WHAT IS A GOOD GENERATOR ??

[john61ct]

> 200 amp small frame alternator is only 200 amps for a very short time, if not seriously derated trying to run them at high power burns them up.

No, all the DC genny discussion above is about LFP chemistry banks, which will accept full max output at given rpm from the alt.

And the problem you're talking about is caused by using small-frame (likely stock automotive type) alts, or overheating from insufficient ventilation.

All the alts discussed above can produce over 200AH all day long at low RPM. That's why they need high torque engines and robust serpentine belts if not direct coupling.

At 200AH per hour even a very large LFP bank can be fully replenished in a short time, which minimizes genny runtime if that's all it's being run for.

Even smaller alts designed for charging house banks like Balmar, Ample etc can output close to their rating for hours, long as ventilation is good.

[kenbo]

For those salivating over the Eco-Tech alternator...

https://www.ebay.com/itm/NIB-NEW-Eco...RYdZJb&vxp=mtr

[a64pilot]

I do not believe the Balmar AT series alternators can produce 200 amps continuously at any RPM.
I believe not many alternators can, and those that can are large and heavy things

[john61ct]

Yes they are heavy, and yes Balmar, which I did point out was smaller, does top out around 200. Leece Neville goes way higher, I think Delco 300A as well.

As stated above, very common for school buses, fire trucks, ambulances other emergency vehicles.

Also the market for very large capacity inverters, LVD battery protectors etc.

Can often be picked up on eBay very cheap.

Of course for redundacy and flexibility, some may prefer to run two smaller alts rather than one big one.

[a64pilot]

One good thing about DC power production, there is no paralleling issues like there is with AC generators, you can run multiple DC sources without a problem.

[newhaul]

Originally Posted by a64pilot

One good thing about DC power production, there is no paralleling issues like there is with AC generators, you can run multiple DC sources without a problem.

amen to that alternator, solar, and wind. They all work great together.

[Q Xopa]

This is all good stuff. I'm also a fan of the DC Diesel Gen concept.

A couple of extra comments if I may.

HP and Torque. Yes all correct, but to clarify a little-

Torque is a force, twisting force. Doing up a bolt for example. Even when the spanner or Torque wrench isnt moving any more, but hold 'pressure on doing the bolt up is still torque. So in this case there is still a 'force' but no 'rate'.

HP is the rate at which this force is being done. Ie the rate of work the average Scottish draft horse could do, ie lift a the power needed to move 33,000 pounds a distance of one foot in one minute. Minutes being the rate in this case.

How this actually looks on a dyno graphs is that the Torque curve peaks at lower RPM than the HP curve. The max Torque peak is the most fuel efficient RPM. So the RPM where where maximum force is generated for comparatively least amount of fuel burnt. Most people use this as their optimum cruise RPM. This is the design 'speed' for a given motor that the air/ fuel/ exhaust flows are working at their best to exert maximum pressure on the pistons.

Above this point you get less force out of the motor but because it's being done at a greater rate the HP increases for a little bit. Then the force is decreased to such a point because it cant breath fast enough, that even with the increasing rate 'HP' drops off too.

So if we can maximize our running at max Torque RPM it will be the most efficient. Ideally this is where we want our generator to be doing all it's hard work. And when it's not working just idling sipping fuel, not screaming unloaded like an AC Gen has to do to maintain it's frequency output.

So for my little 2YM15 'science project' DC Generator that I have purchased it's meant to be around 2400 RPM. My main 4JH4 TE it's about 1800- 2000 RPM.

The attraction I like about a DC Generator is it's frequency output, ie RPM, doesn't need to be constant. AC frequency via an Inverter. Good Inverters produce nice stable clean power. We all know shore power can vary in frequency and voltages, also AC generators, especially with loads coming on and off etc.

A little bit off this topic, but my idea is to only use Inverter power for all of my AC loads.

I want any generator or Shore power to only charge my batteries. My AC batt charger is an International multi voltage charger so I can plug it into any shore power any side of the pond without probs. Basically so my AC electrical system is one big UPS, so to speak.

Dockhead. I like and agree with your list. I would have included the fact that a single fuel source, which for most of us is diesel, is more convenient to source, store and as you mentioned after your list, safer.

