DC Generator - Yanmar 1GM10

[goboatingnow]

Cheechako, I am just about to start a project building a DC generator using the Z series kubota engine ( cost about 1500 dollars inc marinization). I am considering a direct drive water cooled AC alternator which at 200rpm gives about 150 amps at 12V

I was intersted in your comments re the 2-clyinder, any further insights, I would have thought the Z series would be much smoother then the horizontal.

Also I have recieved feedback from people that have these commercially purchased 1-clyinder kubota units and they say they have to run very fast to get the amps and the whole thing is very very noisy

[Cheechako]

2 cyl: I built that one in about '98. Not sure if it is the same 2 cylinder or not... in line 2 cyl not V? I assume you mean 150 amps at 1200 rpm? I really dont know what the deal was with that engine, it felt smooth but seemed to have some high cycle vibration going on.... meaning ....not like the engine shook on the mounts, but vibrated. The custom 3 sheave pulley was keyed to the output shaft and appeared to run true. Eventually the last sheave on the pulley cracked and came apart!. The bolt holding the little Kubota alternator/magnetos kept coming loose etc. Maybe I just got an engine that was badly out of balance....? At any rate, I would use a steel frame personally.
1 cyl:The little horizontal engine (pictured above) was smooth for a 1 cyl engine and ... (Im not sure)... I dont think they are designed to run over about 2000 rpm.... unless they have changed them. I only ran mine in about the 1700 rpm range if I remember right and that for only 20 minutes or so,then I backed off to a nice 1200 rpm for the remainder of charging. I had a small water lift muffter and the thing was dead quit under my cockpit floor. People would come up to my boat in their dingy and we'd be talking and the'yd say "are you running your engine?" when they saw the water blurping out the exhaust port. The cheaper version (no flywheel!) is what I used. (this engine was originally designed for the freeway "arrow" signs) The more expensive one which I think is rated a little higher horsepower (8?) is what my buddy built his out of . He toured the South Pacific and has been back several years and I think is still using it... I used a 125 amp ample power small case alternator on mine with a soft start 4 step regulator. at about 90 amps output it wold load the engine pretty heavily for the first 15 mins or so. belts make some noise and a lot of black dust due to the extrem loads on them. Going direct drive is a great idea.
Someone makes a pre-marinized unit now? who? Beta?

[Cheechako]

me and my buddy used an aircraft vernier throttle adjustment that allows you to adjust for the sweet spot in the engine and lock it there. Simple, inexpensive device that can be mounted right on a bulkhead... no lever... The good one has a red button in the center, you push the button and it allows adjustment. Also, purchase the solenoid engine shut down option, much easier than using a cable set up.
A note to anyone using the 1 cyl engine: the fuel fitting on the engine must be left in the position it is when you receive it. It seems like an odd angle to attach your fuel hose to but gets an air bubble if changed to a more convenient angle!

[iain_scott]

Originally Posted by Cheechako

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.....

Hi Cheechako,

Although I just have a 450Ah bank to charge, I'd quite like to be able to run heavy loads on the inverter - possibly taking up to 150A DC.

The Yanmar 1GM10 is a raw water cooled engine so I think it should be as simple as bolting on the large alternator in place of the small 35A stock one. (as well as adding a second pulley to the crank)

I'm a little worried that when I have over 100A load for long periods of time I may cause early fatigue to the crank pulley bearing?

Anyone have thoughts on this?

Cheers, and thanks again for everyones input.
Iain

[iain_scott]

Originally Posted by 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.

I couldn't agree more with your comments about AC vs DC.
I told the yanmar dealer that I wanted a BIG output DC generator, but he kept trying to sell me an AC Mase generator. They run at 3000rpm, are very noisey, use a lot more fuel than a 1GM10 @ 2000rpm and would only give a fraction of the charging capacity through my AC battery charger.

For refrigeration, if I was to bolt a compressor on to the generator it would mean that I would have to run the generator at least once a day regardless of whether I was plugged in to AC shore power or not. On balance, I've decided to go the DC fridge/freezer option (just ordered a new waeco freezer/fridge 12V DC system). I suppose I could have both systems, but it's not too high up the priority list at the moment.

When we re-engined to the Yanmar 4JH we got rid of the engine driven compressor on the old Perkins. Now we will be able to leave the boat for a length of time with the food in the freezer/fridge not needing regular gen set time (if on shore power!) However, I guess the disadvantage of this is that the batteries will get a deeper discharge since the fridge is running off 12V. Hence longer gen set run time for a recharge when away from shore power.

