Most common alternator issues in the field

[belizesailor]

Originally Posted by wsmurdoch

We carry a complete spare alternator (never used in 14 years) ...

Sell it at the next swap meet...and you will need it soon! [emoji16]

[boatpoker]

Originally Posted by billknny

Very few people will carry a full set of diodes and regulator parts for their alternators. When an alternator craps out, most people take it to a rebuild shop. It is easy and inexpensive.

Unless it happens in the Bahamas .... 2 weeks and $650.

My spares did not help as their was too much damage when it fried. Now we carry a spare alternator.

[sailingharry]

Originally Posted by boatpoker

Unless it happens in the Bahamas .... 2 weeks and $650.

My spares did not help as their was too much damage when it fried. Now we carry a spare alternator.

A full spare can be pricey. Nice, but pricey. A full Balmar alternator/regulator spare is closer to $1K, a lot of money for "just in case, just to get home." A decent compromise is an internally regulated automotive alternator in the 50-100A range. Not ignition protected, but most of us have diesel engines. May burn out in a few months. May not be smart 3-stage regulation. These can be had in the $50 range, and give you a bolt-in field repair. Many are even "one-wire" configured, a philosophical disaster, but very simple and functional for "a get home" spare.



I've had good luck with 10SI, 12SI, and CS130 series GM units that fit nicely on my old Volvo MD11C. The CS130 is even fairly easy to convert to external regulation (with the internal regulator left installed as a backup).



Harry

[LargeMarge]

Originally Posted by wsmurdoch

We have broken alternator belts several times.

Bill

Why do you have broken belts? A set or two of new == unbroken == belts makes sense to me. What do you do with broken belts? Can you repair them? Are your broken belts good for spares? How long do your repaired belts function compared to new?

Please, post photographs of the repair process.

[sailingharry]

Marge,


I'm assuming your questions are sincere. Some thoughts:


* Marine belts drive the alternator, which is typically loaded MUCH more heavily than an automotive alternator. This results in slipping, and wear, and stress, which can break the belt (or at least, wear it to the point that a prudent operator replaces it). Boats often load a single V-belt to the limit of safe operation -- cars are using serpentine belts with much higher load limits.


* A broken belt is toast. Just chuck it, put on a new one.


* Belts are cheap and easy to replace. Carry at least one. They are literally $10 or $20, and take 10 minutes to replace.


* The only serious risk is that on most engines, the belt also drives the water pump(s) (not on my old Volvo, one of its few positive features!). This means that a failed belt requires an immediate engine shutdown -- not good in a narrow channel!



Harry

[Stu Jackson]

Originally Posted by ferrailleur

Nobody mentioned the strength and critical alignment of the alternator bracket.... I have the old original set up on my boat... Should I be scared as they say?


https://www.catalinadirect.com/index...t-retrofit.cfm

yes, you should. Why? When the alternator smashes down it hits your engine gear case cover. Those covers are hard if not impossible to find. For the lack of eliminating the cast OEM bracket for a few hundred dollars, you get to spend $10,000 on a new engine.


There are tons of writeups on this issue, here's one I wrote:

• Alternator mount/bracket upgrade Important safety upgrade for M25 (not XP) owners by Stu Jackson

[wsmurdoch]

Originally Posted by LargeMarge

Why do you have broken belts? A set or two of new == unbroken == belts makes sense to me. What do you do with broken belts? Can you repair them? Are your broken belts good for spares? How long do your repaired belts function compared to new?

Please, post photographs of the repair process.

My belts break because I am running a 105A alternator with a 1/2 inch vee belt. At the high end of the alternator's capacity, the load is at the limit of what the belt can handle. I have some belt dusting at low engine speeds and high alternator output. Under these conditions the belt sees its maximum loading. As the belt wears it sinks deeper into the sheaves, becomes looser, slips, heats, and produces still more dust. I then re-position the alternator to tighten the belt and the process begins anew. If I continue too long or over tighten the belt to prevent its slipping, the belt breaks. The belt falls to pieces and is not repairable. It is trash. I carry spares and replace the broken vee belt with new. I've never photographed replacing a broken vee belt.

