Viewer suggested upgrades - Answering your questions, Part 2

[@grantorinoaraucaria4487]

Great video, a galon of gas have aprox. 33,7Kw/h of energy, your conversion has 12,5% eficiency. Pretty good for modied alternator predator powered generator set! Thanks for Share!!

[@stanislav0803]

I found 42.9kWh in 1 gallon it's aprox 10.2% efficiency.

[@brianransom16]

That method doesn't do any justice be cause its an equivalency in raw power to compare to electric vehicles. ICE are roughly 20% efficient. Typically when generating power from a gallon of gas you get between 4 and 7 kwh. for a small generator this is actually not to bad. The fact its put together a garage is also outstanding.

[@flex-ranger2]

This has to be my favourite series of DIY on KZbin currently. You've done such a great job for all us hobbyists explaining all the little tid bits so that we can all have a crack at it. Thank you so much for all the effort!

[@DavidPozEnergy]

Your welcome. Thanks for watching.

[@srrandall88]

Please please continue optimizing this project as a series to get the maximum output... I'm enjoying the journey. Don't stop here

[@DavidPozEnergy]

Oh, boy. There are so many more projects to keep working on. This one will have to take a back-seat right now.

[@bumbarabun]

I think most efficiency would come by getting rid of that belt.

[@jacobcarlson4010]

@@bumbarabun: Not really. I think in the first video he said that the engine is 6 horsepower. If that’s true, that means the engine can do 4.41kW of power; and his tests showed getting about 4.2. Is worth chasing 210 watts of power? Probably not.

[@ckiottest5281]

@@jacobcarlson4010 Did the engine run for an hour? 4.2 kWh per gallon but how long did that take?

[@renatocunha6974]

@jacob seria kW/gal, não kWh a comparação. Que análises excelentes, parabéns pelo vídeo!! 👏👏👏👏 Eu planejo fazer um com automações de partida, desligamento e sensores para um gerenciamento na manutenção do motor.

[@RonLaws]

for kick-starting the alternator i think there's a couple of things you can do. The less obvious is to find a way to embed a perminent magnet in to the rotor somewhere so that when it spins it seeds the magnetic flux in the stater before the buck converter comes on and the closed loop takes over feeding the winding. A second and less invasive approach would be a small kickstart battery and a latching relay circuit Use a relay with a minimum closing voltage of 12v and tie it to the rotor winding circuit. Connect the buck converter output via the relay's 'normally open' side and the relay coil. Connect the battery to the normally closed side Connect the center contacts to the rotor windings. When there's enough voltage on the output to pull that relay closed it will disconnect the battery from the circuit and switch over to the buck converter, allowing the closed loop to take over feeding current to the rotor. As a bonus, You can cut the battery off when not in use with any kind of switch that serves as the 'ignition' switch for the generator so it doesn't go flat when not in use. as a small bonus, why not add a small trickle charger in there somewhere to keep the battery topped up =)

[@corborst4872]

Different approach same result. My home made 48 vdc generator/charger contains a 80's, 10 horse Hatz diesel engine and a permanent magnet hubmotor of an electric scooter/moped. I run the diesel at a slow 1400 rpm driving the hubmotor at about 650 rpm with a belt, put the 3 phases directly through a rectifier and like you did, the DC + and - through capacitors to smooth it out. I can make 2200 watts without stuff overheating, the hubmotor gets about 50C but I'm limited by the bridge rectifier that needs forced cooling at this point, but i can get a whopping 2.7 kwh out off 1 liter of diesel which is about 27% efficiency (One liter is 10kwh) and i was blown away by that result as it is an old NA diesel and some hubmotor i had laying around. With some duty free diesel i can charge my batteries for about 0,45 euro per kWh, which is not bad concidering that gasoline cost me at least double that per kWh....in Europe i might add where gasoline is liquid gold. It would be nice to make a gasoline genny with the same hubmotor setup, i would be curious how efficient that would be, the system would be much simpler, no need for a buck converter to generate an output, the amount of RPM decides how much current is flowing as the engine and hubmotor are loaded up once you hit battery voltage.

[@DavidPozEnergy]

I like it!

[@8180634]

I can't decide what's better, actually building out this Idea and testing it, or the quality of the video. Both are outstanding.

[@DavidPozEnergy]

Thank you.

[@highdesertdrew1844]

I built a generator like this probably 15 years ago, I used a 5HP B&S engine with a spare alternator from my Suburban. I kept it 12V because thats what the solar system at the cabin was set up for. One thing I found really helped was dropping the engine RPM, it allowed me to still pull about 40A at 12V, but I could run it at just above idle, it did a good job of juicing the batteries without blowing my eardrums out. I still have it, I'm going to rebuild it this summer, I really like the modifications you made as far as reducing vibration and I'm going to incorporate many of those features. Good series, liked it a lot, learned a few things.

[@DavidPozEnergy]

Cool. Maybe I'll run another fuel test at a lower idle.

[@Deveak]

How many hours would you say you got out of the block?

[@energydreamer5347]

@@DavidPozEnergy would you consider providing more details maybe by a series of video/s at a beginner level on the secondary components or electronic components that you have on this unit? Thank you!

[@midnightmotors7202]

@@DavidPozEnergy Great suggestion Drew, and great video, David. Most of the store-bought generators seem to rate their run times at half-load. The trade-off seems to be the slower you go, the higher the effiency. Of course this only works if you have the time - most people don't drive down the freeway at 35 MPH, even though we'd save on gas. Choices are good, though. Appreciate the work giving us the information to make better decisions. 🙂

[@charlesmoxley739]

I also built similar only using a 8hp B&S and a GM alternater charging 3 semi batterys running 3 2500 watt inverters barely above an idle ran my fridge heat lights ect and would only burn 5 gallons of gas at almost 51 hrs of runtime still have this setup for my backup Peace

[@MicahGallant]

Commented on last video. A lot of effort and expense here for a 48 volt charger. What i did was take a 'broken' inverter generator, where the inverter wasn't making power anymore. Used a bridge rectifier right off the AC windings to convert the direct output of the AC into 250 volt DC. Then Wired up MC4 plugs to go to my charge controller. To the charge controller, it just looks like a solar array. Generator was $200 broken, $50 for the bridge rectifier or so. So for a 48 volt charger, cheaper to reuse a 'broken' genny and use a rectifier than to completely build one

[@jackoneil3933]

Thanks David! Very interesting and informative test. In Alaska connected the exhaust of air and water cooled generators to a coil stainless steel and copper tubing, and immersed the coil as crude stack robber and estimated I was able to recover up to about 20% of the thermal heat energy from the engine. I mounted the generators above the heat exchanger coil inlet and plumbed the outlet out the bottom of a spray-foam insulated fiberglass or steel tanks so the exhaust condensate would drain out. On water cooled generators from 7kw to 600kw we installed coolant heat exchangers to the engine coolant system, removed the engine thermostats and used AMOT valves (Thermostats) in the heat exchanger loop to maximize heat recovery. Combing engine heat recovery with commercial exhaust to water stack robbers recovered up to 60% of the engine heat, so basically the fuel cost of our electric load provided heat most of our space heating. I was thinking a heat recovery might project might be interesting for viewers, and I would be happy to provide insights from my experience if needed.

