electricity usage, it's pretty remarkable that you could charge that much in a short time, using such a small amount of fuel. It's comforting to know that when solar isn't enough, just a few gallons of gas will charge up your system enough to keep the lights on and your household operating normally.

[@jimmurphy5355]

I was not surprised. Internal combustion engines are most efficient when the throttle is not creating a vacuum, and peak pressures and temperatures in the combustion chamber are achieved. Look up the Wikipedia article on heat engine efficiency for the details.

[@tracysmith7318]

Fuel economy vrs engine load (engine strain) . . I'd run at 80% and treat the engine a bit nicer. . . Might last longer.. run cooler, less stress, etc. Good luck. GREAT vid.

[@robgad2271]

I use a generator like this, change the carburetor to a dual fuel switchable carburetor fo4 under $40, make a HHO water to hydrogen electrolysis generator that separates the oxygen out, port the oxygen into the air intake with a small line, the hydrogen goes into the propane fitting with a gas appliance hose and regulator (like a propane BBQ set) and add a low pressure air pressure switch cut off at 15 psi on the hydrogen line to shut off the 12 VDC to the electrolysis chamber, and it needs to be in a indoor space like a garage with an exhaust ported outside, and this can be run as long as you need it. The system will cost under $300 to make, and only use gasoline when this is down for maintenance, and the engine basically only needs an oil change once a week. Running cost is around $30 a week, instead of $50 for fuel per day, and the engine runs better and longer on HHO. My HHO system is much larger, about a $700 unit, higher efficiency carbon fiber panels instead of stainless steel, and I run the hydrogen outlet through a bubbler cylinder with two gallons of gasoline to force hydrocarbon out of the fuel with the small bubbles, this combined with hydrogen makes a more efficient and more powerful fuel. It needs to be dried and filtered for any latent moisture, but it can be run through the 3/4" steel pipes to the home appliances as well lie the kitchen range, water heater and furnace, as long as they use an electronic ignition they don't waste fuel on a standing pilot and this is as safe as propane, but at 1/10 the cost, little maintenance and no calling for delivery or need to be in a municipal system with natural gas. The HHO also should discharge into a like with a 1 gallon expansion tank, it will fill and even out the on/off cycle as it operates to pressure up to the limit of the 15 psi NC pressure switch to keep the chamber as safe as possible. Do not use a dual output hydrogen with oxygen in the same pressure system, over 20 psi in voluble can spontaneously explode. Cheers.

[@nevermab]

Now I am curious what 60% and maybe 40% would be. I would have also thought the 80% would be the most efficient.

[@johnkirby6547]

Would love to see you try a 40, 50, 60 percent test, to see if different results

[@browsedeweb8834]

^ This.

[@ydnark83]

I am not surprised at all. That's a really nice generator and its energy output was the same because the fuel was the same, you just underestimated that Honda. Edit: Seeing as how the fuel efficiency doesn't really change I would probably keep it at 70-80 amps just to try and run everything a bit cooler get the most life out of that expensive generator. With a grain of salt bud, your obviously have more gear and experience than I do.

[@ewicky]

$3.50/gal divided by 5.9kWh/gal equals 59 cents/kWh. That's about 5 times the national average price of grid electricity delivered to the home. Although 59 cents sounds expensive at first, that is probably a bargain compared to upfront and recurring cost of being connected to the grid, especially for a home that didn't have the grid to begin with. And if you only need to generate from gasoline, say, 10% or less of your annual energy consumption, then yeah, no problem. Good work, David! I would be curious how that compares to other types/models of generators. Maybe you can borrow friends' open frame generators, smaller 120V suitcase generators, or even a new fuel-injected model for comparison testing. edit: just watched your suitcase generator comparison video, not sure how I missed that.

[@jockosboy17]

I would like to see this test with a non-inverter generator. I know inverter generators are more efficient but I'm curious what the difference is. Love the videos!!

