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Old 20-03-2012, 12:50   #16
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Re: Water cooled, high amp 12v alternator

add #14. Its not the belt nor the pulleys, but the bearings of the engines standard waterpump that are not designed for, and cannot withstand this axial load.

add #15. I a car the alternator almost never charges at max. output for more then a few minutes, with the used automotive regulators simply not possible.

When a generator is used with an external regulator it is forced to produce maximum output, in my case 200A for up to 2 hours to charge my 800 Ah bank. This will bring the alternator, by experience, to temperatures above 98 degrees. This they not like :-)
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Old 20-03-2012, 13:21   #17
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Re: Water cooled, high amp 12v alternator

DC Generator - The Smart Way to Go

This was how I over came the side loading problem , and the "LoveJoy" connection has a soft urethane spider in it that helps absorb any vibration. I figure it takes about 9 hp to turn my alternator.

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Old 20-03-2012, 14:07   #18
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Re: Water cooled, high amp 12v alternator

capn_bill (#14)

It is generally accepted that, due to inefficiencies, it will take 4hp to drive a 100A 12VDC alternator. Thus, a 200A 12VDC alternator will take at least 8hp and will require either a dual 1/2" vee belt or a serpentine belt to drive it.

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Old 18-04-2012, 17:06   #19
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Re: Water cooled, high amp 12v alternator

CeesH,
I tend to agree with Capn Bill. Why are you of the opinion that a nominal 200A output alternator will destroy your water pump bearings if used in the factory position?
I have seen this statement before and would like to qualify it if possible.
Can you cite your source for this? A Yanmar or Westerbeke spec document perhaps?
I note Yanmar offers up to 80A factory alternators these days. Which if you use 25A/12V = 1Hp, the water pump load is 3.2 HP nominal. You'd be at about 8 HP nominal with your 200A.
Does the difference between 3.2 and 8 HP exceed someone's water pump bearing spec? And remember once the batteries approach their absorption set point that load is gone. Which ought to take less than an hour with that much alternator output for say a 800Ah bank.
Furthermore, with serpentine belts there is supposed to be less tension required.
Thanks.
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Old 19-04-2012, 09:43   #20
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Re: Water cooled, high amp 12v alternator

From my experience, trying to use a single V belt to drive a 100 amp alternator, (with a regulator that drives them hard) You have to tension the belt quite tight compared with a smaller output alternator. Even then I would have belt squealing issues at start up with a soft start regulator. Black dust accumulated in the engine room and retensioning was necessary often. I often worried about the side loads with these setups (3 diff boats, two with yanmars , one with perkins) However, I never did actually have a failure, but I would expect that it would happen eventually. A serpentine belt would be a nice way to go for sure...
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Old 19-04-2012, 10:49   #21
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Re: Water cooled, high amp 12v alternator

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Originally Posted by Cheechako View Post
From my experience, trying to use a single V belt to drive a 100 amp alternator, (with a regulator that drives them hard) You have to tension the belt quite tight compared with a smaller output alternator. Even then I would have belt squealing issues at start up with a soft start regulator. Black dust accumulated in the engine room and retensioning was necessary often. I often worried about the side loads with these setups (3 diff boats, two with yanmars , one with perkins) However, I never did actually have a failure, but I would expect that it would happen eventually. A serpentine belt would be a nice way to go for sure...
I have a Balmar 125 amp alternator on my y3m30 Yanmar-with only 1 belt with the smart regulator ,never had troble-1300+ hours - it was made for 2 belts but works great with one
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Old 19-04-2012, 11:20   #22
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Re: Water cooled, high amp 12v alternator

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I have a Balmar 125 amp alternator on my y3m30 Yanmar-with only 1 belt with the smart regulator ,never had troble-1300+ hours - it was made for 2 belts but works great with one
Interesting.... 2 of mine were on 3GM30 yanmars. I'll bet you're using a balmar regulator....? I had a Balmar and also Ample Power regulator on 100 amp AP alternators. The Balmar reg put out 15 less amps initially than the AP reg. ont he same setup. Maybe that's why?
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Old 20-04-2012, 22:40   #23
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Re: Water cooled, high amp 12v alternator

Look under the hood of a new car and you’ll find idler pulleys one of them being an automatic belt tension or the others primary job is to reroute the belt so that you get more pulley surface. The alternator on my diesel truck has almost 50% health coverage where as a lot of alternator pulley’s specially V belt alternators. Just my two cents, Mike.
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Old 21-04-2012, 07:26   #24
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Re: Water cooled, high amp 12v alternator