[@DavidPozEnergy]

That is very cool. Do you have any websites, books, or videos you could link to? I'd like to learn more about the plumbing and try it.

[@jackoneil3933]

​@@DavidPozEnergy That was back in the 90's so I don't have a website or videos. Heat generator heat recovery hydronic heating in Alaska was somewhat common. I worked with a variety of hydronic heating and recover systems from what might be used to heat a small trailer from 2kw to large oilfield camps of several hundred men and megawatts of power generation, and depending on the scale of application you would be interested in I can provide information as the design depends varies greatly depending on the size of the system. The smallest system I did that might apply to a home system used a pair of 2800w air-cooled Honda generators. Basically, I welded threaded fittings to the exhaust outlets of the generators. As I recall the exhaust outlet of the Honda was about 3/4" diameter, and used 3ft of of 1.5" dia. flexible stainless steel tubing to reduce the vibrational stresses on the generator exhaust, insulated it with fiberglass high temp and connected the other end of the flex to, two coils of about 20' of 1.25 copper tubing immersed in a 350 gal steel tank that was about 3ft tall by 3ft. wide and 5 ft. long filled about 2.5ft. full ,and insulated with spray foam. I mounted the generators on a platform just above the top of the tank, and routed the flexible stainless tubing through a sleeve below the water level and connected it to the threaded fitting to one end of the copper tubing coil, and the other end of the tubing to a outlet in the bottom of the tank, so any condensate would drain out the end and into a drip pan. In the Alaskan arctic, in sub-zero temps there was little humidity so little condensate was produced, but in above zero temps you could see a gallon in a day that had had some soot. We used a locally produced gasoline that was more like white-gas / naphtha mix that had few additives and burned pretty clean. so the condensate was likely not too hazardous. The tank was open to the air and I used a small Grundfos pump (UPS15-58FC 1/25 HP 115-Volt 3-Speed Circulator Pump) on a thermostat at the bottom of the tank to pump hot water to baseboard heating element lengths with a fan to heat a small mobile trailer office, the generator delivered about 2000w of power for lights, a microwave, fridge, radios and a couple of 1500w electric heaters, and a few other things. The office was a well insulated ATCO trailer about 28ft long by 10ft wide that had about 3" of spray foam added to on the outside. The generators ran pretty much 24hours, and the system was pretty much self balancing down to about -25f, as the more electrical heating load produced more hot water. The grundfos pump was set to turn off when the tank temp got below 135f. below -30F we typically needed to use a 12V webasto gasoline heater to keep the trailer comfy We used glycol water mix but in warmer some applications water might be ok if you don't have to worry about freezing your coils or tank. I would estimate that the system recovered a about 2000 watts of heat from the combined generator exhausts when they were running at about 50% load. In warmer temps we only ran one generator. I'm thinking that you might be able to recover 1000 watt-hours or more of heat from the from a 4kwh run of your portable generator, and that would be pretty easy to calculate by measuring temp rise in a water tank. it might also be possible to plumb up some iron or steel water pipe for a direct exhaust heat exchange if you were sure to prevent exhaust leaks. If you want to chat about recovery systems and how to use AMOT water cooled generator recovery let me know.

[@northidahodreaming5657]

Your fuel economy result answers the largest question that I've long had. I seems that my 90-120 hours of winter battery charging by an AC generator is not such a inefficient solution compared to a possible DC charging option. Many thanks for all your work and sharing with us.

[@DavidPozEnergy]

Your welcome. I'm glad I could help. I had the same question for years and finally got around to testing it.

[@Chris_at_Home]

We have a remote cabin and have been using a Honda 2000 to charge the batteries when the sun isn’t good for over 20 years. With the eco throttle I don’t think any other generator will charge the batteries as efficiently because as the battery charge tapers off the generator runs slower. I set the charger in the inverter to 10amps AC max to keep from overloading the generator because you should never run a generator more than 75% of its rated output continuously.

[@williamvaughan1218]

​@@Chris_at_Home sounds like your using lead acid batteries?

[@incandescentwithrage]

Your charging solution *is* a DC charging setup, you just have the rectification and capacitor in the charger box, with a step down transformer.

[@ryanroberts1104]

I really like all the detailed info. If you're only taking 2.2kw from the alternator, you should get a smaller pulley for the alternator or a bigger one for the engine, then you can turn the throttle down and still spin the alternator at the same speed. You have more engine than you need, so it doesn't need to run at full speed. A smaller engine could make better fuel efficiency also...something like a 160cc would be good for 2.2kw. You should try playing with the voltage to the rotor, between that and RPMs you may be able to adjust it to run cooler or at a different speed with different voltages.

[@tarstarkusz]

There is a governor on the engine.

[@lesthompson5907]

that a good point dose it need to run so fast. if it was slowed by the ues of a bigger pully it as a possibility to save fuel by running it slower. been equal to the Honda generator by mens of . efficiency. their is serval different ways to carol of rotter sculpt with a Verica in the siystom. grat thinking son .

[@Psi-Storm]

I would go the other way. Run the alternator at 50+ A and direct air cool it with 12V fans. That way, you can run the current motor at a higher efficiency level. He said the motor had over 6 horse power, so a bigger or even two alternators, could also work better.

[@jimmurphy5355]

The alternator is 3 phase. The way that the phases overlap greatly reduces the output ripple . Even if you don’t use any smoothing cap at all, the ripple in the output is low enough that it probably could go to the charge controller as is.

