DC Generator - Yanmar 1GM10

[iain_scott]

Hi All,

I'm looking for a high output DC Generator. I've noticed there are only a few off-the-shelf solutions. The Ample power Genie 150A unit being one of them. This seems really quite expensive though. For what is basically a diesel engine with a large alternator I would rather build my own.

I'm thinking of buying a Yanmar 1GM10 bobtail (no gearbox) and mounting a balmar 90 series 150A dual 1/2" belt alternator to where the exisiting yanmar 35A alternator is.

I've looked at the graphs and I reckon I need to run the engine at around 2000rpm which will give 5hp.

I think a ratio of 2.5 (2.7" / 7") for the pulleys will be optimum.
For 2000rpm I'll get 5030rpm at the alternator. According to the balmar output graph it can supply up to 145A at that rpm.

Using the rule of thumb of 1hp for every 25A, I could get 125A max at this rpm. I have 4 T105 6V batts giving a total of 450AH capacity. With a Sterling PDAR regulating the alternator I shouldn't expect the batts to need more than 100A. If it does, I can always turn up the rpm of the engine.

I can see only a few small issues to overcome with this system.

1. Actually getting a large case alternator to mount to the existing mounting position of the 1GM10. Am I right in saying the yanmar has a dual foot 3.15" ID Mount? If so, would the Balmar 90 series 150A model fit OK?

2. Attaching a second pulley on to the crank (for the second belt).
Should I be able to bolt this to the existing yanmar pulley on the crank?
Does anyone know the diameter of the 1GM10 pulley? The tech docs don't specify this.

3. There is the side load issue for the engine bearings. Has anyone had any realworld problems with this? I could design a support bearing to take the load, but this seems overkill at the moment.

The other option is to direct drive it from the back of the engine, but I've not found any alternators which will give enough amps at such a low rpm. For noise/fuel economy purposes I'd rather run the engine at as low an rpm as I can get away with.

I'm also thinking of fitting a water separator on the exhaust so there is no annoying splashing noise.

I've searched extensively on the web but have only found one example of this being done with a 1GM10 - That was Ellen McArthurs round-the-world boat!

I have considered using a Kubota Z482 based engine such as the nanni or beta. But they are much more expensive than the yanmar (My yanmar dealer has offered me a good price on a 1GM10). However with the 2cyl vs. the 1cyl, it probably would be a little smoother going for the kubota.

Was wondering if anyone has thoughts/ideas/experience with something similar?

[bill good]

The 1GM10 was used as an alternator with the the speed fixed to give the correct AC frequency. The one I got was 240V 50hz @ 3KV. If you look around you might find one.

Regards Bill

[iain_scott]

Hi Bill,

Sounds interesting. Is the AC generator belt-mounted in place of the DC alternator? If so, is it a double belt 1/2" grove style? I'm just really interested in fitting a DC alternator, but the mechanics of attaching your AC alternator (assuming yours is belt driven) will probably be exactly what I'm looking to achieve.

What speed do you run the engine at?

How loud do you find it?

I noticed you're in Brizzy, by coincidence I'm living here now too!

[bill good]

No it was a direct drive off the crankshaft instead of the gearbox & governed at constant RPM for the AC freq. No noise proofing & that is how come I got it! I am now using it as one of my drive motors in my cat.There must be quite a few around here somewhere as I believe they were used in the fishing boats for primary 240 AC.

you can email me william.goodward@bigpond.com if you want further info. The alternator may still be available off this unit
regards Bill

[noelex 77]

This is what has been done on my boat, only with a 2cl 15 hp Nanni.
Works well. It is easy and cheap to fix, but is noiser than the comercial alternative.
Let me know if you want pics or details.

[iain_scott]

Originally Posted by noelex 77

This is what has been done on my boat, only with a 2cl 15 hp Nanni.
Works well. It is easy and cheap to fix, but is noiser than the comercial alternative.
Let me know if you want pics or details.

Hi,

Thanks for getting in touch. I'd be really interested to see some pics of the install if possible. I'm sure the pics might answer a few of my questions, but here goes anyway! :

What type of alternator do you use?

Do you use a dual-belt system? If so, was it easy to fit a second pulley to the crank?

Where abouts is the Nanni situated? If it's in the engine room, do you have any further sound insulation shield round the engine?

I'll be mounting the genny above my Yanmar 4JH in the engine room. It's a centre cockpit boat with the engine room underneath the cockpit, so plenty of room. I'm thinking of building a separate soundproofed enclosure (with adaquate ducted/forced air) round the 1GM10.

What rpm do you run the engine at?

Thanks again for your help with this. It's great to see someone else has a similar system that works well.

