WHAT IS A GOOD GENERATOR ??

[Typhoon]

Originally Posted by newhaul

What about using a reduction gear drive? Increase alternator rpm and reduce engine rpm. Would it also absorb the side loading on the main shaft bearings? They can be had in almost infinite ratios.

Yes , that is actually in my mind for the next build, if I ever get a bigger boat .

20 horse Yanmar generator engine with a gear drive on the crankshaft driving two Eco-Tech alternators at 6000 RPM into two separate LifePo4 battery banks .

Hot, they would pump 275 amps, times two , or 550 amp hrs in one hour of running .

Energy problems on a sailboat would be a thing of the past . Actually I have enough power now for just about everything on board, and then some.

Regards John.

[newhaul]

On my 29 in looking at putting a 200 amp small frame one wire alternator out of a cop car on the volvo.
(It is already setup for small frame gm type alternator.)

[john61ct]

With the small-frame alts overheating is the main issue, and many regulators just drop voltage, thus amps output through the floor.

Active outside air ventilation and a good VR like MC-614, temps sensing, small engine mode and "belt manager feature" helps keep thing under control, reduced output better than none when things get hot.

[newhaul]

Originally Posted by john61ct

With the small-frame alts overheating is the main issue, and many regulators just drop voltage, thus amps output through the floor.

Active outside air ventilation and a good VR like MC-614, temps sensing, small engine mode and "belt manager feature" helps keep thing under control, reduced output better than none when things get hot.

understood and this alternator would only be used when 400+ ah bank is at or just below 50% . My estimated power usage after I install refrigeration to be around 40 ah a day.
So would only need engine alternator for charging in the event of multiple days with no sun or wind.
( thinking ahead to eventual lifepo4 conversion).
Engine is currently in my girlfriends yard getting a deep cleaning and paint job before install.
( good time to do alt. Mount upgrades as needs)

[john61ct]

Originally Posted by newhaul

understood and this alternator would only be used when 400+ ah bank is at or just below 50% . My estimated power usage after I install refrigeration to be around 40 ah a day.
So would only need engine alternator for charging in the event of multiple days with no sun or wind.
( thinking ahead to eventual lifepo4 conversion).
Engine is currently in my girlfriends yard getting a deep cleaning and paint job before install.
( good time to do alt. Mount upgrades as needs)

Better usage is alt run in the AM for big amps acceptance, then renewables for the lower amp long tail, try to get to 100% every cycle.

If this is when SoC is only down to 70% easier on the alt as well.

Makes no sense to burn fuel once past 85%, batts acceptance way too low.

And yes LFP makes all such shenanigans just go away.

[newhaul]

Originally Posted by john61ct

Better usage is alt run in the AM for big amps acceptance, then renewables for the lower amp long tail, try to get to 100% every cycle.

If this is when SoC is only down to 70% easier on the alt as well.

Makes no sense to burn fuel once past 85%, batts acceptance way too low.

And yes LFP makes all such shenanigans just go away.

renewables will do it most of the time except in the dead of winter when I have several days of rain and little wind. 400 watts solar and 400 watts wind. Solar was giving me 3 ah in the overcast and intermittent rain yesterday. Refrigerator not in yet. Covers all of my power needs in under 2 hours Charging. ( in marina and all led lighting.)
so I'm hoping the alternator will solve my winter power issues.

[Q Xopa]

Hi All,

just a couple of comments about running our generators, or for that matter our main motors at low or lowish RPMs.

I know a lot of people like to do this to say go the furthest on the least amount of fuel, which makes perfect sense. Or to keep them quiet to not wake up the anchorage etc.

Running gas or particularly diesel engines like this for 'extended' periods will cause longer term engine health/ life issues.

Basically the cylinder pressure is lower so the piston rings aren't forced out onto the cylinder bore walls hard enough so they will/ may glaze. This reduces how effectively they seal and the efficiency. Without a strip down and hone this is pretty much irreversible. Caterpillar have a genuine part number packet of sand to pour into their engines to reduces this. I would suggest it is better to not get to this point in the first place.

Carbon will also form more in the engine from incomplete combustion as the temps and pressures are lower so carbon will burned or blow off less. This also will long term impede the airflow through the engine reducing performance.

So it makes sense to mostly run our engines at typically 2/3 - 3/4 speed range, which is best torque, or cruise range. For a 4JH4 TE I think its 1800-2000 (3200 is max). However for the reasons above the Operators manual recommend 6 excursions to max RPM for 3 minutes every hour. (off the top of my head, dont quote my figures or wording, but that the general idea.

It would be worse at a 'fast idle' speed at 1000 -1200 RPM. This is not to suggest this shouldn't be done, just that we are aware and allow for this.