[@kellyj1464]

Maybe, but why risk damaging a pricey charge controller when capacitors are so cheap? If nothing else, the internal monitoring software will not be expecting pulsing input voltage and may become inaccurate with some noise. Even with external measuring devices, the system is easier to measure with less ripple. I don't see why anyone would go through all this trouble just to save a few bucks on a capacitor.

[@teardowndan5364]

@@kellyj1464 The 1000uF capacitor feeding 25A to the load is a 25V/ms slew rate when the 85VDC system already has only about 10V of peak-to-peak ripple at 500-600Hz which is 1.5-2ms. If you put an oscilloscope on this or simulated it in something like LTSpice, you would find that it makes no meaningful difference on voltage waveforms. What the capacitor does do though is wreck stator and diode current waveforms.

[@williamvaughan1218]

Ford states these alternators as a 6 phase. You have 2 3 phase outputs.

[@Greg-io1ip]

One note David: If your gas stays cold, the motor is more efficient. Especially if it has a fuel injection CDI ignition instead of carburetor. But nice project. And practice

[@linuxguy1199]

@@teardowndan5364 Dude 10V of peak-to-peak ripple is pretty bad, that's 10% of the output voltage. If it means a little bit of current spikes that's fine, with the high ESR of a big electrolytic like that a little 100A current spike for half a millisecond won't do anything anyways. Those bridge rectifier packs are usually good for 1500A spikes, 200-300A continuous. But yeah, really he should've made a resonant LC network to perfectly cancel the ripple without causing huge current spikes.

[@philherb3843]

When you mostly need this setup in winter, it would be nice to gain the heat, too. Even when you only can gain half the heat and the other half is lost, it would double the efficency. Maybe a generator with water cooling and putting the heat in the house water heating system? Maybe an enclosure with a air/water heat exchanger and another heat exchanger in the shop?

[@marklewus5468]

Great videos, just a few comments from an old engineer. Small engine carburetors only provide optimal mix for a single RPM, load, air temperature, air density, and fuel variant. Fuel injection (like newer Hondas) would substantively improve fuel efficiency. You might be able to get an FI kit, or set one operating rpm/load for battery charging and jet/set the carb optimally for your RPM/load point and altitude, and adjust seasonally.

[@TheBry_Guy]

wish i lived closer, I'd loan the channel my eu7000 for testing. basically the same as his EU6500 but fuel injected.

[@SaltGrains_Fready]

He should just use a Honda engine from a used generator. I thought about that also. This HF engine is only 2/3 the efficiency of the Honda engine

[@davidgrea]

Loved it and great for learning now get a small diesel engine and do it all again with 2 alternators

[@petevenuti7355]

How you got cookie monster?

[@1981dasimpson]

it would also be interesting if you altered the buck converter voltage and see the resulting watt output

[@samvalentine3206]

With regards to the flexing that we see of the motor plate with the mounted alternator, it seems that a piece of angle iron going perpendicular to the angle iron alternator mount may reduce that flex. Adding some more angle iron to make an "X" or a cross of angle iron in approximately the middle of your plate. I'd bet that would stiffen things up so you wouldn't see that flexing we see in the video due to the harmonics. All in all a GREAT project, one that I think many of us (myself included) have thought of "what if I built this?" and you did! Even though it's not as efficient on a gallon of gas when compared to the Honda inverter generator, not everyone can afford to put down the funds needed for a big Honda inverter generator like that. As you said, folks may have a spare engine and alternator lying around in their stash. Thank you, David!

[@DavidPozEnergy]

Thanks for the nice comment. I appreciate you watching to the end. After each version, there are more modifications to be made. I wish I had the time for all of it.

[@lasersbee]

Was going to mention the Angle iron Fix..👍

[@TheGulnawaz]

​@DavidPoz hello, any plans on testing some Chinese lithium ion storage battery brands. Like Bslbatt, narada, gsl, bluesun. Looking forward 👌

[@joshanderson1019]

One thing that I learned by building these is the gearing for the engine and alternator needs to be about 1:1. That pairs the engine perfectly with the alternator, since it doesn't need to be spinning that fast. The alternator will run significantly cooler and your engine will use less fuel. The reason alternators have electromagnets instead of permanent magnets is because it drastically increases performance at low rpms. Since you are requiring 48v from a 12v alternator, you might still need to spin the alternator faster, but not likely. You should put a small load on the alternator (like 10 amps) and lower the engine rpm until the voltage starts to drop then speed it up just a bit. That will get your alternator at peak efficiency and you can run a gearing calculator to see what gearing you need. You could probably even get away with just running the engine at the speed that you had during the test mentioned above, since the governor will maintain that speed as the load increases. I love your videos and am glad to see you make some of the things that I make for fun too.

[@casemodder89]

if you load it with 10A you'll find the rpm for 10A. on higher load the rpm will sag much more and the dropping rpm will drop output drastically. you'd need a current and voltage sensing circuit and a servo controlled carb that would lower the rpm on slight loads and rise it on high loads.

[@Tumbleweed5150]

@@casemodder89 Since this is designed purely for charging a battery bank, the load can be the same all the time. The same rpm will work just fine. No need for the expensive carb. The point above is to find the Amperage you want to feed the battery bank, then figure what rpm to run the engine at to achieve that as efficiently as possible, I believe.

[@judahschwarz3552]

Alternators use electromagnets so they can adjust the output current based on the varying load rather than having to change the rotor speed

[@demoniack81]

