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Discussion Starter #1
I have a Westerbeke 30, 4-91 British Leyland block. I am looking for a replacement regulator for my original Motorola M12N51 alternator. I took the regulator off and could not read the numbers. I have the original wiring schematic, and i took #11550 for the regulator off of it. When searching the web I came up with Torrenson Westerbeke #11550 for 75$......
Or.....
Ebay:
Alternator Regulator Motorola Prestolite 12N A 8AL Ha MA | eBay
I have no experience with these. Is there a marine and non-marine application, and does it affect my purchase choice?
Also..does this marine application require the regulator housing to be
grounded?
Or.....any ideas on another source? Perhaps a source that also sells parts for the Motorola if I decide to go through it again?
Thanks!
 

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Santa :

Marine and automotive applications are the same. Just keep the regulator dry and you will be OK.
The regulator will almost certainly have an earth wire included with it and it needs to be grounded.
The regulator compares the output voltage from the alternator's rectifier (rectifying the alternator's AC to DC) to a set internal voltage (typically about 14.2 V, or so), and if it is too low, the regulator routes some more current to the spinning rotor of the alternator via the alternator brushes, so strengthening the magnetic field of the rotor and recovering the voltage. If the voltage rises too high, the regulator reduces the current to the rotor again. It is a switching arrangement within a wee solid state controller, and it is constantly switching back and forth at high speed.
Most alternators have the rectifier built in to them.
Some alternators have the regulator built in to them also.
Your regulator is an external unit.
The regulator should have some basic instructions with it telling you how to wire it to the alternator. I would not want to guess. They really must tell you with the instructions.

Rockter.
 

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Discussion Starter #3
The old one was open on one side.....and filled with crumbling old foam? I do not remember my auto regulators to be this way? Yes there is a ground that splices to the Alt. gnd. I seem to remember a legit mechanic telling me to make sure the body of the regulator makes good clean contact to the car.....so I ran a gnd. to an unpainted corner of this regulator.
I have 0 output....I respliced all connectors.....still 0.....so I am questioning a few things. I was going to start with replacing the regulator. If that doesn't get flow, I will pull the Alt. off and get it bench tested.
The splicing is straight ahead....color to color. If the regs are all the same...then I am going to pick up two for the price of one off Ebay.
Thanks for your help.
 

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santa...
Run a makeshift positive wire from your battery, and with the engine running and your hands clear, MOMENTARILY touch the battery positive to the field wire of the alternator at the alternator end (of course). You should hear a change in the belt whine as the load comes on to the alternator field and so to the alternator drive belt.
If you hear the whine, then I reckon the alternator is doing OK.
Don't hold the wire there for too long as the alternator will be likely to overheat and don't short the wire to the engine block or things will get hot in that wire pretty quickly.
With the makeshift (unregulated) feed to the alternator field wire, the alternator will be at full load so pull the field wire connection clear promptly if and when you hear the belt whine.
Wear goggles and keep your face and hands clear of the plane of the belt. There is a heck of a load on the alternator drive belt at unregulated full load and the belt may decide to part at that moment.
Let us know how you get on.
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Discussion Starter #5
Small spark....no apparent loading. Meter was at 12.9, with solar slightly charging.
No change in RPMs.
 

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Santa...
Looks like you may have shed a brush in the alternator or lost continuity to the rotor. You are not energising the rotor. Can you open up the alternator and have a wee look?
It may be easy to fix.
It happened to me once and it was obvious. I just put a new brush in there.
You may have lost continuity in the rotor. Again, a multimeter placed across the brush tracks should betray the problem. Loss of continuity in the rotor will mean a rotor re-wind or new rotor I reckon.

Rockter.
 

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santa...

Your planned alternator looks like a good one, with a 90 A rating. I wonder what its continuous rating is though?

If you budget extends that far, I can recommend the small frame alternator from Ample Power. I fitted one in 1992, and it is still working fine. It did shed a brush once, but I fixed it easily. They are not cheap at close to 500 bucks, but that hot running specification is quite something, with 100 A continuous at ambient air close to 90 C. I can't imagine an engine room getting that hot, but anyway....

Ample Power Alternators

.... so they should have no trouble handling a typical charging load of, perhaps, 30 A.
As a rule, I charge often, and so don't have to load the alternator heavily. It helps extend the belt life too. Hard charging does not do much for belt life, nor for your batteries.

