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Old 27-03-2017, 05:26   #1
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diesel Power generator or Solars+bigger alternator

I wonder if not to buy separate generator and instead of it put stronger engines generator (alternator) like 150 A with regulator +solar 500W.
I have no A/C on boat so main power consumption comes from autopilot and fridge.
Separate generator costs more and takes some space. Plus is that takes less fuel. Still it is limited anyway (200L) plus 50 extra.
Anyway usually we use engine from time to time.
Power bank is 3x140 for hotel.
I wonder if 500W of solars and stronger alternator in case of clouds will work for 3 weeks ?
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Old 27-03-2017, 05:41   #2
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Re: diesel Power generator or Solars+bigger alternator

More info required, for instance size and type of boat, power consumption (assuming battery monitor installed), and useage details.

If this is a 30' racer, go for shore power for sure
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Old 27-03-2017, 05:43   #3
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Re: diesel Power generator or Solars+bigger alternator

Yes, if your propulsion engine runs regularly, do a large-frame HO alt (Leece-Neville, Delco or Balmar) + serpentine belt + MC-614 VR conversion or addition, pulley ratio set to (be capable of) output 70-80% of rated amps at the RPM range you usually run it parked, wired direct to biggest, most used bank.

Maybe not much cheaper than a gennie, but lots lighter and simpler.

Adjust the actual output level using the VR "belt saver" and "small engine" modes, unless your low-RPM HP at alt full output is manageable.

Also optimize the Voltage setpoints for your bank's chemistry.
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Old 27-03-2017, 05:46   #4
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Re: diesel Power generator or Solars+bigger alternator

Still need as much solar as fits for the "long tail" to 100% for bank longevity, alt will only get you into Absorption, do that in the AM, depending on sunshine, long enough to be sure your Solar will get there by 4-5pm at the latest.
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Old 27-03-2017, 06:28   #5
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Re: diesel Power generator or Solars+bigger alternator

If you aren't running air/con or other power hungry devices, 500w solar is likely all you will need. You probably don't even need to upgrade the alternator if its only a few times a year you use it for charging.

But before recommending, do an energy audit. Figure out how many amp-hrs each device will use per day (you may need separate calcs for at anchor vs on a crossing).

Assume the solar will generate it's rated output for maybe 4hrs per day and make sure the battery bank will hold your daily consumption in about 1/3 of it's rated amp-hr. (that will actually give you 3-4 days to carry you over on cloudy days.)
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Old 27-03-2017, 06:46   #6
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Re: diesel Power generator or Solars+bigger alternator

420 AH of flooded batteries, I doubt he would have much use for a large frame alt? Even if pretty deeply discharged, what is the banks acceptance rate after say 20 min of charging?
Large frame Alts come into their own if you plan on running big load off of one, air compressor, air conditioning etc.
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Old 27-03-2017, 08:05   #7
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Re: diesel Power generator or Solars+bigger alternator

IMO if you're going to upgrade the alt, you need the good VR anyway, it's not much more money to go bigger on the alt, I picked up a 320A LN 4000 series firetruck unit off eBay, as new still in the box guaranteed six months, total cost $180 delivered.

Using a lower fraction of possible output is a good thing, rather than stressing a smaller one.

Small-frame alts re-wound to put out a lot of amps at low rpm often don't last long, especially without careful "belt manager" type tuning wrt temps.

My way, if he needs to expand the bank later on, even 5-10 years later, no need to upgrade further.

Engine runtimes dedicated to charging should be minimized, higher load better for most motors anyway.

The OP question was "as opposed to a separate gennie", my main point was no, IMO bigger/better alt way to go.

But if the large frame alt requires metal/belt/pulley work OP can't get done at a reasonable price, and a lesser upgrade will cover his needs, then yes you're right he can save money that way if he thinks my above reasoning isn't worth it.
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Old 27-03-2017, 08:24   #8
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Re: diesel Power generator or Solars+bigger alternator

IC engines are the least money-efficient way to get power to your batteries, unless you're running them at full load.

Diesels prefer loads, but you can't necessarily make that happen always (have it fully loaded).

Solar is silent, operates when you don't care to be doing anything, and, overall, will make their money back quickly when compared to the cost of generating those amps via a diesel, whether dedicated genset or hang-on to some other diesel tasked and doing some other chore.

Wind comes in a close second, as it will work in the dark. It takes someplace to mount it, as does the solar, and YMMV as to what you like or don't about the available options.

As to the solar, if you have acres of real estate, get the cheapest watts you can and wire appropriately to the controller you choose. However, if real estate is an issue, there is nothing better than a Sunpower panel of whatever size you choose.