@@Tumbleweed5150 Running ANY internal combustion engine at anything other than full throttle at its peak torque point will always result in big efficiency losses. A piston engine has comparatively very high frictional losses that are largely independent from load. What you want to do is get the maximum amount of energy out of any single piston stroke, because every time the engine makes a stroke you incur those losses. Since energy (work) in physically is defined as force times distance, and we cannot change the length of a stroke (for obvious reasons), all we can do is look at the force. The force acting on every power stroke is linearly correlated with the torque (torque is just force * distance between the connecting rod bearing and the center of the crankshaft). Given all that, in order to get the maximum energy out of the fuel you need to look at the torque curve (not power curve), set the governor at the RPM where said curve peaks, load the engine up to the point where the engine speed is just beginning to sag, and then back off again just a tiny bit. That's the maximum amount of load you can put on the engine while keeping its speed in the highest efficiency band. If you wanted to go further that that you should start looking at optimizing the cam profiles or otherwise changing the combustion characteristics of the engine itself, but that's most likely beyond the scope of an amateur building a diy generator like this. One thing you could do is get rid of the carburettor and run the engine on LPG/propane. With a fixed load it's easy to just pipe a constant stream of gas into the intake without having to come up with complicated gas flow regulators. LPG would mix with the air much better than gasoline, providing cleaner and more efficient combustion. The only issue I see with this is that it would change the combustion characteristics of the fuel and may shift the torque curve slightly, but you could adjust for that by performing a couple test runs with +- 100RPM from the peak curve. If you find that your efficiency goes up, try moving another 100RPM in that direction. If it drops, back off 50RPM. Repeat until you find the new peak. Another possible issue is that LPG burns hotter than petrol, so you'd have to keep an eye on your engine temperature. Edit: also the optimal ignition timing on LPG may be different, even with the same compression and cam profiles. Yeah basically, optimizing combustion engines is complicated, there's a lot of variables at play. There's a reason why car manufacturers spend billions on R&D every year. However, I do believe that in the small engine space there is probably room for a dedicated enough DIYer to do better than the manufacturers themselves. Consumers don't really care that much about the fuel consumption of their little garden tools, so the manufacturers are not heavily incentivized to optimize for it.

[@TheXxRenzxX]

For almost all buck/boost converters, the two negative connections are actually untouched/commoned. This is because these circuits modulate voltage on the positive side in reference to this common negative rail. To double check, just check for continuity between -IN and -OUT on your converter. Hope this helps!

[@liam3284]

Given the voltage ratio, I expect a two active switch buck with a transformer.

[@mckenziekeith7434]

@@liam3284 even if there is a transformer, in- and out- may well be connected internally to simplify voltage sensing etc.

[@coryr6359]

Very informative. If a person was looking for a good cost saving approach, there isnt much better than this!!

[@Daniel-Johnson]

I love the Ingenuity man and just getting to do Hands-On projects like this are so fun it's easy for anybody to go out and just buy something to do the job and that's totally fine I'm not against that if you are not comfortable trying to build something like this by all means don't there's nothing wrong with that but it's so much more fun to try and build it and make it work yourself the end result is always much more satisfying sure you might not use that DIY unit you built all the time or maybe you will but the point is you had a lot of fun building it you learn you discover through trial and error and it just makes it all so worth it great job love the videos on this!

[@DavidPozEnergy]

Well said!

[@Jimmeh_B]

@@DavidPozEnergy This was a REALLY cool project man! Kudos! I know I'm late to the party, but I have a question. When you were measuring the capacitor current, were you measuring AC amps, or DC amps? Potentially, especially if you took the measurement in DC, it's probably nowhere near accurate? Also, depending on the frequency of the ripple, and whether or not that meter reads in RMS, that 180-190 mA may also be anywhere near accurate? If I were anywhere near you, I'd offer to bring one of my Oscilloscopes over to have a look at the output waveform, just for shoots and giggles. Either way man, very cool project, loved it!

[@SirBlmp]

Next steps.. Super caps to charge field windingings on startup and Remote start lol

[@lorenray9479]

Another fun journey into better understanding that which can not be immediately seen, but immediately felt lol

[@craignels]

I think an ohms check will confirm that the buck converter's input and output negative terminals are tied together so that other experimenters may indeed be able to use the internal diodes. Great follow up video.

[@craignels]

But in your case external diodes are still a good call. Newer alternators use diodes that avalanche around 20 to 40 volts. Finding this spec on an unknown alternator can be tough so external diodes remove any doubt.

[@TheMacroSlacker]

@@craignels A safety feature I suspect

[@JbVest]

Yes a part two!! I literally built the same thing with a few of the same parts. It works pretty good at higher throttle I can pull about 2,800 Watts found a little constant current adjustable regulator where I can adjust the current going to the field windings so it doesn't bog down The motor too much. Works great. I found about 2.1 amps to be a good output for my alternator. It's literally just an alternator from an '87 mustang

[@brennansmith1381]

It would be interesting to see how a permanent magnet alternator would perform in efficiency and temperature.

[@InssiAjaton]

The output control depends on control of the rotor excitation. With permanent magnets you would need to figure out some other means of control. Or oversize the charge controller to potentially handle hundreds of volts.

[@ericdelevinquiere9902]

Permanent magnets could give you a better efficiency, as used in wind turbines, no waste of energy in having to input current to get the thing going. Your controller of course needs to be able to handle the voltage output and could be more costly depending on the specifics.

[@ryanroberts1104]

It would be more efficient, but probably not by much. The rotor electromagnet is using 60 watts. At 2.2kw that's only 2.7% of the output.

[@beforebefore]

12v @ 5a loss, so 60 Watts lost energy - as compared to a permanent magnet alternator. Have you tried reducing the Stator feed voltage? High stator power is typically only needed at low RPM conditions, and will cause more magnetic drag and energy loss at normal RPM conditions. That DC to DC converter is probably adjustable, most are. You are also wasting power by using passive silicon bridge rectifiers... about 120 Watts lost, since each diode loses about 1.5 Volt during conduction, and you always have 2 of them in full conduction. 40 Amps x 1.5v x 2 diodes is 120 Watts. Using synchronous rectification would reduce that to about 10-15 Watts, but would be expensive.

[@dantronics1682]

using a controller you get a flat output vs speed where as using a permanent magnet you get a means(bell curve) output. if you are trying to figure this out then look for car dynamo outputs for autos pre 1978

[@dariuscalitz9704]

Thank you very much for the follow up video, and thank you in general for making video's, here in South Africa we have multiple times of power outage per day, thanks to loadshedding from 2 hours to 16 hours a day. So doing stuff diy really helps especially when solar pannels is always out of stock and inverter generators is quite scares aswell, but thanks again for the follow up video.

[@Jay-Leigh863]

Hi Darius. Im also in South Africa and these rolling blackouts that get called loadshedding is the exact reason I'm here!

