12V DC Genset

michaf

michaf

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Hello boating bros,

me scratching head. We've been boating for several years now, we know now we will be cruising longer. So far no genset has been fine. But I'm starting to look for one. All in our boat is 12v, except cooker which is gas. We already have 400w of solar.

So what I want is a DC gen that will pump like 160 amps in our battery bank. Reason why I think DC is better for us is multiple, but anyway, this is what I want.

And so looking at what is available:

Fisher Panda

http://fischerpanda.com/marinegen/dc-generators/agtpm4

However looking at this post, I'm not really motivated http://www.ybw.com/forums/images/icons/icon9.png

http://www.sailwhisper.com/logs/news_20080225.php

Whisperpower

http://www.whisperpower.com/4/2/156...mmable-rpm)/dc-generator-24v-150a-marine.html

Only 24v...

HFL

http://hflmarine.com/products-page/d-c-chargers/d-c-traveller/

Could be something...

Polar DC Marine

http://www.polardcmarine.com/cms/product-info/generators/volvo-based/pdc-8080vp-20/

Could be something too...

Any experience anyone? Any other brand? Comments?

Thanks!
 
I'd prefer a 230v AC genset powering your existing 230v battery charger, but you said you have already decided on the 12v route. FWIW I had HFL genset on Fairline 42 years ago and liked it. only problem was poor international spares network - I could not get HFL serviced in France/Mediterranean
 
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there's a world of difference between a genny just pushing 160A into your battery banks, and a purpose-built battery charger doing similar but intelligently.


To charge batteries as fully as poss, you need to alter the input at the various states of charge, and some battery chargers have up to 8 stages. Various types of battery also need differing charge profiles.


A 240v charger, as JFM points out, would be more versatile, and would need less heavy duty cabling architecture. 240v would also provide for equipment for which no 12v alternative exists.


I had an HFL (Mitsubishi 3 cyl diesel engine) running a 7 KW 240v genny. The more I used it, the better it ran.
 
Well your engine alternators are doing just this, charging at 80amps for example. A DC gen will do the same.

Batteries can take a lot of charge. Take for example Optima Yellows will take as quoted "No current limit as long as battery temperature remains below 125°F (51.7°C)." for charging.

What is important is to switch off the charge when starting the float phase.

In my case I could top up my batteries in an hour and let the solar do the float for the rest of the day. That's an hour a day to run everything, from coffee machine to water pumps etc (my boat is brand new so all 12v stuff is highly efficient).

Here's an article from Fisher Panda that illustrates why a DC Gen with a decent battery bank is a viable option:

http://www.fischerpanda.co.uk/article9.html

The fondamental idea here is that nearly ALL of the Gen's output goes into stored energy. You also have to take into account that a DC Gen will run at whatever speed is needed to produce what is needed.

As for cabling there would be about two meters from the Genset to the bank. Not so much a problem.
 
michaf said:
Well your engine alternators are doing just this, charging at 80amps for example. A DC gen will do the same.
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Hang on - you can get intelligent black boxes twixt alternator output and your batteries (I have them; there was a recent thread)

michaf said:
The fondamental idea here is that nearly ALL of the Gen's output goes into stored energy.
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That is a great idea in concept. It means the genset need only provide an output to match you average load rahter than your peak load, adjust for the % of time you want silent running. But remember this needs a lot of batteries!


michaf said:
You also have to take into account that a DC Gen will run at whatever speed is needed to produce what is needed.
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Careful about that. A constant 1500rpm is much preferred by many to a genset that revs up randomly, and the smaller the boat the more you'll hear it...
 
Nick_H said:
This is not a reccomendation because i've never used one, but just for completeness, have you considered a fuel cell? They output at 14.2V I believe, and can be set to start up at 12.3V, so will keep your batteries topped up. They're small, light and silent. The big issue is you have to carry the methanol around.

http://www.fuelcellsystems.co.uk/fcapplications/marine-fuel-cells/
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Interesting Nick. I was wondering about using as a partial batt charger at night so genset doesn't auto-start at 5am if the fridge load is heavy. From a quick look I think they offer the following, just as an example:

one "210" unit @£5000
4.5amps of charge current 24v DC
Methanol usage about 2.5litres per day =£20
To have a season's worth you'll be carrying 100 litres = 10x10 litre cartons = £800
 
Best thing i can recommend is to use an alternator, since you already have the engine to power it.

Yes, i work for Sterling Power, so i will try not to push our products and say there are other options - not looking for a plug.

If it was my set up, i would use one of our 200amp alternators, with a regulator that will give you the 4 step charge. you will need to up your belt system if you have the old style v belt as they simply cant take the amount of grunt on just one, but a twin pulley will be fine.

One thing to remember is with lead batteries is to charge at 10% of their amp hour capacity. so for a typical 400ah set up you can only really use 40a to charge them. so with the OP's request to have 160a is assuming he has 1600ah of batteries if he was really to use that much - not doubting that he doesnt but just in case! ;)
 
michaf said:
Ok, so I can feel some resistance here:D, not really surprised. So let's start from the basic wishes. What would you get in manner to put 150 amps in a 440 ah bank within an hour?
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I assume you mean @12vdc? I'd have a big mastervolt inverter/charger. This would need <10 amps of 230v AC, so a nice 3.5 kva small genset would be grand. And I could boil a kettle when I'm done :-)

