WHAT IS A GOOD GENERATOR ??

[warrior 90]

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.

I would say full load at max torque/fuel efficiency ratio takes care of the carbon built up and keeps the run time at the sweet spot

Question: what size alternator is best to what size engine ?
The smaller the engine ....
less weight
less space
less $$$ fuel-maintanance

[warrior 90]

Originally Posted by ColdEh Marine

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.

I am doing fine with 1 ECO-TECH alternator. What would You consider the best engine for this alternator ?

At this moment my main engine is a Westerbeke 30B/27Hp and my plans are for a UPS style concept with 2 banks total 8 -1000 amp LFP
Of course a second alternator and 550 amp would be great. I am calculating a max of 100 amp for the AC.

My biggest problem is space and weight. (Small Cat 36 foot full time live aboard)
I can fit 600 watt solar but with second engine I am concerned about performance. I could also fit another 600 watts of solar but the requiered custom structure has also a substancial weight and cost

[john61ct]

Originally Posted by newhaul

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.

If we're talking 3 minutes at a time, 15 minutes per week, not worth it.

Question stands, short stints to burn/blow out carbon, need to be under load as long as rest of the time is?

I have to believe, no.

[john61ct]

Originally Posted by warrior 90

for a UPS style concept

I'm not getting the meaning intended here if any.

UPS means batts are standby only, used very rarely only for just a few minutes, rest of the time grid mains is the power source.

I see no parallel with the deep cycling use cases being discussed here, other than batteries are involved?

[john61ct]

Originally Posted by warrior 90

I would say full load at max torque/fuel efficiency ratio takes care of the carbon built up and keeps the run time at the sweet spot

Question: what size alternator is best to what size engine ?
The smaller the engine ....
less weight
less space
less $$$ fuel-maintanance

As I said, my priority is to run the engine at as low an rpm as possible to handle the required torque, so my question still stands.

Yes if the boat's too small size requires a smaller engine, then I will need to compromise on that

but never mind fuel efficiency, or any other more theoretical efficiency, not even on my list of issues.

[newhaul]

Originally Posted by john61ct

If we're talking 3 minutes at a time, 15 minutes per week, not worth it.

Question stands, short stints to burn/blow out carbon, need to be under load as long as rest of the time is?

I have to believe, no.

John it was in ref to another poster. Also we would be talking 20 to 30 min each time the engine was running at higher rpm .

Btw not my setup yet. Won't do electric hw till I go lifepo4

Edit. I just looked back and my post you replied to was in direct reference to your post about high rpm run with minimal load. 2 700 watt elements would place approx 100 amp load on an alternator .

[missourisailor]

Originally Posted by john61ct

I'm not getting the meaning intended here if any.

UPS means batts are standby only, used very rarely only for just a few minutes, rest of the time grid mains is the power source.

I see no parallel with the deep cycling use cases being discussed here, other than batteries are involved?

On a true industrial (whole building) UPS, the building is running off of an inverter 100% of the time. Which is getting it's input power from batteries. Which their charge source is connected to the "grid".

The little UPS you have connected to your computer operates the same way.

Most building UPS's have a battery bank with only enough capacity to power the building for a few minutes. Which is enough time for the back up generator to start and come on line.


I may be wrong but I think that "warrior 90" is talking about all AC power coming from a inverter. And Ship to Shore power doing nothing but powering a battery charger.

Which is not a bad way to go if you don't have heavy AC loads.

[Q Xopa]

OK, a bit off topic again, but seeing it is being mentioned.

All true about the usual way UPSs are utilized.

Now picture a UPS with a giant battery, not just big enough for a few minutes until you can shut your household PC down, or start up your back up generator online.

So whatever your normal AC loads you want to run, whether it be Air conditioners (this is obviously a big set up), iPad charges, induction cook tops or whatever. if you have big enough Invertors and battery capacity you can run all these devices.

Realistically this is going to be a Lithium bank, with big invertors etc

Obviously the batteries will need re charging at some point. This where our shore power or AC or DC generator come in. In this case if we use a multi voltage charger, like say Sterling AC batt chargers. PS I'm in no way affiliated.

The advantage of doing it this way are-
1. Good Invertors are nice 'clean' power, voltage and frequency stable not like most shore power or generators, and
2. The battery bank will absorb and smooth many transient loads and surges.

Taking the concept a little further of 'Internationalizing' a global cruising boat electrical system. The US 110V standards will specify larger wires than 240V European. Obviously 110V appliances need more Amps and therefore larger wires for a similar powered appliance. Worthwhile considering for those of us doing elec sys refits.

Back to generators, the usual answer is to size it to your load. So an idling DC generator, to keep it quiet. Most Generator shops will tell us to get a smaller generator that works harder closer to it's designed operating load range. Of course it will be noisy because it working harder than the bigger idling one. Hmm, again not the desired result. Ideally we need to match the diesels load and RPMs and the Generator capacity as closely as we can to our requirements.