[@chrisdekock8864]

Another south African here! I knew some Saffas would check this out. It is a kak spul there. Mom is still left there, she refused to leave. I packed up in 2019 and came to USA. Mom is off grid with 7kw lithium and 5kw inverter and 1800l JoJo. Just sponsored her with some ecoflow goodies and solar panels for the caravan trip to Scottburgh. I am off grid too, my yacht is on solar power and only needed to run the generator once in last 20 days due to a 5 days of rain. I have a 100amp alternator on my 55hp Diesel engine, and a 20amp and 40 amp DC to DC charge controller for my 6kw of lithium on my sailboat. I can charge all 6kw with 3.5 liter of petrol in the Honda generator in 8 hours. In conclusion of this video, Not worth the effort and cost to go directly DC charging on another engine, although a single cylinder diesel Lister would be lots of fun to play with

[@junkmail4613]

Back in 1965, I modified the 55 amp alternator on a 55 Dodge station wagon. I setup 12 to 14 volts on the stator field and got out 150 volts at 4000 engine rpm, gauging pulley ratios from 1955 memory, likely 3 to 1 so 12000 rpm. The 1/4 hp variable speed universal brush motor on the drill worked fine except that it wouldn't turn off. Had to unplug it. What did I know, I was just a kid. Anyway, for short term use, 50 amps times 150 volts would be 7500 watts possible or about ten horsepower off that car engine. Half that 7500 or 3750 would be going into the load and the other half would be lost into the field windings. I'm fairly sure your setup was much more stable than mine was. That phone measuring and adjusting the power rating was really cool. Not available back in 1965. Anyway, your alternator was prepared to operate at full capacity in a much overheated engine compartment, with safety margins on their capacities as well. You said yours was a 215 amp alternator, and you ran it at 50 amps and the field ran up to 100 deg Centigrade, but the field rating was 160 deg C, my guess might be linear relationship so 50 amps times 160 deg divided by 100 deg might ask ya to test long term monitoring at 80 amps, certainly within the 215 amp device capacity. I'm also thinking Amperage squared times resistance would suggest 1.6 squared or 2.5 times as much heating, but at higher temperature you have more dissipation. Maybe change motor pulley size to get it up towards 12000 rpm as rated and get more alternator internal fan cooling. (also you'd have more max voltage, not needing as much current for the same power rating. You could certainly draw more power out of that gas motor with your system) Looks like great fun, thanks for letting us watch your exploration!

[@texan2560]

Great project and video. Maybe fab up some small fan and mount to the alternator to pass more air over it and keep it cooler.

[@jjclarkson3261]

Excellent video, with plenty of details and VOLUME LEVELS to avoid blowing out eardrums. Liked and Subscribed!

[@DavidPozEnergy]

Thank you for noticing the sound levels. It takes a lot of time to adjust them.

[@linmal2242]

Great job David! You could also put some solid rubber wheels on it (two fixed and two pivot with locking brakes) and a handle so you can move it around easily if you need to. Also a mesh guard on the belt to stop fingers from getting mangled!

[@charleswhitehead7441]

We fit high output alternators to large yachts on a regular basis. Most alternators are actually very inefficient, something like 50% whereas the alternator for 110 or 220V is much higher >80%

[@georgemorris7947]

Hello! I'm really writing to say how much I enjoyed both of your videos on this subject. Thank you! As regards the ultimate limit to the power you might draw from your alternator I suspect you could go very much further using a really large exciter current. Of course all that power has to go into the alternator mechanically, in your rig through the belt: I think the ultimate limit there might lie with the alternator shaft bearings because of the tension you'd have to put on the belt to transmit that level of power! Looking forward to more and all the best meanwhile! Cheers, George Morris

[@linkpatrick]

I feel like there are so many better ways to do what you're after. But you do this anyway. I love it. I also appreciate you showing all the things that you do to "make it work." Like the washers and the exposed screw trimming.

[@rpasco9352]

One more suggestion: The belt -will- stretch with use. Why don't you add any typical alternator idler puller/belt tensioner that will always maintain the optimum belt tension ? This will also act as a shock absorber of sorts and reduce vibration.

[@mattnbin]

There is an old guy living of grid with a similar set up. He gets 10 hours from a gallon of fuel. Running alternator at way slower speed. 12v 30amps charging. His channel is rbodell. All the best to you. Great work!!!

[@tonyshipman257]

David, Thank you for sharing the outcome of the mods. I'm glad the input was helpful and worked. Take care, Tony

[@toma.cnc1]

I was wondering "why did i open this video" till i saw your picture!!! Cool look, and nice video, as usual. Thank you.

[@johnhknapp]

I made the 12 volt version of this on a solar trailer I made. It uses a Victron smart battery monitor to signal a Deep Sea gen control to start my predator engine when voltage falls below a certain point. Can't wait to build 48 volt version! I was inspired by this build.

[@Tumbleweed5150]

Nice looking set-up, and it WORKS! I've known several folks who used a similar set-up to charge their 12V systems. We call them "poor boys", short for poor boy generator, because we couldn't afford the real thing. LOL Thanks for doing these two videos. My neighbor and I both run 48V systems for our off-grid homes. So far, we haven't had to run generators because we get a lot of sun, but this might be a good thing for us, in case of a blackout at night, to put in enough sun so that the inverter will start powering our refrigerators asap. I do have a Honda 6500, but it needs to be taken in to adjust it, as the Voltage isn't right coming out. (I think a neighbor screwed in all the adjustment screws as a joke). I could get the Chargeverter from Signature Solar and use that, once I have the generator running properly. Just haven't gotten the cash saved up to take it into the shop. Thanks again. Love your channel!

[@therobb5738]

I run a 750w DC to AC inverter in my SUV. It's a huge advantage and lifesaver, seeing as how I can use it for daily use and also emergency backup. I can run grinders and vacuums and damn near an AC or microwave. I live in a camper so most of my house runs on DC as it is; but having those few additional AC backups makes all the difference when storms blow through and knock out the power. I still have full power, plus chainsaws to help the neighbors.

[@andrewmutavi590]

Watching this n methane n bio diesel come to mind,in this day n age u simply can't overstate the importance of self reliance when it comes to energy production

[@TheVillainsProjects]

I really appreciate you comparing the DIY to the off-shelf version, and would love a more comprehensive comparison, maybe a short list of pros and cons of going each way for a generator.

[@Rickmakes]

It would be cool to see you make modifications to this to meet or beat the Honda's performance.

[@JbVest]

Also vibrations are still one of my issues that I'm trying to resolve, watching video now

[@jakes1292]

This is a great addition to the community conversation. Thanks David!

[@gabrielpadilla2583]

IT WAS fun watching you go through all the trouble but it look to me like you tried to reinvent the wheel. lol there are lot of different ways to achieve better results with less costs and risks . but it was very educational and fun for the people with less understanding of electronics and the ohms law.