[@TheBlibo]

Hi from the uk I have a similar hoda generator and while it is good and reliable and dose what it says on the tin they are not efficient I think I measured mine at 480grams per kWhr I think this is because it uses a permanent magnet alternator like many Japanese motor cycles rather than one with a proper active rotor adjusted by a regulator. But it dose have the advantage that if you change load suddenly or over load it the frequency won't droop only the voltage dose a little Keep up the good work

[@punto182]

I'd recommend a Bridge Rectifier as a Backup for Shtf - the tranformerless Pv Inverters will take a rectified generator input on the DC MC4 plugs in an emergency. 100amp 3phase Bridge Rectifiers, some are pretty robust and cheap

[@finlaybichan1275]

would be really interesting to repeat this test with your diy alternator generator you built in your last video!!

[@john0270]

Be interesting to see how a victron multiplus would do.

[@wictimovgovonca320]

Nice generator

[@seymourpro6097]

To get best value from the generator fuel try to find a use for the waste heat from the exhaust pipe. Something like 40% of the energy put into the engine as gasoline is lost from the exhaust as heat. If it's really cold then the LiFePO4 batteries will like some heat around them for best function and life.

[@BlenderRookie]

It takes a certain amount of energy just to overcome friction to turn the internal components of the generator. If the generator is producing more current in a given time period, then the less percentage of the total energy consumed goes toward overcoming the rotational friction. The generator undoubtedly ran for less time on a gallon of fuel as the output power increased. Meaning that the amount of rotational friction affected the total loss less with higher outputs. I suspect there's a close correlation between the ratio of runtime per gallon and the efficiency per given output load.

[@linkpatrick]

Great info, thx. Facial hair situation is looking gewwwd.

[@joec9680]

That is surprising results. That Honda inverter generator may be more efficient at lower wattage output in eco mode with the load low enough that the rpm is lower.

[@SI-lg2vp]

I have a 14KW diesel generator and it has a fuel efficiency chart to get the highest power output for the least amount of diesel fuel use. I will use that as a guide, and for my gasoline inverter generator I will use the 80%+ rating to charge the batteries.

[@greggmcclelland8430]

this is why overdrive is more fuel efficient in ice vehicles. you are lugging the engine back so more work for a given speed. In the case of a generator that runs a constant speed, the throttle is open more of the time with a higher load. So more air gets in and the fuel is burned more efficiently with more air. Honda absolutely makes the best gasoline generators. I think that model has fuel injection. If so then fuel air ratio is constantly being adjusted along with the throttle. Cheaper generators with a carburetor have a fixed fuel air ratio and the throttle controls the speed by only controlling how much air gets in and varying the amount of fuel.

[@DavidPozEnergy]

Thanks. This particular model (EU6500) is a carburetor. The current version of this generator is the EU7000, and it is fuel injected. They look almost identical.

[@defjamsgreen]

GREAT TEST . GOT BETTER RESULTS DURING SESSIONS TOWARDS THE END AT 100 AMPS . 👍

[@nuclearmaga9694]

very interesting

[@sciglassblower]

I totally agree with elec efficient heating like mini splits. But I don't want to use gas unless absolutely necessary. Winter: a propane heating system is much less Dollars to heat than a Generator to Elec heat, so we have a propane forced air heater. No generator this winter at all!

[@junkerzn7312]

I am not totally surprised, but I did expect there would be some differences and its a testament to the generator that there really weren't. Of course, it was pushing steady power the whole time, so "idle" losses would not be a factor in any of the tests. Still though, I'm imrpessed! The amperage is going to be the same along the whole wire loop no matter what the wire resistance is. The wire resistance will reduce the voltage only. That is, some power is lost due to wire resistance (power = current * voltage), but the amperage (and thus amp-hours) remains the same. Ultimately what is important here is to read the generator specifications, there should be a specification for the maximum efficiency point. Or a curve, or something. The charger should also have a specification somewhere (but generally it will be near the top-end of its capability). The batteries themselves... well, that many batteries, are being charged at well under 1C even at 100A, so their efficiency will not be affected at all for any of the amperages tested. -Matt

[@marcabplanalp8586]

My experience with generator power, The limit to output has more to do with ambient temperature, When the load is high the motor will shut down on high temp . This experience is from generators with liquid filled radiators

[@ralanham76]

It's good that the load can be matched to rpm

[@RubenKelevra]

How about adding a wood gasifier? It can heat up your home, heat additionally a buffer tank of hot water and generate gas to run a generator to generate energy to charge up the battery. :)

[@KevIsOffGrid]

Be nice to see a 50A/50% test - I run my generator at 50% rated when just charging, but have pass-through options for more power if there is more than just the charger running.