That being said, of course we shouldn't run our motors at max RPM for extended periods either as this will definitely increase wear and shorten their lives. Not to mention blow our fuel bill and annoy everyone with the noise.

Also getting back to fuel efficiency. I read a paper recently penned by, I think, a mid West ag college, about fuel efficiency in tractors. Without searching for digging this report up again so not talking exact numbers, but the gist was that the tractors typically burn in the order of twice the fuel at idle to do the same amount of work they would at 2/3- 3/4 throttle. I knew from my apprenticeship days that idle was less efficient but I didn't realize the extent was to that degree.

Again no big deal, not saying we shouldn't do this for our own reasons, just pointing out what the implications are and how to mitigate them.

Diesels, and even gas motors are fickle critters. But if we understand and maximize their strong points they can serve us very well.

Did I mention that Diesel is 15-40% more efficient, and longer lasting than gas motors.

This is, IMNSHO, is where a DC Diesel gen has it all over a AC gen. AC gens cant vary their RPM so we cant vary the noise, fuel consumption, wear etc to serve our purpose to anywhere near the same extent we can with a DC gen.

Just saying (or maybe picking an argument).

[missourisailor]

Originally Posted by Q Xopa

Hi All,

just a couple of comments about running our generators, or for that matter our main motors at low or lowish RPMs.

I know a lot of people like to do this to say go the furthest on the least amount of fuel, which makes perfect sense. Or to keep them quiet to not wake up the anchorage etc.

Running gas or particularly diesel engines like this for 'extended' periods will cause longer term engine health/ life issues.

Basically the cylinder pressure is lower so the piston rings aren't forced out onto the cylinder bore walls hard enough so they will/ may glaze. This reduces how effectively they seal and the efficiency. Without a strip down and hone this is pretty much irreversible. Caterpillar have a genuine part number packet of sand to pour into their engines to reduces this. I would suggest it is better to not get to this point in the first place.

Carbon will also form more in the engine from incomplete combustion as the temps and pressures are lower so carbon will burned or blow off less. This also will long term impede the airflow through the engine reducing performance.

So it makes sense to mostly run our engines at typically 2/3 - 3/4 speed range, which is best torque, or cruise range. For a 4JH4 TE I think its 1800-2000 (3200 is max). However for the reasons above the Operators manual recommend 6 excursions to max RPM for 3 minutes every hour. (off the top of my head, dont quote my figures or wording, but that the general idea.

It would be worse at a 'fast idle' speed at 1000 -1200 RPM. This is not to suggest this shouldn't be done, just that we are aware and allow for this.

That being said, of course we shouldn't run our motors at max RPM for extended periods either as this will definitely increase wear and shorten their lives. Not to mention blow our fuel bill and annoy everyone with the noise.

Also getting back to fuel efficiency. I read a paper recently penned by, I think, a mid West ag college, about fuel efficiency in tractors. Without searching for digging this report up again so not talking exact numbers, but the gist was that the tractors typically burn in the order of twice the fuel at idle to do the same amount of work they would at 2/3- 3/4 throttle. I knew from my apprenticeship days that idle was less efficient but I didn't realize the extent was to that degree.

Again no big deal, not saying we shouldn't do this for our own reasons, just pointing out what the implications are and how to mitigate them.

Diesels, and even gas motors are fickle critters. But if we understand and maximize their strong points they can serve us very well.

Did I mention that Diesel is 15-40% more efficient, and longer lasting than gas motors.

This is, IMNSHO, is where a DC Diesel gen has it all over a AC gen. AC gens cant vary their RPM so we cant vary the noise, fuel consumption, wear etc to serve our purpose to anywhere near the same extent we can with a DC gen.

Just saying (or maybe picking an argument).

"Q".
Excellent post and spot on...But a few adjustments.

First off, gas engines should NEVER be ran at idle (or just above idle) for extended periods of time. With out higher RPM's the crank cant throw enough oil on the cly walls to keep them lubed.
Diesels can run all day long at idle, because of the paraffin that is added to the fuel.

Second, Diesels should not be ran at low (idle) RPM when LOADED due to glazing as "Q" stated.

But there are thousands and thousands of diesels out there that are rarely shut down. And when not loaded, are kept at "warm" speed which is usually just below idle.

Just to cement "Q"'s point about fuel efficiency RPM band, here is a link to a 1 cly diesel engine, that is used in a very popular marine gen set (there is even a picture of it on this thread).
http://engine.kubota.co.jp/common/pdf/ea330_e4.pdf

The graph on this *.pdf shows the engine is most efficient between 2200 and 2400 RPM. And least efficient at the ends of the RPM range.