[@andrewlindh5047]

You need a fan on the alternator. Many alternator just use a small fan behind the pulley for forced air cooling. This would allow you to extract more amps and run cooler which should be more efficient. Also, as you stated before, direct drive rather than a belt.

[@DavidPozEnergy]

Check out 12:15

[@andrewlindh5047]

@@DavidPozEnergy Missed that... Thanks.

[@noanyobiseniss7462]

I like the way your using the scientific method to optimize even if you didn't know that's what your doing.

[@hardbrocklife]

Definitely one of the best series for a DIY generator. I want to build one with a cheap Chinese clone diesel engine.

[@catman6605]

If you get an engine set up for electric start, you can use the charge circuit from the engine to excite the alternator automatically when started and ditch the buck converter and having to use and external power supply to trip the alternator

[@pieceworkstudios]

Just finished part 1 and I'm here for it 👍. All chores on hold! 😂

[@DavidPozEnergy]

Thank you, I appreciate it.

[@pieceworkstudios]

@@DavidPozEnergy you're very talented and creative. Thanks for explaining things even the types of tools you use. It's very helpful. Sometimes I'll see someone use a tool that I know I could benefit from but haven't seen it don't know what it's called.

[@MiniLuv-1984]

Nice demonstration David!! If you wanted to measure the conversion efficiency of the alternator + charge controller, you could replace the petrol motor with an electric motor, measure the power required to drive the electric motor and then see how much power you get out of the alternator (before the charge controller). I think the 100oC on the alternator amounts to a substantial amount lost energy going to heat. You will need to factor in the efficiency of the electric motor, but I suspect that will be greater than 90%. Mayby part 3?

[@jimjones7821]

an electric motor is NOT 90% efficient

[@carlomilord1374]

You kill it! good job. I cant wait to make one.

[@mckenziekeith7434]

This is a great video! You could try using a smaller field voltage. This will reduce losses in the field coil. As long as the output voltage from the bridge rectifier is greater than the battery voltage, you should be able to charge the batteries (might need a different charge controller). This may increase the current in the stator winding, so maybe it will not be a net win. I am not sure. It is just something to try. There may be a specific field voltage that produces maximum efficiency is what I am saying. One other thing you could do is attach a motor controller to the three-phase output (instead of the diodes) and operate the controller in regen mode. That should bump up the efficiency a bit. But there is a lot of learning curve with motor controllers.

[@GoingOffGrid101]

great test, thats very interesting that it was less efficient.

[@DavidPozEnergy]

Thanks.

[@outoftexasRev7v9]

If that I may: you, Sir, definitely have talents that are worthy of the Showalter Brothers building an advertising platform around you. I mean only the greatest respect when I say that; you have the enthused appeal and adept knowledge to be the DIY equivalent of a cross between Bob Vila and Bill Nye with a touch of mr. Wizard.

[@DavidPozEnergy]

Thank you. Those are some of the greats.

[@mikemoore466]

Nice. Now that’s they way I had it in my head that it should look like.

[@dantheman6698]

how well would the setup work if you used the treadmill dc motor ? last time the engine you used was under powered, that 212cc should do much better.

[@ravenbarsrepairs5594]

To reduce vibration, you should also mount another rubber mount under the center of the plate. As is, the torque transfered between the motor and alternator will flex the center of the plate downward.

[@oliverer3]

I've been wanting to design a custom hyper efficient 3-phase inverter battery charger for a generator project like this for ages and this video might be what finally pushes me over the edge. If I pull zero punches and use every bit of EE knowledge I have getting >98% efficiency between the alternator/generator and battery would be fully possible. Can't get rid of the inherent inefficiency of IC engines though or what is lost from the internal resistance of the battery.

[@keithcress1335]

That was a blast! Thanks David. Man, any scheme based on diesel or gasoline sure costs a boatload more than the utility rates these days. Essentially a $1 a killowatt hour instead of 10~30 cents a kWhr. I guess now you should get that methane digester going? 😀

[@TheBry_Guy]

or a big hamster wheel and put the kids in it for an hour a day :)

[@KuntalGhosh]

So what if you use the permanent magnet alternator from a inverter generator. Without using the 120v inverter. You can hook the 3 phase stator to a rectifier and capacitor then to the pv input of your chage controller. It will remove one power inverter out the picture and should increase 10%-15% efficiency.

[@beyondboris]

David, I loved your project. By any standard it is a success. Reading the comments obviously you can optimise it in many ways, however, what strikes me as your project's greatest strength is that it is all a made from available parts. Arguably you could repair/keep this thing going in a zombie apocolypse! Anyone can go and spend $3k++ on something sophisticated, but can they repair and keep it going if their life depended on it. As a pragmatic engineer I say, if that was your goal then you 'hit the nail right on the head'. Keep up the good work.

[@DavidPozEnergy]

Thank you, I appreciate this.

[@johnvasko4035]

I built one 20 years ago using a Kubota 4hp water cooled diesel signboard engine, a 100 amp gm alternator, and a 12 volt three stage marine charge controller. I built an outdoor cabinet for it with a cooling fan, an electric fuel pump and a 12 volt solenoid valve controlled by a Intermatic 6 hour spring wound timer. The timer controls the solenoid valve to cut off fuel to the engine to stop it. I had to build an external bridge rectifier on heat sinks because the alternators built in one would desolder itself and fail. I'm getting 5kwh/gal of diesel @ 1600 rpm/55 amps. Very quiet, long life. 5 gal fuel tank. 8h/gal run time.

[@rpasco9352]

Ingenious ! 1- However, pushing more double the current out of the rectifier diodes will certainly make them fail ! They -must- be upgraded. 2- Rewiring the rotor windings from a 'Y' configuration to a 'Delta' increases the current, but, since the output power of the alternator is fixed, the output voltage has to be less than it was before, just like a transformer. We never see a reading of that voltage, so how do you know it is high enough for the inverter ? 3- The original alternator configuration had the regulator feeding the rotor coils the voltage first from the battery, about 12.8 volts, but once the alternator starts it will be fed its own output voltage, about 14.4 volts, -not- the 12.0 volts you are giving it. How do you know your 12V power supply is actually pushing enough current into the rotor coils ? Is 5 amps enough ? Are you at or past that power supplies limit ? It should never exceed about 80 percent of its claimed maximum.