Wofford UK I dont think running a main engine lakes sense at all here, for many reasons. Also the boat in this case doesn't have 1600AH of battery afaik. I do not stick to 10% charge rate on my boats (for 12 years+) and have never had a problem. I want them charged MUCH faster than that to minimise my genset run time, and maximise my period of silent running. To hell with babying batteries: I'm happy to chuck them out after a couple of years and get new ones, and they are 100% recycled
 
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at the end of the day, you can only throw in a battery what it needs yes you can boost the current by upping the voltage but only to a point. they may accept more than 10% but not for a very long time, before the charge curve drops away.
 
wofforduk said:
they may accept more than 10% but not for a very long time, before the charge curve drops away.
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But that is the whole point. On a boat, you let them discharge deeply, say 80% discharged., so you're miles away from he point where the charge curve drops away. At this deeply discharged point in the cycle you want to chuck waaaay more than 10% into them, and they can take it, otherwise you'll be running a genset for ages and ages. Sure, when they become 70% charged then the charge they will take reduces, but for the earlier period of getting them from 20 to 70 you want to blast them, and therefore minimise your non silent hours

I have Mastervolt's fancy electronics and when I'm sitting at anchor for a few days I let them fall to 80% discharged and I charge them back up to 20% discharged, and then I stop. No point in doing that last 20% every time, when you're not on shorepower. Of course, after 5 or 6 cycles of that they usually end up being 100% charged by engine alternators or shorepower

Anyway, this is why I'd always specify a charger at more like 35% than 10%
 
doubt your batteries will last too long if you take them to 80% too often! but thats your choice :)

in any case, if you try to charge a battery, lets say a normal 110ah open lead, it will only take in a set amount of juice, even at a boosted voltage. so yes you will probably get 15a going into the battery for a short period of time (over the 10% guideline) however you could connect that up to a 1,000 amp alternator but it would still only take a charge of 15a

reminds me of a customer who was complaining that he wasnt getting 200 amps of charge into his bank of 300ah batteries.... have to laugh, especially when he has a 170a alternator!
 
This is a AC one to power up your presumed " smart charger / batt conditioner " ??
http://www.nextgenerationpower.com/Info/Support/3-5Specs.pdf
Approx less than $ 5K
BTW for the past 10 y my FP 4-2 AC has been fine - sure by its compacted nature - PITA to work on .
I too have seen folks slagging em off on the net -guess maybe I,am lucky? Dunno?
As other have said a little AC is nice on bord .
We do anchor off when we go off touring so find a little Geny v useful .
Another little - Un
http://www.yachtsupplydepot.com/ele...sorlp1-3-5kw-marine-generator/prod_72247.html
 
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Gonna have to backup jfm on the charging rate. My boat came standard with 80 amp charger with a 440 ah bank 12v and yes it does take the full 80 amps. As already sated have a look at the specs of these batteries, they have no limit in charging rates as long as the temp is right:

http://optimabatteries.com.au/wp-content/uploads/2012/07/Group-D27F-YellowTop.pdf

Also running my cummins to charge my batteries is a no.

So coming back to an ac genset what you guys suggest is I need 12x160 = I need 1920 watts so 2kw genset, so with margin 3kw. Added to that some beefy chargers. Is that right?
 
the only proviso I have is whether a diesel generator engine running at a maximum of 2/3 capacity for - say - half the time, and much less than that when the charge to the batteries levels off, is going to be happy and long-lifed. There are issues such bore -glazing especially at light load and extended tickover.

If you can add extra 240v load when the charger moves into float mode, that would give the engine more work to do and make it run well. Perhaps something as simple as a fan heater would do.
 
Something like a Lifeline AGM will accept charge at a much higher rate than a standard lead/acid leisure battery.
With a lead/acid battery, discharged to 50% and recharged to 80%, you will average about 0.25 x capacity in terms of amps you can put back in. I.e. 100A if you have a 400AH battery bank.

So with a lead/acid battery bank if you discharge to 50% and charge to 75% the best you can do is about 1hour generator time.

With AGMs you can typically pump the amps in at 4 times the rate or more if you have the set up to do it.
I.e. 15 minutes of generator time.

DC Generators make sense from a fuel efficiency perspective - you can adjust the the rpm to keep the engine operating on its optimum fuel consumption curve.

However, as you have already discovered there are precious few DC gensets available off the shelf. The PolarDC marine look good though. The engine is a volvo penta - so there should be no issues for spares/maintenance for that bit.

If you go for an AC generator, do not oversize it. I.e. ensure that during your battery charging you can load it to 75% of rated capacity. At only 50% load you AH will cost almost double in fuel. Only 15% load is very expensive in terms of fuel/AH and is not good for the engine.

Whatever you do, it is worth going for a 3 cylinder engine if possible. The reduced vibration will be appreciated.
 
wofforduk said:
doubt your batteries will last too long if you take them to 80% too often! but thats your choice :)

in any case, if you try to charge a battery, lets say a normal 110ah open lead, it will only take in a set amount of juice, even at a boosted voltage. so yes you will probably get 15a going into the battery for a short period of time (over the 10% guideline) however you could connect that up to a 1,000 amp alternator but it would still only take a charge of 15a
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Yup my deliberate choice as explained above. My objective is silent anchoring, not stretching the life of my batteries to the max

You can get waaaay more than 15A into a 110Ah battery, in the early part of the charge cycle ("bulk" or whatever it is called)That's just a fact, and I've owned at least a dozen mastervolt intelligent chargers in recent years and seen this on the displays. When you get to say 70% charge , the charge amps that the battery will take are much lower of course, but for the initial bulk charge 15/115 is waaaay less than can be achieved. Your 10% guideline is just misleading (and I never heard it before)
 
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