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 Post subject: Alternator W50
PostPosted: 11 Aug 2021 21:33 
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Skipper

Joined: 25 Apr 2016 10:25
Posts: 176
I have a Westerbeke W50 and the motorola alternator has given up the ghost. I am looking for a replacement and thinking about going slightly larger. Maybe a 90A or a 105A from Leece Neville or potentially a balmar. I would also plan on getting an external regulator as well.

Current battery bank is 470aH golf cart FLA batteries.

Existing alternator is Motorola MA12N600 which is a 51A externally regulated alternator. Does anyone have recommendations for which model number I should replace this with?

I'm going back and forth on whether the 90A is a good fit since It sounds like I would need to detune it with an external regulator since a 3/8 V belt can drive about 70-75A.


 
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 Post subject: Re: Alternator W50
PostPosted: 15 Aug 2021 06:09 
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Tactictian

Joined: 06 Aug 2020 09:02
Posts: 124
I went through the same issue recently. The problem is the W50 uses a 3/8" belt and that significantly limits your options. I ended up going with a Compass Marine 105A alternator and Balmar MC-614 regulator. My bank is three G31 Odyssey Extreme AGM 105AH. I set my regulator belt manager to 2 and I can charge at over 85A. Belt seems happy but make sure you align and tension correctly. I also installed a Sterling alternator protection device and service disconnect switch per Compass Marine directions.


 
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 Post subject: Re: Alternator W50
PostPosted: 16 Aug 2021 14:55 
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Skipper

Joined: 29 Dec 2006 09:38
Posts: 636
I ran a 105 Amp alternator on the 3/8" belt off my W50 for 15 years that included two years in the tropics with my Adler Barbour ancient, but very trusty, refrigeration. No problem. I have 440 Ah in two banks of flooded golf cart batteries. Never an issue with the belt, but I never ran the batteries flat and charged daily: generally about 120 ah in. If you really monitor the output of larger alternators with smart regulators and anything but the newest battery technology, the limiting factor for output is not the size of any component but the "acceptance rate" of your batteries and the temperature of the alternator's environment. Both of these mean that even your 50 amp isn't going to be putting out full power for very long or putting much stress on the engine or belt. I could hear the engine slow slightly when it kicked in. Very slightly. I can elaborate if you have questions, but there are graphs on the internet that can help demonstrate how output falls with heat and how acceptance rates (particularly with smart regulators) can taper the final stage of charge so much that your alternator rarely works near full capacity and buying a larger one is not necessarily going to boost outputs as much as you might imagine. FWIW.
I think I have a spare 50 amp that I carried for backup if anyone wants it. Free just pay shipping from California. Worked fine when I took it out.


 
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 Post subject: Re: Alternator W50
PostPosted: 20 Feb 2022 11:27 
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Able Bodied Seaman

Joined: 24 Feb 2014 00:12
Posts: 48
I love this site.

After several years of hand ringing I just bought a Balmar XT 170A alternator with external regulator and a K6 serpentine belt kit. This is how I arrived at the decision.

My current alternator is the OEM 55 AMP/hr that has the internal regulator.
My current bank is a tired 300 AH AGM that I have not been charging with the correct charging profile.

I eventually want to go with a lithium house and AGM starting battery.
The acceptance rate for AGM's to my understanding is greater than lithium that have a BMS that protects against too much input charge. so the 300 AH AGMs can take 0.5 C or roughly 150 amp at least initially in the bulk charge phase while a lithium is closer to 0.3C. I like the Balmar XT series because the amp input is so much higher under low RPMs. After a day of sailing I want to put as much into the bank as possible motoring into a anchorage for a 1/2 hour.

When I do increase the battery bank size I will have a strong alternator to supply current. 170A alternator is not that large when compared to some higher performance setups that are using 250 + amps. from my understanding the largest two consideration when going with a larger alternator are the energy draw from the engine and how to get the amp into the batteries.

I could have this all wrong and this is only my approach based on the research I have done for my specific needs and long-term sailing plans.

S/V Erewhon


 
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 Post subject: Re: Alternator W50
PostPosted: 20 Feb 2022 17:49 
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Skipper

Joined: 09 Aug 2017 15:35
Posts: 639
Location: Maine/USVI
I'm guessing you've got a W40 or other, since I can't find a serpentine belt kit anywhere for the W50 unless Balmar heard my pleas last year.


 
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 Post subject: Re: Alternator W50
PostPosted: 24 Feb 2022 11:12 
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Skipper

Joined: 29 Dec 2006 09:38
Posts: 636
One of the things folks seem to miss is the math of acceptance rate of your batteries. Putting a big alternator in your system is sort of like getting a fire hose (over a garden hose) to fill a wine bottle--with a dry sponge it--to 100% capacity. It will not matter how big your alternator is, if your batteries will only accept a fraction of that amp output after a short burst-- or if your batteries heat up from the process--something influenced much by the amount of amperage of the alternator itself. With a smart regulator with temp sensors on the batteries or on the alternator (or both) my guess is that most folks are not going to shorten getting to 100% by much by putting a huge alternator in their system. If you have Lithium Ion batteries with huge acceptance rates, it might speed things up a bit, but I really do not think most folks are actually doing the math and in touch with reality of the systems they construct. Nigel Calder actually prefaces this issue in his Boatowner Maintenance book and then goes delving (as he usually does) into the details and minutiae of adding every type of electrical "upgrade". What I have learned --the hard way--is to be thoughtful about my actual usage so that I do not spend my lifetime installing an maintaining complex systems that actually add little capability to my sailing life. My point is: do that math on the system capabiity. Acceptance rate is the key. FWIW.