[@Fluxkompressor]

If you heat your home with electricity anyway, why don't you take this setup to the next level: Get a non-inverter, and maybe a Diesel generator. You already have a device with wich you can tune in the sweet spot of efficiency (the charger) So you can spare the losses of the inverter in the generator. Also a Diesel should be more efficient. And furthermore: Diesel is almost indefinably storeable Also try to use the heat from the engine somehow. Get a heat exchanger for the exhaust and heat your water that way. Duct the hot Air from the engine into your house If that thing has to run, you are probably in the middle of winter, so a little extra heat is nothing to waste

[@sirukin7849]

I was interested in the actual cost per hour. The Honda EU7000iS is a gas generator that uses 0.32 Gallons per hour, or ~1.21 Litres per hour. Current gas prices in Canada are ~$1.47/L. Let's assume however that you went for a full state of charge. Let's do some simple math: 20% = 6kWh 40% = 12kWh 60% = 18kWh 80% = 24kWh 100% = 30kWh Since 30kWh (100%) - 12kWh (40%) = 18kWh and if the Honda generator is used to charge to full power from a 40% charge, then you'll need 18kWh. If it takes 1 hour and 32 minutes to charge by 6kWh, then it's 1 hour and 32 minutes * 3. Or, around 4 hour and a half hours. 1.21L x 4.5 hours = 5.445 L. 5.445 Litres * $1.47 per Litre = $8 CAD. $8 CAD / 18kWh = $0.44 per kWh. Obviously you're not spending $0.44 per kWh all the time since you have a solar storage setup. However, the cool thing about this setup is what if you were connected to the grid? The Chargeverter can be turned on during off-peak hours when you'd be spending much less per kWh. You'd just need a transfer switch setup on your panel to swap to battery power during the day when solar is available and swap back to grid power to charge at night when electricity is cheap. This a is a ridiculously simple/clever setup. The SmartShunt is great. And the Chargeverter is dead simple, just plug into 120VAC/240VAC. Whether it's a generator or the grid, there isn't anything complex or complicated about the setup.

[@Imwright720]

I spent over $400 in fuel for just 14 days after a hurricane. It made me really appreciate FPL.

[@christophertstone]

That rating is probably at 20ºC, being colder it's probably able to output more.

[@loucinci3922]

Always interesting. I thought you would have different results. It seems the load was not very different as far as the genny was concerned. Wonder what the current was on the genny side of your setup. Assume it didn’t change much. Thanks for sharing

[@bumbarabun]

For 100A charge current at gen side is about 48*100/120 = 40A assuming batteries are 48V and Gen voltage is 120V. For 80A it is 48*100/80=32A

[@AndyFletcherX31]

I've got a 3.8KW inverter petrol generator which I use to boost my batteries via a couple of Siemens telecomms rectifiers. I get 7.5KWh into the batteries off a 5L can of fuel (1.5KWh/Litre). This works out at an overall efficiency of 16% which is reasonable for this sort of system. I've noticed that efficiency doesn't vary widely over a range of charge rates.

[@AndyFletcherX31]

BTW petrol has about 9KWh energy per litre. Small internal combustion engines are horribly inefficient.

[@gregben]

Another point to consider is the efficiency of the generator itself. One gallon of gasoline contains 34 kWh of energy (approx), and the generator delivered 5.8 kWh of electrical energy into its load (the EG4 charger) on one gallon of gas, so 5.8/34 = 17% efficiency. By comparison, utility-scale combined cycle natural gas fired power plants run at about 55 to 60% efficiency.

[@ozarkarky]

Good experiment and video idea .. try using wood gas for the generator. 🙌

[@armedmindset6778]

My Chargeverter came in today from Signature Solar. I sure hope it lasts longer than the other 48v charger I purchased from them. I wired up my propane generator last weekend in preparations for the new Chargeverter.

[@DavidPozEnergy]

Good luck with it. I hope it works well for you.