For warm climates, I'm convinced that an external voltage regulator mounted away from the hot engine will solve a lot of alternator failures. The voltage regulator is vulnerable to heat, and it being mounted inside of the alternator case is about the worst place for a heat sensitive electronic circuit. Forced ventilation in the engine compartment can lower the the engine intake air 20 degrees depending on the outside air temp. Putting a $15 (Walmart/Radio Shack) remote sensor thermometer in your engine compartment will tell you if your engine room is too hot. The batteries, engine, hoses, wiring, etc. don't like temps probably above 100 degrees F. Many boat alternators are not designed for marine use, and are for cars with 50 mph outside air cooling them. Boat engine compartments usually have zero air flow, just the little alternator fan blowing warm air, trying to cool the case and regulator, causing premature failure. Has anyone had better luck with some of the marine external voltage regulators?
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Old 21-04-2012, 10:54   #25
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Re: Water cooled, high amp 12v alternator

Look under the hood of a new car and you’ll find idler pulleys one of them being an automatic belt tension or the others primary job is to reroute the belt so that you get more pulley surface. The alternator on my diesel truck has almost 50% health coverage where as a lot of alternator pulley’s specially V belt alternators. Just my two cents, Mike.

Yeah, contact area on the pulley would be a big improvement. I think the average contact of the V belt is maybe what....35%? I wish my truck had health coverage.... maybe it would be better than mine!. :>)

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For warm climates, I'm convinced that an external voltage regulator mounted away from the hot engine will solve a lot of alternator failures. The voltage regulator is vulnerable to heat, and it being mounted inside of the alternator case is about the worst place for a heat sensitive electronic circuit. Forced ventilation in the engine compartment can lower the the engine intake air 20 degrees depending on the outside air temp. Putting a $15 (Walmart/Radio Shack) remote sensor thermometer in your engine compartment will tell you if your engine room is too hot. The batteries, engine, hoses, wiring, etc. don't like temps probably above 100 degrees F. Many boat alternators are not designed for marine use, and are for cars with 50 mph outside air cooling them. Boat engine compartments usually have zero air flow, just the little alternator fan blowing warm air, trying to cool the case and regulator, causing premature failure. Has anyone had better luck with some of the marine external voltage regulators?
It is amazing how hot a big alternator gets when asked to put out a 100 amps for a few minutes. OTOH.... I've never had an actual failure.... I have had a couple rebuilt before going on a cruise etc. I'm not sure there is a big failure rate on alternators... anyone else have that issue? A water cooled one might put out more amps for longer though...?
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Old 21-04-2012, 11:04   #26
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Re: Water cooled, high amp 12v alternator

"Try taking the temperature of the space after running the engine for an hour - get a sense for what the 'real' temp is."

I've done this with several boats using a cheap remote sensing thermometer. We solved a lot of long term problems by lowering the eng rm temp by 20 degrees. The eng, batteries, alternator, and wood appreciate the cooler temp. The $15 thermometer has additional advantages. It's worth havng one permanently mounted near the nav table.
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Old 22-11-2017, 03:31   #27
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Re: Water cooled, high amp 12v alternator

Even if this thread is 5 years old, alternator heat problems are still a big problem as can be seen in several threads on this topic.

Still noone that tried using a water-cooled alternator on a boat? They are expensive, but i just found out that they can be bought used quite cheap, 14V 150-200Amps for about 150€.
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Old 22-11-2017, 04:10   #28
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Re: Water cooled, high amp 12v alternator

Are you suggesting cooling with salt water? that brings its own problems with salt build up and corrosion does it?
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Old 22-11-2017, 06:50   #29
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Re: Water cooled, high amp 12v alternator

That just seems like a lot of work and complication when you can have $1,000 Honda generator and run a 35 gallon per hour water maker and charge the batteries with 65 to 70 amps DC and put no hours or stress on your engine
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Old 22-11-2017, 07:28   #30
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Re: Water cooled, high amp 12v alternator

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That just seems like a lot of work and complication when you can have $1,000 Honda generator and run a 35 gallon per hour water maker and charge the batteries with 65 to 70 amps DC and put no hours or stress on your engine
Ain't that the truth.

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