I purchased a new 2YM15 for my 'Science project'. Obviously this is not a cheap option with not much change outta $6k. My thinking is I want to set myself up with good reliable and efficient set up upfront, to reduce (probably more delay) maintenance and running costs. Having both Yanmars my thoughts are some commonality of parts, ease to source parts and availability of knowledgeable mechanics etc.

I agree that fuel costs is not a huge priority. However my thinking is that this will become more important for me as time goes on as I know my income will obviously go down when I retire in the not too distant future. However what I consider to be important is minimizing fuel usage. This reduces the requirement for needing to visit the fuel dock/ sourcing and storing fuel and fuel types. This increases independence and time out etc, which is a priority for me.

I haven't got the alternators yet. I'm looking at my options, but thinking along the lines of large frame 'school bus' type units. Ecotech is on my list of possibles too.

Probably the ones I'm leaning towards at this stage are something like CE NIEHOFF 400 AMP 28v VOLTAGE GENERATOR 28 VOLT ALTERNATOR HET Military Truck types. Also found cheap on ebay. These are a lot of generator for not large money. They are Military surplus. They are Tough, brushless etc. The only disadvantage i can see is they are not small.

Another option could be some of the PMGs/PMAs available. One I'm looking at for around $450 24V, 2.8kW, max 1800 RPM. If I used these i would have to gear them slower, prob 2:1.

I'm thinking 2, for redundancy and to balance the load on the crankshaft by having them on opposite sides.

I have a general concept in my head but as things develop, and I learn more of course things will evolve.

So the remaining ingredients I see to make this work are-
1. brackets and pulleys mount alternator onto rear of motor,
2. Engine speed controller, and
3. Alternator regulator/ charge controller.

I have items 2 and 3 in mind from commercially available products.

ColdEh, just seen your recent posts. Great setup! Pretty much what I am thinking. Although I am thinking belts, which as you say have limitations, but are also have the advantage of being able to change and optimise speeds. Harley Davidson use them to drive their bikes so they cant be too bad. Your Alternator mounting frame looks like box tubing?

The bracketary and pulley, will of course will be a bit of work but not really rocket science. My thoughts are using steel box tubing welded. Most of which I can do. Pullies, commercially available multi ribbed belts. I will have to see if I need to do a shaft and pillow block bearing arrangement at the aft end. I think this should be ok without to keep things simple. Belt tension I intend to use a threaded stud pushing the two alternators apart. Alternators pivoting at the bottom where they mount on my box frame.

Alternator speed, I intend to maximize. This is one of the best ways to increase Alternator output. I will basically work on max Alt RPM of around 8-9,000 at max eng RPM (3600). I will go as big a pullies as I can physically fit in the space available to maximise the grip of the belts on the pullies.

I have sourced a lot of the components for this, like the 2YM15 already. However this will take me a while to get done on this as I'm currently working away to pay for all this stuff.

Just some of my crazy thoughts of what I think a good generator might be.

[john61ct]

Great input.

For me, since I see running the DC gennie just a few hours per week, I'm not too fussed about maximizing fuel efficiency.

Being as quiet as possible is more important. Rather, with least annoyance.

I find a low rpm to be much more tolerable than running fast.

Obviously the pulley ratio can handle setting the Alt rpm at whatever it wants. Does direct coupling mean no gearing?

The Eco-Tech being optimized for under 2000rpm seems fine for that, and the other large-frames I think don't need to run much higher.

So as long as the motor has good torque at low rpm I think that's where I want to stay. With pulley ratios and a bit oversized motor if I could get that down to 1000-1200? seems ideal for the noise factor.

I wish there were a way to inexpensively prototype this aspect, try out different motors for a given Alt model.

[Typhoon]

Originally Posted by john61ct

Great input.

For me, since I see running the DC gennie just a few hours per week, I'm not too fussed about maximizing fuel efficiency.

Being as quiet as possible is more important. Rather, with least annoyance.

I find a low rpm to be much more tolerable than running fast.

Obviously the pulley ratio can handle setting the Alt rpm at whatever it wants. Does direct coupling mean no gearing?

The Eco-Tech being optimized for under 2000rpm seems fine for that, and the other large-frames I think don't need to run much higher.

So as long as the motor has good torque at low rpm I think that's where I want to stay. With pulley ratios and a bit oversized motor if I could get that down to 1000-1200? seems ideal for the noise factor.

I wish there were a way to inexpensively prototype this aspect, try out different motors for a given Alt model.

Yes direct coupling means the alternator will run at the same rpm as the crank shaft of the motor.