[@Giesis]

Great video. By the way where did you get the gas filler? Would love to get one

[@nhbountyhunter]

I did not see if somebody else mentioned this... 1 gallon of gasoline has a set amount of energy stored in it. Given the inverter and charger are pretty good due to being made well with good parts you will get 90%-95% of the stored energy from the fuel into your batteries. I'm guessing this would change with lower quality parts in the system but also willing to bet it will have the same result no madder the setup (meaning the same percentage of extracted energy will be put in the bat bank maybe 80%-85% with an inferior setup).

[@Deiphobuzz]

Get a watercooled generator and hook up a heat exchanger on it cooling circuit. That will increase your efficiency more than anything else you will try. Heating the boiler etc costs the most power, using the wasted heat energy from the ICE could heat your home if you store it in buffers.

[@thephantom1492]

I'm surprised but not that much. The engine efficiency drop after a certain point, but the engine is oversized so it can handle surges, and so it don't kill itself from constant max power usage. The alternator is mostly linear, the higher the load the most efficient it get. The inverter is mostly linear, with a slight drop at the high end The chargeverter is like the inverter, roughly the same technology, and is also linear and slightly drop at the end. Now, the engine being oversized is what saves everything: at max power you are most likelly close to max efficiency, which compensate more than the three inverters losses.

[@yvanpimentel9950]

If you mainly use the generator for heat you can use heating oil on a diesel engine is at least a dollar cheaper,a 5 KW diesel you get 2 hours and the hot water and even the hot muffler gases can be used for heat,it it's call cogeneration.

[@realvanman1]

Your generator will handle that overload due to the low ambient temperature, and the fact that it's a Honda, rather than a Chinese junker. It would not like that on a 100 degree day, and would likely trip off line. I would suggest trying lower power settings to find the lowest setting that still provides good economy. The engine will last longer, and all of the many electronics involved will enjoy lower stress and temperatures. The efficiency found in your test comes up to around 17%, which is in the range of typical. It is a shame that the engine driven generator generates AC (high frequency, three phase), which is then rectified, which is then inverted to 60 cycles, which your charger then rectifies and drops the voltage down to your battery voltage. Each step has it's own losses. If you had the engine driving a 48 volt DC generator, the efficiency would be considerably better. Though the efficiency might then get into the low 20's, you still don't want to use that to supply electric resistance heat. That's what you use the waste heat from the engine for.

[@DavidPozEnergy]

Yes, the cold air temperature helps. In my situation, with my solar and loads, I only need to pull out the generator during the winter. I've never ran out of solar energy in the summer.

[@roadtounemployment8736]

Great video as always David. Now with the new programmable chargeverter, I’m wondering if it’s more fuel efficient to run say a 2000w suitcase generator longer to achieve the desired charge over a 6500w one for a shorter period of time… previously I wouldn’t have considered this since the MPP’s don’t like to be under supplied on the line in, but now it’s possible to charge at whatever amperage is desired. As you say, the end goal being if you have to burn fossil fuels, it’s best to find the most economical and efficient way to do so.

[@DavidPozEnergy]

Check out my previous video where I tested a Honda EU2000 (suitcase) generator. kzbin.info/www/bejne/h3LSoKWcmceYnNE Personally, I'd want to go as large as practical. The practical limitations would be 0.5C charging rate of your battery bank, and what generator might be available to you. Then we could get into replacement parts, etc.

[@PatrickKQ4HBD]

​@@DavidPozEnergySo how many V/A/W is 0.5C for your battery?

[@stevemcmechan6444]

@@DavidPozEnergygreat video and testing I was surprised by the efficiency even at the higher amps still. Can you please show a video a little more about the Victron smart shunt to show whether it shows charge / discharge graphs to show how many kWh you can get when discharging down to a specific voltage eg 48.5v for example on your 51.2v packs. Will the smart shunt show you that with the charge and discharge curve graphs also? Cheers

[@yolo_burrito]

If you run the generator inside and route the exhaust outside you can recover the waste heat to warm your place.

[@kenwing6196]

Honda continues to impress...

[@offgridprep]

Wow long hair ! Didn’t recognize you lol great video

[@DavidPozEnergy]

Yeah, I'm trying out long hair for fun. Now that I'm out of the service I don't have to keep a high and tight.