I wouldn't get too caught up on things not being ideal. Operate the way you want to. We dont want be a slave to our machines, they are expendable for our purpose. Many, not just cruisers, but indeed the majority of the population abuse their machines every which way and get away with it for the most part quite fine, in their blissful ignorance. The trouble for us that we know too much for our own good. Its a burden. Just me being a bit too pedantic pointing out the ideal, sorry. It's not a perfect world we live in.

I just like to learn from you guys on here.

I would just run your generator slowly and quietly.

As another little aside, the old Lister CS single cylinder 9 hp big tall green Diesels with 2 heavy spoke wheel flywheels. These Diesels ran for ever, some literally non stop for decades. They ran at around 700 RPM. This is the concept you need. Practically however space and weight wise this is not a viable option, but seeing the question was asked.

Keep the good ideas and dialogue coming.

[a64pilot]

To “burn” off the carbon, you need heat, RPM at little to no load does not provide much heat, an engine at full throttle and loaded so that it’s at it peak HP does.
If your going to run the engine at lower RPM, your not going to get much power out of it and therefore you will have a bigger, heavier engine than you have to have. You’ll have a 40 HP engine say, and only 10 of it useable for example.
Not much is smoother and quieter than a good Onan or NL generator running between 1500 and 1800 RPM, and they run for tens of thousands of hours, so steady RPM can’t be too bad for them. I’d try to duplicate the running profile that Onan, NL and others use, cause it seems to work for years and tens of thousands of hours. They just may know what they are doing.
You want to size the engine to the generator and the two of them to the load.
As has been said a great thing about the new inverters with the assist is that now you don’t have to size a generator for the biggest surge it will ever see, you can now size it correctly for its average load, and save a bunch of weight and space, and money.

[newhaul]

Add this to your dc genset.

https://www.altestore.com/store/inve...UaAhmREALw_wcB

[Q Xopa]

Yes agreed. Gen auto start is a great concept. There are many different flavors.

I can also see times they are not so convenient, turning your generator on in the middle of the night and waking everyone etc. I guess they have manual over rides or can be switched off.

I'm also wary of how much I could trust or rely on them. How reliable they are? I suspect potentially not totally.

Having said that I'm sure I am most definitely far more unreliable. It would be good to take the human intervention factor out of the equation as much as possible. We people are usually the weak link, speaking for myself anyways.

[newhaul]

Originally Posted by Q Xopa

Yes agreed. Gen auto start is a great concept. There are many different flavors.

I can also see times they are not so convenient, turning your generator on in the middle of the night and waking everyone etc. I guess they have manual over rides or can be switched off.

I'm also wary of how much I could trust or rely on them. How reliable they are? I suspect potentially not totally.

Having said that I'm sure I am most definitely far more unreliable. It would be good to take the human intervention factor out of the equation as much as possible. We people are usually the weak link, speaking for myself anyways.

the one I linked to has that nighttime quiet hours feature programmable as part of the overall algorithm. Seems like a great addition to the generator and lifepo4 scheme

[john61ct]

My proposed use case in the genesis of the DC gennies aspect here, was little or no inverter usage, only where really necessary, maybe a small microwave. Which isn't really relevant, but.

As to my setup's rpm solution:

Size the smallest motor that will spin the Eco-Tech max output at low rpm.

Size the pulleys for that, within the context of not causing the Eco-tech any harm from high rpms at load for engine maintenance.

Given runtimes average one hour per session, total 5 hours per week, 95% at normal low rpm,

then motor will run fully loaded for 15min once a week, rather than doing 3min per session, since getting up to high temps is required.

Is longer time required?

[warrior 90]

Originally Posted by newhaul

Add this to your dc genset.

https://www.altestore.com/store/inve...UaAhmREALw_wcB

Mmm Yummy, user defined programming according to battery state of charge with timer
I love that part of the menu for dessert
But I am still too busy with digesting the big hunks
THKs for the info. Wasn´t aware of this new jewel from Xantrex.
Now I have to watch a lot less. I hear the gen when I am down to a certain voltage and with a big LFP bank I can decide when to run the gen.
Only thing I could not find is ?? if the automatic engine start up includes engine preheat in case of diesel engine.
Would be great.Than I could maybe hack the software and use it for the main engine in case I decide to charge by DC alternator on main engine and save the weight and all the hassle of a second engine on board ???
Hahaha, otherwise I would have to use my automatic finger switch

163 $ won´t make me rich neigther poor

[a64pilot]

Five hours total per week, skip the generator and just put the big alt on the propulsion motor.
Although I plan on eight hours a week so I guess that isn’t that much different. I plan on two runs a week, not every day.
I see the requirement of a DC genny for someone like Dockhead who won’t put panels on their boat but wants to cook with electricity.
That means generator to me of some kind.
Regular cruisers electric needs can be met with panels, and a big alternator or a Honda etc.

You can load an engine enough at 1500 RPM so that it doesn’t need any special high power runs or blowing out etc.
Usually takes 1000 RPM for a motor to smooth out and 1200 is nice, however 1500 is just a smidge more, so why not run at 1500? Forget any special considerations?
50 Hz low speed generators Onan and NL run at 1500 RPM, 60Hz ones 1800.