Why a generator?

[socaldmax]

Originally Posted by Crazy Talk

Understood. I have no proposals yet, just an attempt at understanding. My current (Get it? Current?[emoji1] ) understanding of electric is weak so I've been doing quite a bit of reading to get up to speed.

I read a rather spirited thread about generating and storing electric, primarily around the use of a watermaker and how to charge batteries on cloudy days. The alternators seemed to have limiters for both time and heat which hurt charging ability. Their design isn't optimal for charging banks of batteries.

I like my Yamaha 2000w generator but adding another fuel on board doesn't thrill me.

And I can't ever see myself spending $5K+ for a diesel generator.

They all have drawbacks and I'm trying to figure out the drawbacks to the PTO. You already have the power source and the fuel. You'd get a lot more out of it than an alternator.

I'm just not seeing what the drawback is.

The only difference between a PTO generator and a belt driven alternator is the connection method - one uses a shaft, the other uses a belt.

The same current and heat limitations inherent in an alternator would also affect the generator. The advantage of a belt driven alternator is that you can vary the crank and alternator pulley sizes to obtain the optimum rpm for the alternator at the rpms that the diesel engine will be cruising at, as opposed to the (usually) fixed ratio of a PTO.

The advantage to a PTO on a tractor, for example, is the ability to easily change attachments for different needs or remove them for repair.


What you might find more suitable for marine use is a Kubota driven generator with the ability to be outfitted with an engine driven watermaker, dive tank air compressor, refrigeration compressor, etc, pretty much whatever you want. Each accessory is belt driven and clutch controlled, so if you need to charge tanks and batteries, you can do that, or cool the fridge and charge batteries, etc.

Aquamarine, Inc -

[Crazy Talk]

Originally Posted by brianlara 3

Crazy, re the generator not requiring similar as the prop.
On this proposed generator, could you imagine this generator pushing the boat into a 10knot wind at hull speed ?
[emoji2]

Good point. But it does take some mush to get those generators turning. What I didn't consider was the flywheel effect once it is moving. Probably need alot more oomph to get it to speed than to keep it there.

[Crazy Talk]

Originally Posted by socaldmax

The only difference between a PTO generator and a belt driven alternator is the connection method - one uses a shaft, the other uses a belt.

The same current and heat limitations inherent in an alternator would also affect the generator. The advantage of a belt driven alternator is that you can vary the crank and alternator pulley sizes to obtain the optimum rpm for the alternator at the rpms that the diesel engine will be cruising at, as opposed to the (usually) fixed ratio of a PTO.

The advantage to a PTO on a tractor, for example, is the ability to easily change attachments for different needs or remove them for repair.


What you might find more suitable for marine use is a Kubota driven generator with the ability to be outfitted with an engine driven watermaker, dive tank air compressor, refrigeration compressor, etc, pretty much whatever you want. Each accessory is belt driven and clutch controlled, so if you need to charge tanks and batteries, you can do that, or cool the fridge and charge batteries, etc.

Aquamarine, Inc -

I'm hoping to get by on my solar panels and battery bank as much as possible so I doubt I'll ever see a 5kw on my boat. But I do like the idea of the PTO off the generator.

[denverd0n]

Originally Posted by Saleen411

I've wondered about this on charter boats....."run the engine at least 2 hours a day to charge the batteries" policy.

I think that most charterers run the motor a lot anyway. At least, that has been my observation.

Myself, both with my own boats and when on charters, if I have not run the engine enough to charge the batteries then I do that when I am setting the anchor for the night. Put it into reverse and run the revs up to set the anchor. Then back it down to a high-idle speed and just let it run for a while. If the anchor (or mooring, if that's what you are using) cannot hold the boat steady for an hour or two of high-idle time in reverse then you do NOT want to spend the night there anyway!

[John Holbrook]

Crazy you raise an interesting question. With new battery technology allowing greater acceptance rates will it become possible to charge battery banks at say 10kw or more per hour? That would certainly load up most sailboat engines and make running a genset except for Aircon perhaps unnecessary.

With regards to loading and glazing no modern pleasure boat engine should be run at max speed, that will shorten the life, use more fuel and in the case of a sailboat probably give a tiny increase in speed.

Modern fuel injection system meter fuel a lot more efficiently at light loads and glazing isn't such a big issue as it used to be. Haven't no said that use runny no the engine with the standard alternator wild be too small a list. A new yanmar that makes 45hp at the crank at 3000rpm makes 15hp at 1200rpm. A large 200amp 24v alternator would draw about 7hp and if that alternator reach 200amps at 1200rpm the engine would be 50% loaded which maybe fine but it would be best to check with the manufacturer. The other issue is getting the engine to reach its correct operating temp.

[brianlara 3]

"Correct operating temperature" is the problem and low combustion chamber temps = incomplete fuel burning which imbeds carbonised fuel particles into the cross hatch of the bore = glazing = poor piston ring sealing and the problem becomes exponential with continued abuse.
Low level glazing can sometimes be burnt away with a good fanging, meaning, say, 8 hours @ hull speed (in the case of a boat).
The people I'm trying to protect are those with less than 'state of the art' engines who continue to abuse their motors/wallets by charging batteries whilst anchored.
Any yes, engaging reverse at 20% load whilst anchored would likely prevent glazing.
And if your pick wont hold with a piddling 20% load then why have it?
I am NOT espousing the use of reverse gear for frequent charging as gearboxes are designed to work hard when producing forward thrust more so than in reverse where thrust bearings will suffer premature failure.
Overhauled many motors which were not WORN out....their cylinders were glazed.
And not only diesels in boats either. WYNNS (friction modifier/extended warranty) products added to car engines prior to bieng "run in" have caused many almost new car engines to be rebuilt prior to the expiration of warranty. And in my experience no manufacturer in Australia has been forced to honour their statutory obligations because of "owner misuse".
Sorry 'bout the rant sort of.