[@ianpgeorge]

FYI .. to answer the title of the video .. generator is about ~17.2% efficient .. getting 5.8kwh of electricity from 1 gallon of gasoline (which has about ~33.7 kwh of chemical energy) = ~17.2% efficient. I might be interesting to see how this efficiency compares to a vehicle (car/truck) style system .. If a car/truck ICE is only 25% efficient fuel to shaft , and it's alternator is only ~70% efficient shaft to electricity .. it would still give about the same net ~17% efficiency ... 33.7 kwh in x 0.25% ICE x 0.70% Alternator = ~5.9 kwh electricity output ... ~5.8kwh in about ~1 hour is about ~5.8kw of power aka ~7.8HP. I would guess that some of the HEVs (prius and the like) would do the best .. as they were designed specifically to be more efficient power trains. Even if a vehicle style system is only equally as efficient .. gasoline to electricity .. it would still have a advantage in terms of fuel capacity (hours of available run time) over the smaller generator .. and because the vehicle is self propelled , it would have a convenience advantage in how easy it is to refill that fuel at a gas station by just driving the vehicle there , instead of transferring fuel to the generator , or moving around the heavy generator.

[@oldk4tz]

so the honda eco setting is great for constant current draws for efficiency but not for large surges.

[@DavidPozEnergy]

Yes, that's been my experience with it.

[@deuspax]

The efficiency is equal due to the fact that the charge power of 80, 90 or 100A is quite small relative to the capacity of your battery bank (30kWh). Only after you'd get over 0,5C (about 300A power charge) there is going to have first signs of drops in the efficiency curve - is not the case for your generator/charger which is able to get to a max of 100A

[@mcg6762]

State of charge not very relevant. The inefficiencies David is measuring is what is lost in the DC charger and the wires. Nothing else. There are additional huge losses in the generator both in the engine (which has at most 30% efficiency, probably more like 25%), and in the power head that converts from mechanical energy to AC electrical power. A gallon of gas has about 33.7 kWh of energy (the heat dissipated under optimal burning conditions). So the total efficiency David got was about 17.5 percent.

[@roblundy4203]

You mentioned the run time on the first test but not the others.Were they relatively close or was the run time shorter as amperage went up?If the run time shortens as amperage goes up you may as well go full out to get max recharge in least amount of time.

[@DavidPozEnergy]

the run times got shorter. The 70A test was the longest duration (1.5 hours). The 100A test was the shortest duration (1 hour).

[@evil17]

@@DavidPozEnergyso a fairly direct relationship we can see here between time & power for the same quantity of fuel.

[@jimmurphy5355]

Almost 6 kWh per gallon. Not bad at all for a relatively small generator.

[@Dudleymiddleton]

Great testing - and revealed a very consistent result thank you for sharing! ps what's the temperature where you are?, we in the UK have had a bit of a "cold" spell (so they keep whittlin' on about), but you got proper cold where you are lol!

[@DavidPozEnergy]

During the testing it was 20-30°F, so not bad. I have a video "short" on my channel from last month when it was -12°F.

[@rneal63]

It would be interesting if someone made a smart control system to run the generator just enough to get by until sunrise. I'm thinking you probably don't want to charge your batteries on gasoline to have 95% SOC at sunrise. I bought a Westinghouse auto start generator when they were on sale about a year ago. it would be nice to use just enough fuel to keep power going until panels are producing enough to take over.

[@bubbawubba2307]

Does the genny turn on by itself if minimum voltage is reached say 44.8 volts and engine cut off when voltage reaches say 52.0 volts??