I did have a spare alternator on board, and when the Ample Power alternator shed a brush, I fitted the spare alternator. It was a 100A rating from a reputable supplier. I shan't name them, but I can tell you that the spare alternator did not last a single afternoon... one of the stator coils just fried (far too hot to touch the alternator housing and with no output) and it only pulled about 30A before it did fry. I had to pull in to a wee Scottish harbour and find someone with a soldering iron to fit a new alternator brush to the Ample alternator. Maybe I just got unlucky with the spare alternator. Anyway, you live and learn.

I guess it is a question of trust.

I have no vested interest in Ample Power. I just like their alternator and 3-step regulator, and 22 years later, they are still working and they put out a good output without complaint.

Rockter.
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Thanks Rockter!

Sounds like a plan.

I am looking to place a Leece-Neville 8MR for a primary, and fix the Motorola. I am looking for an affordable source, as ASE:

Leece Neville*110-603 - 12V 90 amp ALTERNATOR

would not deliver to my PO box.

I appreciate the help, and the tip on bypassing the reg.
Good stuff!
Have it delivered to your marina or a friends house.. ASE is an excellent company.. That alt can easily be converted to external regulation...
 

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santa...

Your planned alternator looks like a good one, with a 90 A rating. I wonder what its continuous rating is though?

If you budget extends that far, I can recommend the small frame alternator from Ample Power. I fitted one in 1992, and it is still working fine. It did shed a brush once, but I fixed it easily. They are not cheap at close to 500 bucks, but that hot running specification is quite something, with 100 A continuous at ambient air close to 90 C. I can't imagine an engine room getting that hot, but anyway....

Ample Power Alternators

.... so they should have no trouble handling a typical charging load of, perhaps, 30 A.
As a rule, I charge often, and so don't have to load the alternator heavily. It helps extend the belt life too. Hard charging does not do much for belt life, nor for your batteries.

I did have a spare alternator on board, and when the Ample Power alternator shed a brush, I fitted the spare alternator. It was a 100A rating from a reputable American supplier. I shan't name them, but I can tell you that the spare alternator did not last a single afternoon... one of the stator coils just fried (far too hot to touch the alternator housing and with no output) and it only pulled about 30A before it did fry. I had to pull in to a wee Scottish harbour and find someone with a soldering iron to fit a new alternator brush to the Ample alternator. Maybe I just got unlucky with the spare alternator. Anyway, you live and learn.

I guess it is a question of trust.

I have no vested interest in Ample Power. I just like their alternator and 3-step regulator, and 22 years later, they are still working and they put out a good output without complaint.

Rockter.
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The Ample Powers claims of superiority always amuse me..:) Especially since my own brand of alternator is built by the same small company, only to slightly better specs. Stators, rotors, bearings etc. are all identical.. Difference is I don't make outlandish claims such as "continuous output for as long as it takes". That is simply marketing BS and does not tell the whole story....

The Ample alts and my own brand are very good alts but they are not as good as some other small case alts. At one time they were the best built small case alts, but today we have many more options... Difference is I am honest about that with my customers.....;)

Does the one on the right look familiar..?


BTW the one on the left is slightly smaller case and will run circles around the one on the right. Both are great alts but one has better low RPM performance, better cooling and significantly higher output for longer.. Course you pay a lot more for the one on the left too.....;)

For the OP, with a typical flooded battery bank, the LN 90A would be fine..
 

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Maine sail :

I seem to have hot a wee nerve there, have I not?

Yes, the one on the right does look familiar.

I made no outlandish claims for the Ample Power alternator, nor did Ample. It keeps working.

They sold me an alternator that is still working 22 years after I fitted it and it is able to meet any load I have ever thrown at it. And it doesn't eat belts either!

My experience with a different and much better known marque would be laughable if it were funny. It lasted not even a single charge. I took it the whole way as a reserve from Houston to Scotland, and the first time I needed it, it fried. Zero output after about ten minutes, and man did it fry.

Things will have moved on more than a little in 22 years, and although I don't look forward to the day I may need another alternator, I will have more choice now than I did have then.

This looks like a good one too...

https://www.youtube.com/watch?v=Z0ijfk0DMPk

...though I would be less confident about keeping seawater out of those exposed windings as I would be with an Ample Power alternator. In my older boat, (a 1977 USC Polaris 36) a mid-Atlantic gale left seawater everywhere, and I mean everywhere... "water puddles on the cabin seats" sort of thing. It got in to the engine room too and on to the motor.

Still, 140 A in the video is serious output.