[Cheechako]

Most generators require a very specific rpm to generate 120 volts. Most diesel engines are not easy to set at a very specific rpm as most are used for propulsion also.

[a64pilot]

Originally Posted by Cheechako

Most generators require a very specific rpm to generate 120 volts. Most diesel engines are not easy to set at a very specific rpm as most are used for propulsion also.

Yes but, you know there is always a but, right
How hard would it be to scale up the inverter/ generator?
I wouldn't be surprised if one of the majors, Yanmar or Volvo or someone didn't in the near future offer a prime mover that could also be a 5 KW or perhaps bigger generator. A way to handle the load of the generator without overloading the engine when using it as propulsion would be a two speed gearbox or a planetary gear system ala the Prius PSD

[John Holbrook]

Brian glazing is primarily caused by over fueling which leads to incomplete combustion (as you mentioned in your first post) which results in deposits that then work there way down the bores and form a varnish like layer. Newer fuel injection systems are much better at regulating fuel at light loads which reduces the threshold at which glazing can occur. During the break in cycle engines are particularly vulnerable to glazing as the pistons and bores have not yet bedded in.

Whilst the correct operating temp is important it is not the prime cause of glazing. I don't know what WYNNS is but it doesn't sound good. I had two Cat 3116s in my last boat and the additive in multigrade oil made it blow black smoke, Cat recommended 30w and that fixed the problem.

I'm not suggesting any runs their engine with a normal size alternator and agree with you that it will shorten the life of the engine.

[John Holbrook]

A64pilot like this?

http://www.powerequipment.com.au/wp-...-brochure1.pdf

I don't think Yanmar make it anymore.

[Cheechako]

Originally Posted by a64pilot

Yes but, you know there is always a but, right
How hard would it be to scale up the inverter/ generator?
I wouldn't be surprised if one of the majors, Yanmar or Volvo or someone didn't in the near future offer a prime mover that could also be a 5 KW or perhaps bigger generator. A way to handle the load of the generator without overloading the engine when using it as propulsion would be a two speed gearbox or a planetary gear system ala the Prius PSD

Yes, whatever you scale the speed to though, you are going to need to be able to stay at that speed, and repeatedly go back there when in Gen mode. I suppose maybe a diesel could be developed to have a governor that you had a set speed mode as well as a variable speed mode , with the flip of a switch?
Balmar made a variable speed generator for a short time . I forget what it was called... or how it worked.... evidently it didn't work out well...?

[a64pilot]

Originally Posted by John Holbrook

A64pilot like this?

http://www.powerequipment.com.au/wp-...-brochure1.pdf

I don't think Yanmar make it anymore.

Actually it seems to be simpler than what I had proposed.
Wonder why it didn't catch on?

[Crazy Talk]

Originally Posted by John Holbrook

Crazy you raise an interesting question. With new battery technology allowing greater acceptance rates will it become possible to charge battery banks at say 10kw or more per hour? That would certainly load up most sailboat engines and make running a genset except for Aircon perhaps unnecessary.

With regards to loading and glazing no modern pleasure boat engine should be run at max speed, that will shorten the life, use more fuel and in the case of a sailboat probably give a tiny increase in speed.

Modern fuel injection system meter fuel a lot more efficiently at light loads and glazing isn't such a big issue as it used to be. Haven't no said that use runny no the engine with the standard alternator wild be too small a list. A new yanmar that makes 45hp at the crank at 3000rpm makes 15hp at 1200rpm. A large 200amp 24v alternator would draw about 7hp and if that alternator reach 200amps at 1200rpm the engine would be 50% loaded which maybe fine but it would be best to check with the manufacturer. The other issue is getting the engine to reach its correct operating temp.

I was thinking why not scale the engine back and add an electric propulsion sytem instead. Someone on this board has one and i saw a pictuee pisyed sonewhere. The engine would be a generator for all the on board power hogs, batteries for daily consumption and batteries for propulsion. It achieves my original thought of one fuel for propulsion and power generation as needed.

[a64pilot]

Originally Posted by Cheechako

Yes, whatever you scale the speed to though, you are going to need to be able to stay at that speed, and repeatedly go back there when in Gen mode. I suppose maybe a diesel could be developed to have a governor that you had a set speed mode as well as a variable speed mode , with the flip of a switch?
Balmar made a variable speed generator for a short time . I forget what it was called... or how it worked.... evidently it didn't work out well...?

No you would not need a set speed as long as it was fast enough to supply power demanded, RPM could vary with load just like a little Honda does.

[Crazy Talk]

Originally Posted by a64pilot

Yes but, you know there is always a but, right
How hard would it be to scale up the inverter/ generator?
I wouldn't be surprised if one of the majors, Yanmar or Volvo or someone didn't in the near future offer a prime mover that could also be a 5 KW or perhaps bigger generator. A way to handle the load of the generator without overloading the engine when using it as propulsion would be a two speed gearbox or a planetary gear system ala the Prius PSD

After Brian burst my bubble, I was thinking along the same line, increase the workload to to make the diesel happy. I'm just the idea guy though.