DC genset to power boat.

[Wind River]

Originally Posted by a64pilot

Side load on a loose belt is low, OK not zero, but well within tolerable limits I'm sure, High side loads come from the excess tension required to keep V belts from slipping.
Or if you felt the need, you could direct drive a shaft supported by pillow block bearings and mount the pulleys on the shaft, the pillow block bearings would then carry the side load, and the engine would have none, point being, don't let the concern of side load stop you, it's not hard to manage.
Most small engines are designed to handle quite a bit of side load as they are meant to be used quite often to drive components like pumps etc via a belt.
Actually the shaft may be useful to drive several components off of different pulley's, shaft giving you space to mount several, I guess you could even use an AC clutch to engage different drives if you liked, depends on how complicated and expensive you want to make the thing.

Myself I don't have the time, time is why I abandoned the idea and just bought something.


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I was just typing out the pillow block idea but you beat me to it!
Also, someone earlier mentioned the power take off units offered by R.C. Plath Company. They are similar to this idea.

I agree this side load problem can be overcome and that would let me overdrive a "less expensive" alternator (maybe even two!) to achieve the output I need reliably.

[DotDun]

Originally Posted by a64pilot

Side load on a loose belt is low, OK not zero, but well within tolerable limits I'm sure, High side loads come from the excess tension required to keep V belts from slipping.
Or if you felt the need, you could direct drive a shaft supported by pillow block bearings and mount the pulleys on the shaft, the pillow block bearings would then carry the side load, and the engine would have none, point being, don't let the concern of side load stop you, it's not hard to manage.
Most small engines are designed to handle quite a bit of side load as they are meant to be used quite often to drive components like pumps etc via a belt.
Actually the shaft may be useful to drive several components off of different pulley's, shaft giving you space to mount several, I guess you could even use an AC clutch to engage different drives if you liked, depends on how complicated and expensive you want to make the thing.

Myself I don't have the time, time is why I abandoned the idea and just bought something.


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Side load is much higher from a fully engaged alternator than from a properly tensioned v-belt with no power load. Engine manufacturers publish side load limits.

[ColdEH]

Originally Posted by Wind River

Neither of the engines I have are marinized. I will be rebuilding whichever one I choose to use and adding the water pump">raw water pump and heat exchanger. I have a Ford Lehmen as my main engine so I am not partial to either of the small diesels I have. I just want to use the best one for the job.

I cant seem to find a hp rating or displacement of your Yanmar 3GH. Any idea what it is?

The Eco Tech alternator really seems to be in a class of its own.

It has the hp right on the tag , I think it is 14 hp or very close to that .

Yeah the Echo Tech is something . Read this from there Testimonials.

"August 2013

Six years ago I chose an Eco-Tech Alternator for continuous use in a hydropower application both because of its high power output at low RPM, and also because it had the best efficiency on the market. Fifty thousand hours later, (and 75,000 kWh) the Eco-Tech delivers reliable and efficient power. Today I ordered bearings and brushes for the next eight years!

Matt
Bonners Ferry, Idaho "

Don't think I will use it that much

Regards

.

[a64pilot]

We'll see there is your catch, your not pulling 200 amps or so out of a properly tensioned V belt. Even a dual belt system I bet you have to over tighten to get that kind of amps. My stock 80 amp ate belts, even Greenstripe and Gatorback belts. So when I went to 140 amp Alt I went to a 10 rib serpentine. Now I can run low belt tension and at least twice the amps. I bet my side load is lower now than it was stock because I had to way over tension the belt to keep from eating it up


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[exMaggieDrum]

Troll note: some of the BS written on here just fries my gizzard! I won't rant on some of the specifics but I almost get sick reading some of it. Readers beware!

Factoid: The PO of my new/old boat put in a Balmar PC-750 DC genset. It has a Balmar large frame 275A alternator. Originally it came with a Balmar 612 regulator. It has a completely marinized Yanmar 2 cylinder diesel with alarms and a remote panel with a tach, voltmeter, etc. Very nice unit but well over 200#. It does not have a sound shield but is not terribly noisy nor does it vibrate any worse than the Perkins main engine. It also came with a high volume salt water pump to drive a watermaker. The water pump is about 30# by itself. The watermaker was never installed. It puts out gobs of 12v DC amps at a constant RPM, although there is a speed control to vary it if need be. The alternator is direct drive so no belts or pulleys. Very nicely engineered and executed. I am not sure why they did not continue to make them but stopped several years ago.

