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Hey folks, I've been kicking around the idea of building a belt driven generator. The more I look into generators the more I see they are not built for joe schmoe like me. They either are cheap Chinese generators that are constantly tearing themselves apart or HUGE industrial gensets. I don't need 20 kw or even 5 kw.
I think 2 kw sounds fine. Another issue is the lack of surge capacity. I want something that can power a 15 amp receptacle and start anything that will run on a 15 amp circuit. So i need a heavy flywheel. Those are things you just can't get on the market. So I am thinking of a car engine. I could buy a cheap lawn mower engine and run it slower and just buy a bigger one but a semi modern car engine could be had for the same price as a decent honda small engine. I got a decent idea on how to regulate it. Hoof governor or another home built design.

My question:
Would the gas consumption be better or worse?
I plan on running it at idle or a hair above and using pulleys or a gear box. Pulley would be better, i can redo the pulley if i want more power.

Thinking of using a geo metro engine. I read online idle consumption is .10 of a gallon of gas an hour. Only problem there is i can't figure out how much HP it would have. No AC or accessories so no extra power needed. I'd either remove the alternator or find the smallest one i can. Might use a small solar panel or charge it from my battery bank. I don't think a running engine requires a lot of power to keep it going.

The engine should have more inertia compared to a cheapo small engine so regulation should be smoother but could I add a flywheel weight to the shaft to smooth it out? I tried to figure the math on that but can't find anything on how big it needs to be. Technically it needs to store 1 watt of power roughly for an hour. In one second that would add a lot of surge capacity.

Anyone have experience in this?
 

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Anything with electronic ignition is going to take more power than you think, that is why even most large diesel generators are equipped with alternators to kee batteries charged during operation.
 

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You can build a genset like you are talking about... but the heads are not cheap and the cheap ones are Chinese made just like the generators... lol

Harbor freight sells a 7k belt driven generator head I was strongly considering.. I want to get one and mount it under the hood of my old '75 Mercedes 240d. Plenty of space... can run on waste oils, etc.. and I THINK it was around $250. Non chinese made heads of this size are over $1k

I'll see if I can find the link..

-EDIT-
299... plus a coupon would get it cheaper.

http://www.harborfreight.com/10000-watts-max-7200-watts-rated-belt-driven-generator-head-45416.html
 

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Others have had similar ideas to yours, but the problem is that you simply can't build a more reliable generator than those that are mass produced unless you are prepared to spend a lot more money, and you still might not achieve your desired outcome.

If all you need is 2 kW, then get a Honda or Yamaha inverter generator for about $1k. You'll never beat these for reliability, fuel economy, quality of power produced, sound levels, and longevity with anything you build yourself. Many people have run these for over 5,000 hours, and at least one guy has run his for 12,000. You'll be happy, but in the highly unlikely event that you aren't, you won't be happy with anything.
 

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///////////

Others have had similar ideas to yours, but the problem is that you simply can't build a more reliable generator than those that are mass produced unless you are prepared to spend a lot more money, and you still might not achieve your desired outcome.

If all you need is 2 kW, then get a Honda or Yamaha inverter generator for about $1k. You'll never beat these for reliability, fuel economy, quality of power produced, sound levels, and longevity with anything you build yourself. Many people have run these for over 5,000 hours, and at least one guy has run his for 12,000. You'll be happy, but in the highly unlikely event that you aren't, you won't be happy with anything.
I like this idea ^^^^^
 

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A Honda EU2000i is only a 1600 watt generator and often sells for $1000.

A 3500 watt (4000 watt surge) Champion is only $300. So, you can buy three with change left over, and have more power then the Honda.

Of - if some reason a person really wants an inverter-DC based generator - $450 buys a Harbor Freight Predator rated 2200 watts (2500 watts surge). So even with that - more power then the Honda, you can buy two, and still have change left from your $1000.
 

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For true 2000 watts the Yahama EF 2400IS is good--a bit more than the Honda, but gives the power.

I have used Honda generators for over 30 years--one I still own is 30 years old and still runs well.

As Clay suggests a Lister knock off with a good generator head is a bullet proof system.
I made a system with a 10 HP, 1200 RPM Yanmar diesel (used world wide for agricultural water pumps), belt driving a 5 KW head. At about 5,000 hours we re-wound the coils, and epoxy potted them. At 8,000 hours we did a valve job. Sold the running unit at over 10,000 hours.

What is proposed will be full of problems. The car motors will be way too complex. If you run them at idle they will not do well. You will most likely have ethanol related fuel problems
2 KW may not be enough for the surges. I would go at least 2.5 KW--may be 3, if you want 20 amps...(Which is often the case with some appliances)

Two choices--the quiet inverter 1600 to 2000 gas units, or a diesel....
 

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Harbor freight sells a 7k belt driven generator head I was strongly considering.. I want to get one and mount it under the hood of my old '75 Mercedes 240d.
How the heck would you hook it to the engine? 7000 watts with a belt drive likely needs at least four 1/2" vee-belts if it's not going to slip.

I got the same sort of problem on my 1978 Toyota mini-motorhome. I'd like to stick in a 150 amp (2100 watts) alternator but the engine only has a single 1/2" vee-belt drive and it's pretty hard to adapt more.
 

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Also, If you have a Cummins dealer near you, keep your eyes on them from time to time. The local one to me got a trailer load of factory rebuilt Onan generators and was selling them dirt cheap. I bought a 2k continuous Onan gas powered unit for $225 and it looked like new.