[Cheechako]

I have built 3 DC units based on Kubota engines. Two were based on the little "arrow" 1 cyl engine. One was based on the 2 cyl kubota. The 2 cyl seemed to have some real harmonic vibration problems, not sure if that was the engine or something I did in making the frame. I had a watermaker and a 125 amp alternator powered from the output shaft of the enigine. I had a custom pulley machined and really short belts. Bolts kept coming loose on the engine (factory engine bolts) and eventually the pulley split off one sheave due to vibration. The smaller one cylinder units were successful though. The advantage of these units is they are low rpm and quiet. You still need to have a pulley machined that drives a water pump">raw water pump as well as the alternator. Your battery bank doesnt appear too big, you might consider just going with a 100 amp alternator and single belt. You can only put high amps in for a short period of time anyway, then your batteries quit accepting the charge rate (heat up). How do you intend to cool the engine exhaust? or will you run an above deck hot exhaust? Heat exchangers/cooling is usually the hardest part. The beauty of the little horizontal cyl Kubota is it has a cast iron foot the alternator bolts right on to. Could you go with a low rpm Alternator and direct drive? That would be a great setup, even if the out put isnt as high, as I said, once the batt's heat up you cant charge fast anyway.....

[noelex 77]

Originally Posted by iain_scott

Hi,

Thanks for getting in touch. I'd be really interested to see some pics of the install if possible. I'm sure the pics might answer a few of my questions, but here goes anyway! :

What type of alternator do you use?

Its a 12v 130 American Persolite? and the original 65? amp unit on the front of the engine.

Do you use a dual-belt system? If so, was it easy to fit a second pulley to the crank?
There is a separate shaft with 2 bearings. A duel pulley leads to the 130A alternator. There was a second take off that ran a watermaker compressor, but I have removed this.


Where abouts is the Nanni situated? If it's in the engine room, do you have any further sound insulation shield round the engine?
Exactly as you describe below. It even sits above a Yanmar 4JH.
The whole engine bay is insulated with foam.

I'll be mounting the genny above my Yanmar 4JH in the engine room. It's a centre cockpit boat with the engine room underneath the cockpit, so plenty of room. I'm thinking of building a separate soundproofed enclosure (with adaquate ducted/forced air) round the 1GM10.

What rpm do you run the engine at?
Normally about 2100. It just sounds sweetest at this RPM

Thanks again for your help with this. It's great to see someone else has a similar system that works well.

Cheers John

[noelex 77]

Here is a photo I have just taken.

[Sterling]

this is an interesting thread... for a long time i've wondered why the need for an AC genset on a sailboat. the vast majority of the required power is DC - its so infrequent you'd need more than 2kw of AC if you can run Air Con, watermaker, refrigeration, etc from DC power / house batteries.

anyhow - this gave me an idea. why not the 9hp Yanmar engine plus the required accessory belts to power 1) large alternator 2) scuba compressor 3) watermaker 4) mechanical refrigeration? a clutch or simple transmission would be used to direct power to the correct accessory.

obviously they wouldn't all be run at the same time, but it would be a great way to make the most of the engine and space available.

[Cheechako]

Yes, a DC gen with watermaker pump is a great thing. DC gen's dont have to run at 3600 rpm to make correct voltage like AC gens so they can be much quieter. (I think one company makes an AC gen that works at 1800 rpm) Additionally, you could add a refrigerator compressor and really have the "bee knees". The little Kubota is super quiet at reasonable rpm and sips about 1/2 pint an hour. Mine occupied only about 2 ft x 1.5 ft x 1.5 ft. The trick is to run only the alternator at first while it is putting out 85-100 amps for 15 mins or so, when it steps down in output, then turn on the watermaker etc.... Compared with wind gens, solar panels etc all over your boat it is great. My four winds wind gen was noisier than my Kubota!

[Cheechako]

just use 12v electric clutches for the fridge and watermaker....

[Sterling]

Originally Posted by Cheechako

just use 12v electric clutches for the fridge and watermaker....

yep. seems like for the person interested in a project, this is the way to go. cheap power and loads of redundancy - after all, you can still have a 12V DC pump for the water maker and DC motor for the fridge. then if the small motor fails, you still have solar and the primary motor / alternator.

[Cheechako]

I think my biggest mistake was going with an aluminum frame on all 3 units I built. I would go with steel on another one. Steel absorbs vibration so much better as well as having a much higher modulus (less flexing), and doesnt crack from cycle fatigue. Blast it and paint it or have it powder coated! Ample Power makes the Genie with the same little engine (Pic)

[Cheechako]

Unfortunately this pic is the back side insttead of the pulley side, but that is the alternator on the far right.... http://www.amplepower.com/products/b...ual/index.html