 
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 Post subject: Re: Alternator W50
PostPosted: 26 Feb 2022 09:43 
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Able Bodied Seaman

Joined: 24 Feb 2014 00:12
Posts: 48
Update on my ultimate alternator upgrade.

I too learned that Balmar does not offer the k6 pulley kit for the Universal 5432 (M40). Dale at Balmar said they are just not getting enough order to make a run on the pulleys. So back to square one. This brings up a larger question. If we plan to sail our Tartans into he sunset of our lives do you repower before the engine starts to fail or run her out to the end. According to Dale parts for these old Universals will be hard to fined. Others on this site have done repowers. At my age I still have the energy to do a repower but will not be happy if something breaks on the hook in my retirement and I can't get parts for the the old gal. Oceanvolt, Yanmar, or Beta??....hmmm.

None of this seems important with what those folk are going through in Ukraine and Putin just pushed us into another cold war or worse. Very sad.


 
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 Post subject: Re: Alternator W50
PostPosted: 27 Feb 2022 11:44 
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Skipper

Joined: 09 Aug 2017 15:35
Posts: 639
Location: Maine/USVI
Yes, I think most of us, if running on the original, have a W-50. I've managed to find a lot of parts for mine and decided to make the best of it. Beta was close until the sales guy tried and tried to convince me the 25hp was enough "all you need" and I got leery.

And I bought a spanky new Reman Cummins instead. Since it wouldn't shoehorn into the Tartan I put it in the Dyer 29.

If I had to repower I'd probably go Beta simply for parts cost and availability (Kubota). 35 or 38, leaning toward the 35 as I recall.


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Engine Installed in Maine, then shipped to Caribbean to finish.jpg
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 Post subject: Re: Alternator W50
PostPosted: 28 Feb 2022 16:28 
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Skipper

Joined: 25 Apr 2016 10:25
Posts: 176
You can find pretty much any part you need for the W50 if you look at Calcutt Boats out of the UK. Much cheaper than purchasing through Westerbeke. The W50 is based on the BMC 1.8 which is used in canal boats in Europe.

With regards to the alternator pulley setup, I haven't been able to find anything that would let you run a larger belt. We are limited to the 3/8 belt which can only put out about 3hp so is limited to about 70A of output. You could get a 105A alternator and use the belt manager to run it at 70A and you shouldn't have problems with overheating.

I agree with the above regarding charge acceptance rates. The alternator only puts out what the batteries will accept which in the case of lead acid decreases as they continue to charge. So you may have some difference at the beginning of the charge cycle, but towards the end it won't matter. I have found it hasn't made a huge difference using a 50A alternator to get the batteries charged because things taper off fairly quickly.


 
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 Post subject: Re: Alternator W50
PostPosted: 02 Mar 2022 20:01 
Offline
Skipper

Joined: 29 Dec 2006 09:38
Posts: 636
Erewhon wrote:
Update on my ultimate alternator upgrade.

I too learned that Balmar does not offer the k6 pulley kit for the Universal 5432 (M40). Dale at Balmar said they are just not getting enough order to make a run on the pulleys. So back to square one. This brings up a larger question. If we plan to sail our Tartans into he sunset of our lives do you repower before the engine starts to fail or run her out to the end. According to Dale parts for these old Universals will be hard to fined. Others on this site have done repowers. At my age I still have the energy to do a repower but will not be happy if something breaks on the hook in my retirement and I can't get parts for the the old gal. Oceanvolt, Yanmar, or Beta??....hmmm.

None of this seems important with what those folk are going through in Ukraine and Putin just pushed us into another cold war or worse. Very sad.

I share your angst about war and talking about our yachts as the world ignores the fact that that UN scientists just announced that the window on providing our grandkids with a "liveable" world due to climate change is closing. But here I go:
I faced the same issues you are: I was about to take off on a 7,500 mile trip from San Francisco down and up Central America to Maine with my T37 and had a leaky W50 that I knew quite well and had a lot of replacement parts. I decided to stay with it for the trip because I did not want to learn a new engine on the trip and that worked out well: The engine added about 1000 hours without any major issue. I then faced the issue when I got to Maine about whether this was the engine I wanted to baby for the rest of my life. I went with Yanmar 39 HP 3JH model because that is what I saw most folks out cruising did. The engine swap required a revision of the engine bed which I was glad I did not do before heading out in the wild. Getting all the new stuff running right took some time. Anyone who says they have a "drop in replacement" is lying to you. There is no real customer service support with Yanmar, but I think the engines are generally better build specifically for marine use--the major problems with marine diesels is usually in the "marinization parts" not in the engines themselves. Yanmar pays attention to this. Beta folks seem to generally rave about the support they get, but the engines seem to have the usual issues of an adapted engine over time (dissimilar metals in the raw cooling systems is the big one). So my advice is that if you know the engine and have a modicum of confidence in it--stay with it. Running for hours is not going to stress a diesel nearly as much as simply running the same amount of hours in and out of a slip or on weekend jaunts. I carried spares of the W50 fresh and raw water pumps and a spare alternator. I had to use the fresh pump in a tight situation, but my experience with replacing it made it easy. So experience counts. I have 1000 hours on my Yanmar and have only changed the oil. Inspected the elbow and it was clean as a whistle. That is my advertisement for Yanmar. But they are the shits for customer service.
Ray Durkee


 
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