[@benhoffman7672]

David, thank you for the follow-up video. It looks like you are good as far as ripple current into the capacitor. Was the charge controller connected to the generator output when you took the ripple current measurement of the external capacitor? If it was I would still be interested in seeing the ripple current into the charge controller itself (if it wasn't connected at the time of the measurement you are probably alright). Since you were limiting the output of the system due to the temperature rise of the alternator, your engine is probably a little bigger than you need, so that probably reduced your efficiency some. If you were to run the experiment again I would recommend increasing your output by 10% and seeing where your efficiency is then (if it increases then your motor is a bit too big). Thanks again for these videos, they have been very interesting.

[@aatirehrarsiddiqui8894]

Electrical Engineer here. Top video mate. Subbed. Some ideas I would love to see. - If you increase the excitation a bit to see how far you can take it - If possible hook up the AC output voltage to an oscilloscope to see how clean the AC waveform is. The frequency, shape of the waveform that kinda thing. I am curious to see if you can use this setup as an AC generator without all the DC rectification stuff and run stuff like lights fans or maybe even electronics like computers if the AC waveform is clean and stable enough in terms of frequency and voltage.

[@mikesgarage394]

An additional reason to use external diodes is that many modern alternator use avalanche diodes (like a zener) which avalanche @ ~26v which would limit output and actually destroy themselves. They are basically surge protection for the car electronics.

[@MarkPrince1317]

Brother you should try wind generator Best regards from Philippines 🇵🇭 and thank you very much for your informative videos

[@sidswift4709]

Hello David, Just a suggestion related to your heat concerns on the alternator, how about adding a fan blade of larger diameter to the pulley of the alternater to add additional cooling effects for your unit ,of course you'd want to keep things safe so you could use a piece of duct( like a small section ) of say , clothes dryer ducting to protect fingers from contacting the fan blades

[@ckiottest5281]

I just ran an efficiency test charging my newly made LiFePo4 48V battery I made. Running a Westinghouse 8.5 kW generator into my Sungold inverter I managed just over 4kWh per gallon which is on par with what you ran here. The inverter could only load the generator to about 2700 watts (50 amps charging). I'd like to try with a smaller generator and see if I could come closer to your Honda results. An automotive alternator just isn't that efficient but like you said was a cool project.

[@KC-vp7wn]

I think the next test that I would do is to control the amount of current to the rotor . Do you need 5 amps driving that rotor? Probably not, you may be able to lower that rotor current and still get a good amount of power out and you may find that you reduce the heat of the alternator. Just a thought. Great video!

[@marklewus5468]

As another viewer mentioned, permanent magnet motors make great generators. Using a Neodymium “outrunner”brushless motor as a generator would greatly improve efficiency. Alternators are around 75% efficient. A brushless “outrunner” would work at the RPM of your engine with perhaps 2:1 pulleys (7-8K rpm) and can approach 95% efficiency plus a much smaller fan load. However, a 2 kW brushless motor will not be cheap.

[@DavidPozEnergy]

Thanks. I'm planning another project with a PMA, so it will be fun.

[@rossbrigolimusic]

Great work! Got a couple of suggestions, try a bigger buck converter and see if you can get the fuel efficiency better with lower rpm. Another thing is that buck converter may not last long with all the vibration. You could mechanically isolate it from the engilne or soak it in silicone.

[@SuperBrainAK]

That was a really well done experiment! Thanks for the tutorial video I'm sure many people could use it to build their own generator.

[@InssiAjaton]

Congratulations - you did everything with a good safety margin in mind. The capacitor ripple rating appears most of time be specified at 10 kHz. In this case, we are probably dealing with something below 1 kHz. But what I have seen, the frequency effect to the ripple rating is something on the order of 5 to 10% one way or other. The built in rectifier diodes used to promise quite low voltage, but I believe present manufacturing does not justify those UNDER - ratings any more. I would think the present diodes are probably capable of 200 to 400 V or even more without any price penalty. I recall once, eons ago checking one ordinary axial lead 1 A diode rated 100 V and found it took 700 V, which then was the limit of my test gear. However, a smart choice using the external bridge. Good job!

[@DavidPozEnergy]

Thank you.

[@rivimey]

I'd really love to see an oscilloscope trace of the gen output with & without the cap in place, just for my education! I can believe it's fine as-is. One thought to bear in mind: if you want to clean a power line better, use several caps, with 1 or 2 orders of mag difference in value, in parallel: It might sound crazy to put e.g 2uF in parallel with 1000uF but the smaller cap will do better with high frequency ripple while the larger cap will mostly ignore HF and do low frequency. You can of course use 3 in parallel -- e.g. 1000uF / 50uF / 0.5uF -- to do an even better job, but that will not be needed here.

[@HirschCustoms]

So I did the same thing with one difference. I used a single cylinder diesel motor that runs on used motor oil. Essentially costing me 1 gallon of gas to provide me with 5 gallons of fuel. This is after 2 weeks of settling and passing the oil through 2 filters before adding it to the tank and adding a inline filter to that as well. This made my fuel for power cost almost nothing as I am a mechanic as well as can pick up oil from any shop in town for free

[@STRUTZKOFF]

hello, you can simplyfy the whole setup by simply connecting the altenator output to the lithium battery and then play with the rotor voltage to get sustainable output current to heat dissipation of the altenator

[@chrisfoote9413]

Just a thought, am I right in saying that if you turn off by switching the input to the victron charge controller off you may well give your bridge rectifiers a hard time with an instantaneous surge. I think it would be better to switch off the buck converter to the field coil as the first switch-off action.😊

[@carlitomadrona6211]

I did that system to charge 12v batteries during power outage during typhoon, those alternators are a little harder to drive while at work, I found out some videos on the net that those brusless hub motors from ebikes are super efficient and low rpm, you can have 48v output at a very low rpm, run through 3phase rectifier and connect it to charge controller the way you do it with solar panels.

[@olafschermann1592]

You could additional reduce vibrations by mounting a concrete plate to the plywood.

[@WJCTechyman]

Awesome job overall. I think the reason your Honda had more efficiency is it was engineered as a unit. If you have ever seen one in pieces the three phase alternator is directly coupled to the engine on the flywheel side as well as the proprietary components. At first I thought you had an EU7000is and thought it was fuel injected. Your project uses off the shelf components and probably cost far less than the generator did as the EU7000is is close to CA$6000 brand new before taxes.