We're going to fit a watermaker in the next year or so. I'm not convinced that running it off the DC genny is a good idea though. If the genny was to fail we would be without watermaking capabilty. However, if we got a 12V (of 230V off inverter) watermaker, we could run it when the main engine's on when underway too. And if both engines fail (e.g. bad batch of diesel) we can still run it off the battery charger powered by our petrol Kipor 1kW AC genny.

Because it will be a 12V watermaker, we'll probably not get the same GPH rate as an engine driven compressor system, but I think the redundancy is a good compromise.

Anyway, I've gone off my own topic!

For the Yanmar 1GM10, I would like it to have a stop solenoid rather than the mechanical lever stop. I've had a good look online but haven't found of anyone who's added this to the 1GM10. Anyone have any ideas?

I've also been thinking about the need to control the throttle. I was thinking of just adjusting the idle screw all the way up to ~2000rpm.
The little engine generates just under 5hp at this rpm. But if I was to draw the full 150A DC from the alternator I'm worried that the engine will become overloaded and start to produce black smoke. This lead me on to thinking about automatic throttle control, somehow reading the alternators field control wire and adjusting the throttle accordingly. This seems overly complicated though. Perhaps just a manual throlle lever which I can adjust as required might be in order.

The aircraft vernier throttle adjustment sounds exactly what I should get. I've not heard of this before. Do you know where I can get one?

Of the folk that have a similar setup, do you ever find your engine overloaded? What actually happens?

noelex77 - many thanks for taking the photo of your system. It looks very well engineered. It has given me food for thought as to whether I should do the same with a small shaft and two bearings from the back of the engine or just bolt on the alternator to the usual spot.

goboatingnow - I've also looked into the kubuta engines. Is yours the Z482? That is an amazing price for it fully marinized! Where is your source? I was quoted well over £3000 for a bobtail beta 14 (BZ482 based marinized) engine!! That's the price you pay for living in rip-off Britain!

I've looked into getting a Z482 and marinizing it myself. I think I would just need a block heat-exchanger, raw water and fresh water pump.
However, by the time I've spent all that money it would be more expensive than the 1GM10 which is ready to go with a full warranty. The only benifits I can see of the kubota route are hot water (since fresh water cooled) and smoother running (since 2 cyl). But that's quite a premium!!

Cheers All!

Iain

[Cheechako]

The raw water cooling on the little Yanmar makes things pretty simple anyway.. and if it only lasts 5 years... so what! Will you have a wet exhaust elbow and muffler? I'm not sure about the side load issue, Your belts should not be too tight, but there is a load there and the belts get worn pretty fast on a big alternator.... make sure it is easy to get to to tighten them. Gates Green stripe seem to be the best, but the dayco with the cooling notches I thought were good when I couldnt find a green stripe. 5hp may be a little marginal for 150 amps.... anyone else know?
Iain: You should be able to find the vernier on-line, I cant remember where I got mine.... been a few years. You want the one with the red button in the middle. Push the button and slide the cable in and out for gross adjustment, turn the knob for fine adjustment. They are pretty cool and are not that expensive.

[iain_scott]

Originally Posted by Cheechako

The raw water cooling on the little Yanmar makes things pretty simple anyway.. and if it only lasts 5 years... so what! Will you have a wet exhaust elbow and muffler?

Hopefully it'll last longer than that for the price of it!

Here's a pic of the engine showing the exhaust setup:

http://www.yanmarmarine.com/uploads/...full_right.jpg

For the exhaust I'm thinking of taking the rubber hose from the mixing elbow down to a waterlift muffler then up to a water/gas separator then take the cold gases to a thru hull a ft below deck level and take the raw warm water to a thru hull just on the water line.

I'm leaning towards the Vetus water/gas separator. I've noticed that mastervolt also sell them. Has anyone got experience with either one good or bad?

The addition of the water/gas separator will stop the splashing sound and hopefully quiet the system down even further.

Thanks for the advice on the vernier throttle. That's exactly what I'll get!

I still need to work out whether the Balmar 90 series alternator will actually fit and if I can bolt on a second pulley to the crank pulley....

[Cheechako]

I've never heard of the water gas separator, I imagine the diesel will be louder than the water exiting the hull anyway, so maybe just keep it simple...?