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Adapting OEM 50A alternator for external regulation

peaman

Sustaining Member
I have reviewed lots of discussion about upgrading alternators and mounting brackets, in preparation for installing an external regulator. Wishing to not go overboard, I am considering adding the regulator to my 2 year-old OEM Westerbeke 50A alternator, part # 41017. Attached image is a (poor) rear view of the alternator, which is different from any alternators I have seen in YouTube videos showing conversion wiring.

I wonder if adaptation of my alternator a suitable DIY project, or will I need to take it to a shop for that? I'm a decent mechanic, and I understand the electrics involved, but I wouldn't want to make a costly mistake in wiring this thing.
 

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Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
Maine Sail (R.C. Collins) has written a good deal on this complex topic. Take at look on this link at "External Regulator Conversion" among others.

(Collins is incapacitated by a massive stroke and many of us have sent support in thanks for his help over the years)

 

peaman

Sustaining Member
I have reviewed lots of discussion about upgrading alternators and mounting brackets, in preparation for installing an external regulator. Wishing to not go overboard, I am considering adding the regulator to my 2 year-old OEM Westerbeke 50A alternator, part # 41017.
Of course, Marine How To was one of the sources I reviewed, but while the site describes in great detail why external regulation is useful, and potential problems to be aware of in installing a larger alternator, it does not have much good to say about OEM alternators, let alone anything about adapting one to external regulation.
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
I thought the Leece-Neville is more or less the same as our stock Motorolas, no? He describes conversion for addition of external regulator.

I have no idea if it's worth it.
 

peaman

Sustaining Member
I thought the Leece-Neville is more or less the same as our stock Motorolas, no?
The Leece-Neville shown has a factory installed regulator which is bolted onto the back of the alternator. The site once offered a "dummy" replacement for that regulator, with needed terminals, to facilitate connection to an external regulator. The link to the "dummy" cover now results in a 404 file not found error.

Apparently, conversion can be accomplished if 4 specific terminal points can be connected-to: Battery, ground, and two field terminals. So the hard parts should be 1) identifying each terminal point, 2) removing any unnecessary parts, like the internal regulator, and 3) connecting to the external regulator in a "proper" manner. In particular, Maine Sail calls out a spark arrestor gasket which seals around the brushes enclosure on the conversion package that was once available. So there could be some serious barriers to conversion.

The rear of my own OEM alternator looks very different from the Leece-Neville image, so I guess I will need to remove it for closer examination.

EDIT: based on images, my OEM alternator might be a Volvo Penta unit similar to model 3860171, which may well have a regulator similar to the Leece-Neville, even though the image of the L/N looks nothing like mine.
 
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sailing42

Member II
I am not sure which system you are dealing with but I fitted a Sterling Pro Reg D external regulator to my Hitachi alternator. To do this I had to remove the alternator, split the case and remove the rotor/shaft to expose the two brushes. The Sterling ties into the brush lead so I had to expose part of the wire to the brush and solder a pigtail of wire which had to be routed out of the case. These are the field terminals and as they are added to the existing connections if there is a problem with the Sterling unit then the alternator will continue working normally. I would not be comfortable fitting a unit that takes the existing regulator out of the circuit.
The Sterling regulator also ramps up the charge rate to prevent belt slippage but I upgraded my stock V belt to a ribbed Gates V belt. Before removing your alternator take a bunch of pictures of the rear of the alternator so you can figure out how you will install the upgraded wiring ( heavier gauge positive and ground wires ) to handle the increased current. It's quite a project but you should be able to figure it out.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
The maker has quite a spiel, but then I would expect that. Price average around some 'net sites seems to run around $175. If hired out, the install labor cost would be equal or twice that in my experience. If spending more vacation time aboard this sounds like a good option. I wonder how this integrates into a storage system like mine, with a twin six volt GC flooded house bank and a spiral cell AGM 12 volt battery reserved for emergencies?
Thanks for information and the details.
 

sailing42

Member II
Loren, not sure how your batteries are set up but if you are looking at external regulation then I think your house bank would be tied into the system and the spiral cell perhaps hooked up to a solar panel to keep it charged. If I understand you correctly you have two sets of 6-volt batteries so you would have an automatic charging relay connected to the house bank. I do not think there is any way to include the spiral cell AGM as it would require a different charging profile. One other thought - your house bank would appear to be close to 1000 Amp so I'm wondering if external regulation with a stock alternator would work, but that depends on how many Amps you consume/would have to replace. If your electrical consumption on the hook is moderate - LED lighting etc then the load/demand put on the stock alternator with external regulation is not too great and it should work fine as long as you have temperature sensors on the alternator and batteries and a way to keep track of your state of charge. If you have a pretty good load then you would have to look at upgrading belts/pulleys and alternator as well as the external regulator. This is my understanding of this subject but perhaps I'm getting sidetracked on this. I did my conversion a few years ago and it has worked fine so far, on average after a night or two on the hook I end up with an initial charge rate of just under 40 Amps and this drops pretty quickly (bulk charge). one last comment: as with most boat-related projects the costs climb pretty quick - you need to upgrade the wiring, current protection and improve the ventilation to the engine compartment so the alternator gets some fresh air.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
To clarify, our batteries are the Trojan T-145+, and the two-battery bank is 20-hour-rated at 260 AH. All of our lighting is LED and our refrigeration is quite efficient. We usually go for two full days on the hook and have ample power to start the diesel. At that point we will show about 12.3 or 12.4 VDC on the meter.

I do sometimes wish that the charging sources could feed voltage separately into the AGM emergency battery as well as the house bank, but this scheme has been working for over 20 years, for us. I suspect that the saving grace is that the desired/desired charge voltage is very close between the two battery chemistries.
Perhaps we just have happy ignorance powering our bliss. :)
Disclaimer: our solutions are seldom the 'best', even when they work for us.
 
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Pete the Cat

Member III
I thought the Leece-Neville is more or less the same as our stock Motorolas, no? He describes conversion for addition of external regulator.

I have no idea if it's worth it.
I think if you read Maine Sail and Nigel Calder carefully, they both suggest at the beginning of their "how to" sections that, for most folks, the cost and work inolved is not going to be justified by better performance or longer lasting batteries--they only give this point a sentence or two because they go right into the how to process. I have made the conversion and I would not do it again. Frankly, the "smart chargers" are wonderful if you are motoring for days on end and regularly dropping your batteries to 50% in a cycle--they will be very kind as they bring your batteries back if you are patient about how long it will take to get them topped off. But they also have a very slow top off rate that can leave batteries used for shorter periods in a state of chronic undercharge--unless you use solar or shore power to top off where the charge cycle leaves you after an hour or two of engine time.
I believe Leece Neville made most of the Motorola alternators--and many others. Up to a couple years ago they made most of the Balmars as well. The main difference between a truck alternator and a marine alternator is often just the seal on the regulator: the USCG requires even alternator regulators used in diesel applications to be spark resistant to be certified for marine use. When you crack them open, the the bearings and windings all look the same.
 
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