[@BlàckÐèàth]

Very interesting to watch!! Now I wonder where is the point of diminishing return? Larger alternator, multiple alternators, beltless / direct drive.

[@ar-mory]

Great content, awesome work. Fuel efficiency at 30A load, 20A load? To maintain a 2.1-2.2 kw output and increase fuel efficiency, increase rotor voltage, for testing use adjustable constant current constant voltage supply. Should increase stator voltage decrease current, run cooler and lower engine rpm. Small increments in tenths of a volt. You may actually get close to the 5.8 kwh of the generator.

[@amaanqureshi1286]

Please optimize this set up even more!

[@patp7873]

Hi there First of all, I love your work 👍👍👍 One comment about your calculation or kWh/gallon (21:50'') I believe your home made generator is ways more efficient than you tried : Remember your engine generates around 5kwh And with even 3kwh you were ways of stalling. If you feel you have the time, a bigger alternator or a 2sd one in parallel could bring you above 3kwh ( at least 30% more efficiency per gallon which would bring you to 5.5kwh/gallon if not more) Let me know about your thoughts, and sorry for my English : I am french 😋

[@DavidPozEnergy]

Thank you for your comment. In video part 3, I fine-tune the kWh/gallon. kzbin.info/www/bejne/r4K3dImvrcmUq9Esi=4Bhb1ST07TtVpWte

[@premnathsamjahwan6616]

Hi David, what about increasing the rotor voltage from 12v to 16v? Great video, by the way.

[@LubomirValek]

Hi David. Nice experimets. I have new suggestions about the fuel efficiency. First engine is 7,5HP (5,595kW) and your alternator produces at peek 2,2kW. This way a lot of fuel is wasted on engine running at half power. Your test with honda generator and dedicated battery charger (with 100A charger current), as I remeber the values, was not run at same conditions so the result could not be compares. So to run engine at full power, adding second alternator will increase total output and could improve fuel effiecency. Second putting bridge rectifies in series could help Victron MPPT charge controller find better point. Maybe alternator current will not drop, but higher voltage will decrease all losses in wires and electronics. Good job.

[@atmphil1]

Put a bigger pully on the engine it will spin the alternator faster but spin the engine at a slower rpm saving gas and keeping the engine temps down.

[@SkyNoris]

Really cool setup David! I enjoy watching these projects and the results develop! Props again for all the hard work involved! I was thinking maybe this same setup could be used to harness wind or hydro energy.

[@leonhart2452]

A lot of small engines can be set up with a 12 volt output to charge a 12 volt battery as used in garden tractors, ride on lawn mowers or mini bikes to run lights. This 12 volt power could be used to power the rotor in the alternator.

[@joshnabours9102]

Stock alternators are about 40-50% efficient on average due to their 12 volt rectifiers. It will be interesting to see how external 48v rectifiers change that.

[@joey_f4ke238]

The fact that they don't use regular magnets and instead electromagnets also makes them take a blow to their efficiency

[@kellyj1464]

Have you considered testing the affect of raising or lowering the stator voltage? I know you're already gauging 40A as the max safe output by temperature, but it would be interesting to see if 15v for example could provide 40A at a lower RPM. Given the fan would be spinning more slowly, it would get hotter even if the same amount of heat is created. Since the heat created is based on current, I was thinking increasing the voltage may allow it run more efficiently, with the same amount of power delivered in higher voltage and lower current. Alternatively (pun intended), lowering the stator voltage may allow you to run the engine at higher RPM for the same current output and allow the motor to operate at a more efficient part of its power curve.

[@c.cmanakabubba9708]

I worked on older cars and trucks from the 1990s and earlier, years ago. As far as your temperature, it gets hot as hell under a vehicles hood. 160 degrees for performance and 185 and up for efficiency on old Chevy 350. These new engines run at 210 to be happy. I know your referencing the rectifier temperature, just some side information on closed environmental variables. I love learning curves also, It is that thirst for Knowledge that drives us, Stay Toasty David.

[@DavidPozEnergy]

Thanks for sharing.

[@vroor32]

Please explain more about that temp curve from performance to efficiency. I have a 1999 semi truck with a 12.7L Detroit and noticed it runs at 160⁰ but idles at 200⁰

[@lancealderman2755]

I'd like to follow this conversation more than anything... With the 12.7 if it was a normal vehicle I'd say thermostat should be holding you at optimal temperature. Other time idle is higher than running is when radiator is a little clogged and doesn't flow as well at idle. But I'm not familiar with diesels either so...

[@benhoffman7672]

Keep in mind that David's alternator measurement was ~100ºC not ºF

[@MichaelAppleman]

Very cool. I'd love to see some tinkering and see how things it affects the efficiency. Larger or smaller alternator? Maybe some alternators have a different design? Gearing for higher or lower rpm?

[@casemodder89]

lager alternator = thicker wires = less heat = higher efficiency. and 3000 Alt RPM is the sweetspot. alternators can take up to 18K rpm on some models. but energy loss on the fans rises squared with rpm. so low rpm is low amp output and high rpm is a bit higher amp output but at way worse efficiency.

[@Cabinlab]

Was wondering the same thing about messing with gearing to figure out the peak efficiency

[@ronstarner1103]

If I remember correctly you can control the charging with exciter ( your buck converter) and also can you figure out a way to link top of alternator to motor block with turnbuckle.

[@offgridwanabe]

Nice work at least for me in the winter 100 hours of running which would produce about 250kwh would only last maybe a week even with the reduced solar input so I am keeping my grid for now with the net metering and I can store all I can make in the summer (big battery) lol. Great video you are a good teacher.

[@rivimey]

Of course you could always look at ways to reduce your power demands... over 250KWh/week is a massive amount for one household.

[@BensWorkshop]

That is quite interesting. The total heat output potential of 1 US gallon (As opposed to an Imperial gallon) of "gas" is 35.96 KwH. That makes this setup 11.68% efficient.

[@allornothing7957]

Would you share the maths behind this please? I'm running an inverter generator to charge 48v lifepo4, and wondering if a 48v alternator on my diesel engine will be more cost effective.....

[@thelwq]

If you have long cable run between alternator and regulator, you can place the bridge rectifier beside the regulator and use a couple of transformers to transfer power better. But be sure to use RCB and proper, double insulated cables. 😊