I just finished installing - less than a week into spring - two 360s where I'd previously had 3 panels putting out 370w; in overcast conditions, and the sun angled such that my whip antenna shadow went from one corner to the opposite corner on one of the panels (net loss 2A) I was showing 32A; in the summer I expect I'll see 50 or better amps. Worth the much higher watt cost to me, as that's all the room I had. 22.something % efficient makes for a very much smaller footprint than 15%, e.g.

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Old 27-03-2017, 11:57   #9
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Re: diesel Power generator or Solars+bigger alternator

The boat is 46f.
I know that that I have to reduce the power consumption, so no A/C or deep freezer.
Fo sure he auto pilot will work a lot, as well as the chart plotter.
During the sun also desolator - I had it on boat working well and doing during day enough water for whole next day.
Sunpower gives 360 W from 12,x1m area. I want to put 2 and got 720W.
Even sun is not clear it gives some power.
Has anybody tried Watt&Sea Hydrogenerator?
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Old 27-03-2017, 11:57   #10
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Re: diesel Power generator or Solars+bigger alternator

Quote:
Originally Posted by Freshman View Post
I wonder if not to buy separate generator and instead of it put stronger engines generator (alternator) like 150 A with regulator +solar 500W.
I have no A/C on boat so main power consumption comes from autopilot and fridge.
Separate generator costs more and takes some space. Plus is that takes less fuel. Still it is limited anyway (200L) plus 50 extra.
Anyway usually we use engine from time to time.
Power bank is 3x140 for hotel.
I wonder if 500W of solars and stronger alternator in case of clouds will work for 3 weeks ?
Electromaax has some high output Alternators which may cater to your needs, 12V 215A and 24V 165A. Maybe sufficient if you are doing short runs for boost charging.

Here is the link for more info.,

https://www.electromaax.com/product-...or-generators/
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Old 27-03-2017, 12:31   #11
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Re: diesel Power generator or Solars+bigger alternator

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Originally Posted by a64pilot View Post
420 AH of flooded batteries, I doubt he would have much use for a large frame alt? Even if pretty deeply discharged, what is the banks acceptance rate after say 20 min of charging?
Large frame Alts come into their own if you plan on running big load off of one, air compressor, air conditioning etc.
This is a good point, indeed. Many would suggest not putting in more than 20% of capacity into a flooded lead acid bank. That's only 80 amps in this case. Even a 120 amp small case alt, de-rated to 80 could probably handle this for 2 hours (50% to 85% SOC), no?

I vote solar first, then alt if still required. A diesel generator when you don't have an AC, dive compressor, electric oven/stove, or a washing machine just seems overkill.
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Old 27-03-2017, 12:40   #12
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Re: diesel Power generator or Solars+bigger alternator

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Originally Posted by fallingeggs View Post
This is a good point, indeed. Many would suggest not putting in more than 20% of capacity into a flooded lead acid bank. That's only 80 amps in this case. Even a 120 amp small case alt, de-rated to 80 could probably handle this for 2 hours (50% to 85% SOC), no?

I vote solar first, then alt if still required. A diesel generator when you don't have an AC, dive compressor, electric oven/stove, or a washing machine just seems overkill.
I have 100amp Mark Grasser alt. With 440amp/hr bank the most of seen going in is approx 70a first thing in the morning.
Without upgrading to a serpentine belt set up I wouldn't want the batteries pulling more as its really hard on the v belt.


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Old 27-03-2017, 22:22   #13
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Re: diesel Power generator or Solars+bigger alternator

Years ago I added my two 60W panels and have them on a system of adjustable supports near the stern, one on each quarter. I can adjust them to nearly any angle. They are pretty big and heavy, I'd guess 22"x47" or so and I never got more than 8A total from both, in bright sunshine with no shading, optimally adjusted to sun angle.

Solar becomes a little hobby for me where, to get any meaningful power from them I need to adjust them every 2 hours during the day as the boat swings around with the wind, the rigging casts shade, and the sun moves.

You can't beat a generator when your batteries are down to 50%. It lets you be much more flexible in when and what you want to run. Microwave, hot water heater, watermaker and recharge batteries all at same time, first thing in the morning and after 4PM, without heating and depreciating the main engine - that's what I want to do and solar, even if I was to 4x the area and double my battery bank, can't do that.
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Old 27-03-2017, 22:41   #14
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Re: diesel Power generator or Solars+bigger alternator

I run a double door reefer and 2 small freezers plus all my cabin lights are ac. I run it all thru the inverter. With a bigger alternator on one of the mains I can keep the batteries up w/o running a generator. Saving a couple gallons/hour. I have several banks of 8dds so I can go a couple days or more on the hook w/o charging. When I make water, I run a generator and time that to needing the water heater. No ac, don't like hot places.
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Old 28-03-2017, 01:01   #15
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Re: diesel Power generator or Solars+bigger alternator

We still need to know what your power consumption is. Without that it's all guess work.
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