[john61ct]

> Covers all of my power needs in under 2 hours Charging

Only if LFP, or just topping up from very high SoC.

With lead, from 80% to true 100% can take 4-5 hours even with a 300A charge source.

> so I'm hoping the alternator will solve my winter power issues.

can do, if run *before* solar day starts

[newhaul]

Originally Posted by john61ct

> Covers all of my power needs in under 2 hours Charging

Only if LFP, or just topping up from very high SoC.

With lead, from 80% to true 100% can take 4-5 hours even with a 300A charge source.

> so I'm hoping the alternator will solve my winter power issues.

can do, if run *before* solar day starts

I guess I should have stated specifics I am all led and overnight now I just use about 2ah for lights. So usually right now sans refrigeration I am keeping my bank (400ah) essentially fully charged.

[john61ct]

At that rate, 2 hours a week might do it. 8-)

[Lambretta]

What a great thread ........ I have found this REALLY informative as I have recently signed for a new build on a 50ft cat (not a production cat - ) and am seriously looking at the power set up at present (build starts next year) so am going for a 24v set up on the boat and (probably) electric motors (which will be 48v)

So a BIG thanks to
Pilot 64
John 61
Dockhead
ColdEh Marine
and others for your time and effort in building and contributing to this thread is much appreciate by me and I am sure by many others seeing that over 6000 people have looked at it

It really has crystalized a lot of my thinking and I have learnt a huge amount and for that I am most grateful

[warrior 90]

Q Xopa That is the other side of the coin

Carbon will also form more in the engine from incomplete combustion as the temps and pressures are lower so carbon will burned or blow off less. This also will long term impede the airflow through the engine reducing performance.

So it makes sense to mostly run our engines at typically 2/3 - 3/4 speed range, which is best torque, or cruise range. For a 4JH4 TE I think its 1800-2000 (3200 is max). However for the reasons above the Operators manual recommend 6 excursions to max RPM for 3 minutes every hour. (off the top of my head, dont quote my figures or wording, but that the general idea.

My conclusion:
Searching for the best efficiency rate (Torque+RPM+Fuel) and gearing a High Output DC alternator to max out amps in a giant LFP UPS for fast bulk charge to maintain LFP between 40 - 80% state of charge. To top off to 100% using all the other DC sources.
But this only works with LFP. LA batteries will not be able to absorb that fast.
The high absorbtion rate of LFP will keep the run time of the gen low.

A further idea for the carbon built up. Yeah, sounds a little exotic. Hope, now You guys don´t think I am nuts
A small H2O generator injecting gas in the air inlet will reduce the built up of carbon and reduce emission. The H2O gas will speed up the flame velocity of the combustion and their fore burn off the carbon built up. I have confirmed this fact on a Jeep Wrangler 6cyl 4L engine. I did serious test on a gas analyser and the results showed almost "CERO" emission and driving showed a better fuel efficiency of 10-15%. Those were the results on this particular engine. However I have not made any tests on Diesel engines. To stay on the conservative side and forget all the mambo jambo. During my tests I observed the spark plugs and they were totally clean... No signs of carbon built up.... simply a sign of better combustion.
Of course some might argue H2O is a dangerous gas. I would say; all forms of energy are dangerous if not handled properly.
I took care of the safety issue by a relay with a timer using the signal of the oil pressure. Of course the H2O gen also uses amps but if used only for preventing carbon built up a small amount of gas (5 - 10amps) is sufficient and the amp draw will be insignificant and also be offset by increased combustion (fuel consumption)

[john61ct]

For my use case, prefer lower rpms for the noise issue.

Thinking, adjust pulley ratio specs so occasionally rev'ing up to the speed optimal for clearing the carbon, doesn't spin the alt **too** fast.

Does that higher rpm do its job even if the load is greatly reduced?

IOW 95% of running time full load at low rpm, then 5% of the time spin the motor faster for longevity, but zero out field current so the alt isn't a load anymore.

[newhaul]

Originally Posted by john61ct

For my use case, prefer lower rpms for the noise issue.

Thinking, adjust pulley ratio specs so occasionally rev'ing up to the speed optimal for clearing the carbon, doesn't spin the alt **too** fast.

Does that higher rpm do its job even if the load is greatly reduced?

IOW 95% of running time full load at low rpm, then 5% of the time spin the motor faster for longevity, but zero out field current so the alt isn't a load anymore.

that 5%run time without load on alternator seems like a good time for a 700 watt 12v water heater element. If just to add some load when needed. ( would provide approx 50 amp load ).heck at that you could run 2 of them for a good load.