I might be tempted to get another small frame alternator from Ample Power though, as I am sure you will understand, and it will not need to run circles around the performance of the first one I bought from them. The same will do, although there will probably be more choice today than back then.

Best...

Rockter.
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Maine sail :

I seem to have hot a wee nerve there, have I not?

Yes, the one on the right does look familiar.

I made no outlandish claims for the Ample Power alternator, nor did Ample. It keeps working.

They sold me an alternator that is still working 22 years after I fitted it and it is able to meet any load I have ever thrown at it. And it doesn't eat belts either!

My experience with a different and much better known marque would be laughable if it were funny. It lasted not even a single charge. I took it the whole way as a reserve from Houston to Scotland, and the first time I needed it, it fried. Zero output after about ten minutes, and man did it fry.

Things will have moved on more than a little in 22 years, and although I don't look forward to the day I may need another alternator, I will have more choice now than I did have then.

This looks like a good one too...

https://www.youtube.com/watch?v=Z0ijfk0DMPk

...though I would be less confident about keeping seawater out of those exposed windings as I would be with an Ample Power alternator. In my older boat, (a 1977 USC Polaris 36) a mid-Atlantic gale left seawater everywhere, and I mean everywhere... "water puddles on the cabin seats" sort of thing. It got in to the engine room too and on to the motor.

Still, 140 A in the video is serious output.

I might be tempted to get another small frame alternator from Ample Power though, as I am sure you will understand, and it will not need to run circles around the performance of the first one I bought from them. The same will do, although there will probably be more choice today than back then.

Rockter.
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You didn't hit a nerve at all, and made no claims, but the link to Ample did.. I just always find it amusing how they market that alternator so vastly different than I do... I would never market my alt the way they do, with outlandish claims, but some companies love to chest thump. Truth is 98% of the time they can get away with it because most installations don't really tax the alt too badly or the temp compensation deals with it and the owner never knows.

That video is actually mine, it's an Electromaax 140A. With that engine room closed up tight I current limit that alt to about 115A with the Balmar reg. It has been feeding that bank of TPPL AGM's now for a few years without so much as a hiccup..

The dual fan CS130 based HO builds like Balmar, Grasser and E-Maax are building really do perform well and cool nicely. The hairpin alts Balmar is doing can't be beat for small case designs. They have insane outputs for the case size. You used to have to go to a full frame ambulance alternator to do what Balmar is now doing in a small case. They have really opened up options with lithium installations and small sailboat motors..

In full disclosure I am a dealer for Electromaax, Mark Grasser DC Solutions, Balmar and also build my own Compass Marine Alts which are the same as AP's. I sell more Balmar than just about anything else even though I make the least on it. They have come a long way and stand behind the product extremely well. They also have humans who answer phones. I like that. Mark Grasser's stuff is another main go to product for me and Mark answers the phone personally.

Still the AP alts are great alts for a medium duty application (meaning most sailboats). I would kill one with a LiFePO4 bank but my Mark Grasser 160A has been working like a beast for two years now and doing remarkably well despite the abuse that LiFePO4 bank gives it..

My only point is that today we have many more options than we did back in the 90's. Any well built HO alt correctly set up should last for 20+ years. Eventually you will need to do brushes and perhaps bearings but all else should be fine. I have many early 90's Ample's, Balmar's and Hehr Powerline's still going strong..
 

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Mainsail:

Thanks then.

What grease should I use for the AP bearings? It's a 1992 small frame. They are due a wee service this winter and it has been a while since I greased them.

Rockter.
 

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Mainsail:

Thanks then.

What grease should I use for the AP bearings? It's a 1992 small frame. They are due a wee service this winter and it has been a while since I greased them.

Rockter.
They are sealed bearings so no grease. You just replace them when they wear out. Any bearing shop can order you a good quality bearing replacement. A normal Delco 10DN bearing should not fit as the cases are built for slightly larger bearings, despite being based on the 10DN frame.. All you should need is brushes & bearings and an inspection of internal wiring. Unless you over heat it/cook it bearings and brushes are what wear out. You can also fry the diodes with an on/off switch but if that has not happened in 22 years it won't likely happen or perhaps you are direct wired to the bank, as any HO alternator should be...
 

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Discussion Starter #15
Any suggestions for an external regulator for the 8MR? I missed a Balmar 612 Ebay auction a few days ago. I don't need much....something budget like the Leece-Neville. I want to have a delayed loading.....and the derating of the Balmar is great.....but I am not sure that I need it.
Your help appreciated.
 
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