Bill

[01kiwijohn]

At that Amperage, Bill, you are above the capacity of that belt. That's why it fails so frequently. Tightening it as much as you say will also have a detrimental effect on your engine coolant pump bearings. Really, the ultimate solution is to go with a flat, serpentine, or double belt (not as good). or...just continue to carry a bunch of spares and put up with it.
Depending on the size of your battery bank,you may be able to change to an 80 Amp alternator, which will be withing the operating range of a single belt, especially if you have a remote regulator incorporating a "soft start" feature.

[wsmurdoch]

Originally Posted by 01kiwijohn

At that Amperage, Bill, you are above the capacity of that belt. That's why it fails so frequently. Tightening it as much as you say will also have a detrimental effect on your engine coolant pump bearings. Really, the ultimate solution is to go with a flat, serpentine, or double belt (not as good). or...just continue to carry a bunch of spares and put up with it.
Depending on the size of your battery bank,you may be able to change to an 80 Amp alternator, which will be withing the operating range of a single belt, especially if you have a remote regulator incorporating a "soft start" feature.

Yes. You are right. Especially at low engine speeds with a full alternator load; the the tight side vee belt tension soars. The arithmetic is unavoidable.

As I said in post #3, in 14 years we have had a few belts break. I de-rated the alternator using the "Amp Manager" function of the Balmar/Xantrex regulator and installed a switch to cut the horsepower requirement to 50% using the "Small Engine Mode" when we are motoring all day rather than just charging the batteries at anchor. These not only save wear on the belts but also reduce the alternator temperature all at the unfortunate expense of a slower battery charging rate.

I have a KriKit gauge to check the belt tension with. Belts are easier to replace than water pump or alternator bearings. There is no upside to ruining bearings.

We have over 10,000 hours on our Yanmar 3HM35F, so it is probably not worth the effort to change to a serpentine belt right now.

Bill

[sailingharry]

Originally Posted by wsmurdoch

I have a KriKit gauge to check the belt tension with. Belts are easier to replace than water pump or alternator bearings. There is no upside to ruining bearings.

Just got a KriKit off Amazon this year for $12. What a wonderful addition to the tool box! No more "hmm.... is this tight enough"

[01kiwijohn]

I've had good luck with a Chinese Hitachi from a company called DB Electrical. https://www.dbelectrical.com/starters/
They had an 80A alternator, single belt pulley and a Yanmar mounting. It cost me about $80, delivered to my door and it's lived for 3 years so far.
I did have the original checked over & bench tested so keep it as a spare,
hope that helps

[waterman46]

OK, you have read about a dozen common alternator failure modes. Here's one not so common. While hooking up wires to an alternator I accidentally dropped a small washer. Couldn't find it anywhere. Found another washer, completed the connections and all was well for a few hundred hours. Finally had alternator failure. Tech in repair shop found my washer neatly shorting out some windings. Guess washer fell into the alternator's air vent slot somehow.

[fschaefer4]

Ask a question around here and man-oh-man do you get a deep dive on the subject in question. I’ve gone through and listed all the point in this thread so I can reference whine I need to.

This weekend I plan on using the alternator on my truck as a guinea pig for testing along with regular battery tests. If I’m gonna make it on a boat, I’ll need to know my stuff. Thanks again guys.

@Waterman46- talk about a tiny thing taking you down. If you were out in the middle of nowhere, that could have been a different story.

[wsmurdoch]

Originally Posted by 01kiwijohn

I've had good luck with a Chinese Hitachi from a company called DB Electrical. https://www.dbelectrical.com/starters/
They had an 80A alternator, single belt pulley and a Yanmar mounting. It cost me about $80, delivered to my door and it's lived for 3 years so far.
I did have the original checked over & bench tested so keep it as a spare,
hope that helps

DB Electric is an interesting company. They began as an automotive electrical shop in Boones Creek, Tennessee a couple of miles from my house where they repaired alternators, generators and starters. Over a period of three or four years their showroom changed from shelves to cubicles as their internet business began and grew. They have now moved their internet operation to a nearby location in Kingsport off I-26.

Bill