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Old 27-03-2007, 17:14   #1
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two alternators or one ?

I am having a bit of a problem obtaining a 180 amp alternator here in Ausralia at a decent price.

I will be using a 13 hp Honda engine which I intend to connect to a 180amp alternator.
Should I consider two 90 amp alternators (cheap) instead of the one 180 amp.
Are there any problems doing this.
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Old 27-03-2007, 17:56   #2
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Why do you want a 180 amp alternator? You would need a humongous battery bank to have an acceptance rate that could efficiently take current from such a large alternator.

On my ninety amp alternators with three stage regulation, the maxiumum power output only lasts for about fifteen minutes before the output is reduced to what the batteries can safely accept.

I am on a catamaran, and I never ran both engines at the same time to charge my batteries. Their combined output was potentially 180 amps with both of them running, but running them both never made any sense to charge my four deep cycle batteries. I found that solar power and wind generators put out levels of current that my batteries could accept.

I used four solar panels and two aerogen 6 wind generators when I was cruising in Australia, and they did an excellent job of keeping my batteries charged with occasional help from one of my alternators.

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Old 27-03-2007, 18:00   #3
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I think you might want to map out a little more details for us. The idea of a 180 amp alternator on a 13 HP engine just seems too strange to understand. Nothing wrong with strange just the bigger picture of this has me very curious. I think you could get better feedback if you explained.
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Old 27-03-2007, 18:11   #4
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Quote:
Originally Posted by maxingout
Why do you want a 180 amp alternator? You would need a humongous battery bank to have an acceptance rate that could efficiently take current from such a large alternator.
I might venture to guess Beau looking to build an efficient DC genset of sorts. I have a similar setup, charging only 4 Trojan T-105's, or a 440AH bank. I have twin 90 amp smart chargers, equaling the same output as his twin alternators would. The reason you want max power flowing into the batteries is to conserve on gasoline (or diesel in my case). The whole setup is of the type that charges your batts at max acceptance without running the main engine. Very economical and efficient.

Beau: I think if you have no issues with wiring and/or setting up the belts for two alternators on your system, why not? At least this way it would cost less and also allow you to have power if one of the alternators fails. Additionally, if you were to carry a spare alternator, you could easily swap an inexpensive 90 amp into your system if one of the two failed.
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Old 27-03-2007, 18:27   #5
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Thanks ssullivan.

I am building a power trimaran based on two 30 hp outboards. however they only put out 15 amp each when underway.

I am putting in 800 amp hours of AGM batteries which charge at a much higher rate than wet cell.
I am planning to use all 240volt appliances (mains current in Australia) with a 2500amp inverter. A 9,000btu airconditioner will be used at night. which is far far cheaper than 12 volt systems and I am happy to replace them all in two - three years. I save $10,000 by using this system.

I dont believe solar or wind is very efficent if you take into account the extremely high capital cost and variability of use. $3,000 of capital cost goes a long way with running a Honda at 1/2 gallon of gasoline per hour.

I plan to have a 13 hp Honda auxillary but I don't want that running all day either. So the more I can pump out of the alternators the better, even if it is only up to 80-90 % of battery capacity (smart charger)
The honda will also run a Cat high pressure pump for desalination.

I do like the idea of having two alternators which I can buy (new) for $150.00 each whereas a 180 amp would cost be over $1,000.00.

A 13hp can easily run two 100amp alternators.
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Old 30-03-2007, 06:20   #6
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I have had multiple 90 amp alternators from Balmar on my 28 horsepower yanmars. Each yanmar has 4000 hours on it and so the alternators have plenty of usage.

Twice, the alternator feet have fractured off from the frame of the alternator. Both times the feet were welded back in position. If you would like to see where the typical fractures occur, and a repair of the fractured alternator foot, you can see it at the following video.

Go to: dvd and click on Episode Three where you will see the damaged alternator and the repair process in a yemeni machine shop.

Cheers,
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Old 30-03-2007, 11:08   #7
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Those with Balmar alterantors, How many hours do you get between rebuilds? I have a new 70-110 on board and am wondering if I should get spares kit for it or just keep the old Yanmar unit to drive the pump with if the Balmar goes and replace it at the next convenient stop. Any thoughts?

Peter
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Old 30-03-2007, 11:32   #8
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Quote:
Originally Posted by Songline
Those with Balmar alterantors, How many hours do you get between rebuilds? I have a new 70-110 on board and am wondering if I should get spares kit for it or just keep the old Yanmar unit to drive the pump with if the Balmar goes and replace it at the next convenient stop. Any thoughts?

Peter
I have used balmars for more than ten years, and I have never had to rebuild them. I just had to have the feet welded back when the feet fractured. The holes in the feet sometimes enlarged over time as well. I have never had to replace the alternators because of failure of the internals or the diodes. I don't carry rebuild kits because I have never needed one. Each engine has over 4000 hours of running time, and my balmars keep on ticking.

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