[@paulnese1090]

Good Tests As far as cost per KW generated it depends on state location and type of generator. I live in Southern California with typically the highest gasoline prices in the country. A year plus ago it was as high as $7.00 a gallon. This week 04/05/23; it's $4.50/gal. btw - Here in SoCal my low usage Southern California Edison electricity rates are peak @ $0.49/KW-Hr. Several years ago I did tests on three generators. I don't recall what the price of gas at the time. Guestimate $4.00/gal 1) Harbor Freight Tailgater 2 cyl 800/900W @ $1.35/KW-hr 2) Champion 4 cyl 1200/1500W @ ~$1.00/Kw-hrs. 3) Sears Craftsman 4 cyc 4500/5000W I DID NOT TEST but I guestimate for some reason was maybe $0.75 - 0.90/Kw-hr. I would love to see a repeat test done with an equivalent size generator size to yours with a DIESEL generator. - Paul

[@DavidPozEnergy]

Awesome you did some testing on your own generators. The past few months, my local gas stations averaged $3.50/gal. I have a diesel generator (MEP-803A) that I'll be doing a fuel test on at some point.

[@shaun9493]

Wondering if bi facial solar panels would help your situation with cloudy days / snowy days. That's the standard for my old company for doing installs in Wisconsin.

[@thaddeustroyer]

The 80%rule is a good to live by with all things being the same. With that said it would be way better for your generator to run @80% ranther than 90 or 100+ for the longevity of your generator. The internals will run cooler and last longer at that rate better than anything higher. Actually if 70% works what's the harm with that? What I saw from the test was everything was very close to same results with the only exception being a little longer runtime (roughly 10 min) @ 70% Please correct me if I'm wrong, I am just noticing things in the video and really appreciate your tests because your videos have helped me tremendously. Keep up the good work.

[@DavidPozEnergy]

You are correct that running things below their MAX rating usually lets them last longer. That's actually what I was thinking when I said I'll adjust mine to 90 Amps instead of running it to the MAX of 100A. I want the chargeverter to last a while. Thanks for watching.

[@thaddeustroyer]

@@DavidPozEnergy good point, I was only thinking of the genny, buy the chargeverter should be run at a lower rate as well. Good catch 👏

[@volvo09]

In the summer I would not want the generator running at max load for extended periods of time, but in the winter I would be fine with it since cooling won't be a problem. The dead of winter is usually when you'd need to be charging from a generator more often anyways because of the lack of solar. In warm weather i'd taper back. But these were interesting results. I bet we'd see a difference on a lower end generator with a single speed governor.

[@DavidPozEnergy]

Hi volvo09, You are probably right, that summer might have more of an impact. In my situation, I have all the solar I need from March through November. I only need the generator to supplement during winter.

[@bimmers50e30]

I too am couris what the run times where. And maybe a 50A and 40A tests... Also a cheaper non interter Genset.... BUT even better, getting at the DC bus of the Honda 😍

[@scalty2008]

Its more effizient when the heat From Generator is also used. Additional, the 80% Rule should help for longer Living Generator

[@Stoner916sac]

This is how it is. It's an inverter generator LOL. 100% predictable. My HF predator is the same way. Can use two 80a chargers and it will put the same amount into my batteries, but faster or slower depending on if I use one or two. Chargers are about 93 percent efficient just like yours even though mine is 12v. I'd just go with the lowest amp charge that can get it where you need the SOC unless you need to charge fast for an emergency. It's nicer to the cells.

[@newsgeekus1216]

Interesting, love the tests and resulting data. So at $3.50 a gallon, your talkings 60 cents a kw. How many gallons do you usually use over the winter.

[@mcg6762]

Gas contains about 33.7 kWh of chemical energy per gallon. So the total efficiency was about 17.5 percent. Crazy how inefficient internal combustion engines are.

[@Mkiepert]

It’s has to be the honda generator… Nice video

[@grahamleiper1538]

Figure you may have similar overhead losses in the electronics regardless of different rates, so charging quicker would reduce the runtime, and that in turn reduces total overhead losses. Definitely see that with car charging.

[@isaacboersma4396]

You can take comfort in knowing that gasoline is not made from 'fossils' but actually from hydrocarbon which is very plentiful and one of the most efficient ways of producing power.

[@benkanobe7500]

I suspect you already know this but if not: You can go to your local General Aviation airport and purchase "100LL" which is ethanol free. Since you could need to rely on your generator and there is not an available propane conversion (I assumed you don't have a big propane tank in your yard) for your HONDA, the need to store gasoline in your generator and in reserve is there. "Ave Gas" stores well and is available if your state (like mine) does not sell ethanol-free gasoline.

[@DavidPozEnergy]

Thanks for the tip.