One thing also to think about when you are designing these systems is the side load on the end of the crankshaft . This is not a big problem on a large engine but on a little engine if all the power the alternator is taking is going to side load the end of the crank shaft this may cause premature failure of the bearing . Just a consideration.

To overcome this you can put two alternators on , one on each side of the crank shaft to cancel out the stress on the bearing. This takes a lot of space and some imaginative engineering. Then you have two regulators , a combiner of some sort like a Balmar center-fielder , more wiring, more belts , all the more failure points . I know , I tried it before I found the Eco-Tech. It proved the simplest setup by far .

Regards John.

[a64pilot]

You can easily do belt drive, the attached photo is of the Nexgen 3.5 that Is belt driven. The key is pulley size, the bigger the pulley, the lower the load. Belts can be extremely long lasting and strong. Many if not most automotive double overhead camshaft autos cams are belt driven, Fiat first did that in the 70’s I think, and Kawasaki sold the first Kevlar tooted drive belt motorcycle in the 80’s after successfully road racing it.
The Military alternators I can attest to are very robust and extremely long lasting and likely were originally extremely expensive. Be tough to source a better alternator, however can they be had new?

[Q Xopa]

Almost direct coupling.

There are co axial gear boxes available. They are usually epicyclic gears, like these https://www.ebay.com/itm/5-1-Gearbox....c100752.m1982 .

But I did also see an interesting magnetic drive the other day
https://www.youtube.com/watch?time_c...&v=EAELukfr2oY .

I haven't looked into the specifics of prices, tq capacity, ratios etc, but I'm reasonably confident this is doable for those that are belt averse.

But Belts are not so flunky. The helicopters I work on use multi ribbed belts to drive the air conditioning compressors. If you use a common automotive type, they are readily available.

They are also easier to optimize the ratio to match the best operating RPMs of the engine and the Alternator. Ie if you want to have your generator engine running quietly at 1,000 - 1,200, or 2,400 for best efficiency but have your Alternator cranking out more Amps because it's spinning quicker this is possible.

Of course there are limits to this, like too small a pulley will not transmit a high torque, or physical space limiting pulley diameters etc. But chances are you can get a closer to optimum match with belts.

I'll have a bit of a look and see what i can see.

[warrior 90]

Originally Posted by a64pilot

One good thing about DC power production, there is no paralleling issues like there is with AC generators, you can run multiple DC sources without a problem.

That makes life a lot simpler


Q Xopa
A little bit off this topic, but my idea is to only use Inverter power for all of my AC loads.

I want any generator or Shore power to only charge my batteries. My AC batt charger is an International multi voltage charger so I can plug it into any shore power any side of the pond without probs. Basically so my AC electrical system is one big UPS, so to speak.

Yes, a giant Lithium!! UPS
I absolutly love this concept. A stable and constant quality power source that is sized for my needs and totally isolated from the charging issues.
The UPS can be charged with AC with a simple multi voltage charger. It can be charged with all DC sources. For me it´s the heart of the system.

THXs ColdEH Marine
I am sold on the ECO TECH
I am thinking of the pullys and belts they use for electric marine propulsion. It seems they use off shelf material that is easy adaptable to requiered RPMs of the driving motor.

KenBo that is a good price. I also liked the description of the features. Those alternators are proven tech in many applications
Very inspiring

Now I only need to keep my UPS happy and I have many options.
Since the UPS will also take care of the high start up loads of the AC and water maker/ bow thruster and windless. The generator can be sized a lot smaller. I only need to top off the batteries
=Less KVA
=Less weight
=Less space
=simple installation and trouble shooting
=$$$$

That makes a little Honda very attractive if the other sources like solar, wind, etc have a decent size. I admit on a smaller mono hull a large size solar is more complicated.
I like the simple Plug In to the AC shore power cable and the portability
However.... remains the exposure to the explosive gasoline fumes

On the other hand with the ECO TECH I have additional features like refrigeration and hot water when I used the main engine as a generator.
More reliable and less noise
That seems to be the best over all solution in my point of view

[Q Xopa]

This example does say new? But as you say these would have been horrendously expensive originally, guessing I'd say $3k?

https://www.ebay.com/itm/CE-NIEHOFF-....c100012.m1985

[Cheechako]

Northern Lights. Definitely not Panda or Westerbeke. And a charger to get to 12v.

[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.