I actually may sell the genset as I don't want that much weight where it is and I don't have room for it anywhere else. I have massive solar and would use a Honda gas genset for emergencies. I also have a Balmar 100A alternator on the main engine. My only problem is to figure out how to get it out of the engine room as it is to the stern of the main. I will have to disassemble it for sure. But it is a reliable and sturdy unit with parts easily available so I may just keep it.

[CGirvan]

I wonder has anyone built there own DC generator using a permanent magnet motor rather than an alternator? My understanding (could very well be wrong) is that a pm motor driven will produce power and their efficiency is much higher than that of most alternators.

[a64pilot]

Here is a link to the manual for that Balmar Generator
http://www.balmar.net/PDF/Genset-Wat...r%20Manual.pdf

I wonder why it was discontinued? Seems to me coupling a watermaker pump is a good idea, make water and charge batteries? And if you assume 250 amp at 14V, that's a 3500W generator, which is a lot. Maybe it was too big? Most banks couldn't accept that high a charge rate?

[a64pilot]

Originally Posted by CGirvan

I wonder has anyone built there own DC generator using a permanent magnet motor rather than an alternator? My understanding (could very well be wrong) is that a pm motor driven will produce power and their efficiency is much higher than that of most alternators.

I don't know about efficiency, but a PM generator will run as a motor, ever had to flash the field on an old Volkswagon generator? But they were big, heavy and had low power output for their size and weight.

[Cheechako]

Originally Posted by CGirvan

I wonder has anyone built there own DC generator using a permanent magnet motor rather than an alternator? My understanding (could very well be wrong) is that a pm motor driven will produce power and their efficiency is much higher than that of most alternators.

I have not, but what you are talking about is essentially the generator used on cars prior to the late 50's. In my experience they were much more problematic at varying rpms than alternators,heavier and lower output... not to mention heat issues at higher output.

[Cheechako]

Originally Posted by a64pilot

Here is a link to the manual for that Balmar Generator
www.balmar.net/PDF/Genset-Watermaker%20Manual.pdf

I wonder why it was discontinued? Seems to me coupling a watermaker pump is a good idea, make water and charge batteries? And if you assume 250 amp at 14V, that's a 3500W generator, which is a lot. Maybe it was too big? Most banks couldn't accept that high a charge rate?

May just didn't fit into their profit margins etc. Hard to ship, complex to assemble compared with an alternator. Sometimes you just have to focus on what you do best. ?
BIg? maybe... I did find that 150 amps you could only pound into your batteries for 15-20 mins or so anyway.

[ColdEH]

Originally Posted by Hobie_ind

That's an awesome setup! Thanks.


Just one thought on your setup. A 'splash hood' over the alternator may be something to look at when you start using the watermaker. Will any inadvertent hose leaks, etc drip into the alternator with the current configuration?

You've certainly given me some food for thought!

Thanks,
Mark

Good of you to notice. I actually did add an aluminium splash shield before I installed the unit in my boat , just in case .

Regards

[yvest]

About DC generators, how come Polar Power DC generators are so lighter than Fischer Panda ones ?

For instance :
Fischer Panda AGT-DC 8000 : 6.4 kW : 160 kg
Polar Power 8080Y-2TNV70 6 kW : 89 kg
Polar Power 8220I-3CA1 10 kW : 119 kg

Base engine ? Weight counted differently ?

[Dockhead]

Originally Posted by yvest

About DC generators, how come Polar Power DC generators are so lighter than Fischer Panda ones ?

For instance :
Fischer Panda AGT-DC 8000 : 6.4 kW : 160 kg
Polar Power 8080Y-2TNV70 6 kW : 89 kg
Polar Power 8220I-3CA1 10 kW : 119 kg

Base engine ? Weight counted differently ?

FP is AC.
FP is marinized (so weight includes heatexchanger, exhaust elbow, etc.)

FP has a sound enclosure.


PP is DC, not marinized, no sound enclosure.

[RaymondR]

The large diameter DC generator on the PP DC generator will be much lighter than the AC alternator on the FP. One of the reasons inverter AC gensets are so light in comparison to the older conventional AC induction gensets.

[yvest]

Originally Posted by Dockhead

FP is AC.
FP is marinized (so weight includes heatexchanger, exhaust elbow, etc.)

FP has a sound enclosure.


PP is DC, not marinized, no sound enclosure.

No, the FP is also DC :
https://www.fischerpanda.de/Generato..._400_Hz_66.htm

And I understand that the FP has a shared water cooled system for the engine and the alternator, whereas for the PP only the engine is watercooled, option for the alternator.

As to the PP being not marinized, not sure, Marine application is listed, and indeed the sound insulation isn't counted, but still, from 89kg to 160 seems like a huge difference..