Glad I did to as the winter after, we had one of the worst winter storms in years... knocked out power to some for weeks and closed major highways for days on end. This little generator kept my fridge running, my tv, and a couple lights. Cooked on top of the wood stove... was a good time actually. 3 days on the generator running non stop and I don't think it used much more then 5 gallons of fuel.
 

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Discussion Starter #13
Okay thats a ton of replies, didn't expect that.

The cheap chinese generators I am referring to are box store specials. Harbor freight, briggs and scrap iron generic generators etc. The kind that blow up after 500 hours or 100 hours. I like champion because its a licensed clone of honda and they actually tend to last a really good long while and cost half as much or less than a honda. I've seen some of the smaller units go over 5000 hours and they cost less than 200 dollars.

I don't really much care for the inverter generators because i dont care for inverters. They can easily be damaged, especially with power tools and motors in general. Especially a pure sine unit. Lets say you cut some wood and the blade locks, it can spike the amperage so fast it fries the unit before the protection circuits can do anything.

Honestly while a honda is nice, I do think I can make a better unit. Might not be better quality power because I might use a cheap gen head but a lot of automotive engines are far superior to a small engine on portable generators. Hell an inline v6 ford 300 is known to go over 700k miles without a rebuild. The problem I run into is the low rpm units I want are huge and expensive. I can get a car engine for a lot less than a honda and even a champion (depending on size.) Complexity varies but the older models are a lot simpler. Also the larger oil capacity, more common parts and after market options make the car engine more appealing.

I want to keep it gasoline because i know gas engines better and i want to eventually run it on wood gas.
 

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Discussion Starter #14 (Edited)
Also, If you have a Cummins dealer near you, keep your eyes on them from time to time. The local one to me got a trailer load of factory rebuilt Onan generators and was selling them dirt cheap. I bought a 2k continuous Onan gas powered unit for $225 and it looked like new.

Glad I did to as the winter after, we had one of the worst winter storms in years... knocked out power to some for weeks and closed major highways for days on end. This little generator kept my fridge running, my tv, and a couple lights. Cooked on top of the wood stove... was a good time actually. 3 days on the generator running non stop and I don't think it used much more then 5 gallons of fuel.
I don't think i do, i see them from time to time on craigslist but they usually want 2000-3000 for one and i dont mean the new units. When its cheap its because its completely trashed and non working. Around here second hand is a joke, a ton of ******** that have no idea what they have but insist on top dollar and they will sit on it forever. The general rule of thumb is you have crap and they have gold. Its infuriating to deal with them. The economy is particularly bad her and power equipment is general is very expensive here, the few people who do deal in that are "mall spot" kind of businesses with high overhead and higher mark ups.

Is there a bottom end of rpm for an engine that doesn't help engine life or keep it cool and lubricated?

5 gallons for 3 days non stop you say? Now THATS fuel efficiency. 1800 rpm?
Just for reference where is this company who did this?
For something that cheap I would be willing to go for a drive...
 

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How the heck would you hook it to the engine? 7000 watts with a belt drive likely needs at least four 1/2" vee-belts if it's not going to slip.

I got the same sort of problem on my 1978 Toyota mini-motorhome. I'd like to stick in a 150 amp (2100 watts) alternator but the engine only has a single 1/2" vee-belt drive and it's pretty hard to adapt more.
According to those who've used the head, they run 2 belts on them without issue. As far as adding belts.. build a pulley. Pretty easy if the engine you are working on has a bolt on pulley or 2.. build a spacer.. go find another car in the junkyard with a bolt on v-belt pulley.. get longer bolts and bolt it on. Bolt on v-belt pulleys are easy to come by.. typically have a 4 bolt pattern but that's easy to change with a welder and a drill press or lathe.

I also considered multiple alternators and an inverter. Wouldn't be hard to do... but I've got the space for the generator head to mount on the inner fender (all steal) and have room for the additional crank pulleys.

For your toyota... look into a 3g alternator swap. Not sure how doable it is on that year.. but there are many people who have upgraded to later model higher output alternators over the years. Wouldn't need an extra alternator.. just a bigger one.
 

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For your toyota... look into a 3g alternator swap. Not sure how doable it is on that year.. but there are many people who have upgraded to later model higher output alternators over the years. Wouldn't need an extra alternator.. just a bigger one.
Some vehicles have lots of room for multiple-row crank-pulleys while others do not. Chevy K5 diesel Blazers have many added pulley grooves. Not much room on a 1978 Toyota truck. It came OEM with a 45 amp alternator and a 60 is about all the stock belt-drive can handle. It's about square-inches of contact with the belt. Stock alternator pulleys on autos are usually 2 3/4" or 3". They cannot be much bigger or the alternator does not spin fast enough at idle-speed to charge. So, a 2 3/4" pulley starts to slip when a load of 1000 watts plus is put onto it. The answer used to be dual pulleys like many ambulances had with the big Leece-Neville alternators. Then serpentine belts became common and they have more traction. Like on my 2002 Dodge Grand Caravan. It has a 160 amp alternator with a 2.1" pulley and 6 grooves for the belt.

If you wanted to turn a 7000 watt generator head - two pulleys would work but they'd have to be large diameter. If they were 2 3/4" like a stock alternator pulley, no way could two pulleys work.
 

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OP....sounds like you will be investing more money than you could go out and buy a good generator for...
Maybe you should shop around
 
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