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Life expectancy of alternators

Frank Langer

1984 Ericson 30+, Nanaimo, BC
We are planning several sailing trips next summer to places where I likely can't buy parts or get mechanical help, so I'm trying to proactively fix/replace/learn to repair anything I can on our E30+ boat with the 16 hp 5416 engine.

Can anyone give me an approximate life span of the 55 amp alternator that comes stock with this engine? The engine has about 850 hours on it. I would prefer not to have to carry a spare alternator, but could do so if ours is nearing the end of it's expected life. I'm hoping that someone can tell me they last alot longer, but I really don't want to be stranded in a beautiful anchorage with dead batteries.

I did clean/tighten all the connections on it recently, and noted that it spun freely with no bearing noise, and it has been charging properly, so everything seems to be fine for now. But I have experienced the alternator on our vehicles being fine one day, but no longer charging properly the next day, with no apparent warning, resulting in an expensive replacement.

Any ideas or advice?

Thanks,

Frank
 
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Captron

Member III
Alternator Life

Personally, I prefer to carry a spare alternator and a spare regulator. However some folks carry parts kits; (bearings and diode packs). I suppose repair kits weigh less and take up less space. I also carried a spare Delco wiring harness so I could easily adapt any old automotive alternator to my set-up. Alternators are commonly available from auto repair shops throughout the Caribbean and Bahamas. So maybe packing spare cash makes more sense. Also I have had parts flown into the Bahamas quite reasonably and it usually only takes a day or so if you use the right connections.

One time we had ordered a hot water heater from West Marine over the phone and had it shipped to Rock Sound on Eleuthera. It took about a week or 10 days but it was shipped from California via Fed Ex.

Another time I got a warranty replacement computer for our RayMarine autopilot virtually overnight at George Town on Great Exuma. That time the replacement computer was overnighted from New Hampshire to an agent in Ft Lauderdale who put it on a small freight plane and it arrived at Customs in GT the following day. Shipping cost was $24 not counting the overnight or import duties.

I would also add that alternators rarely last until they fail from old age. Usually it's stray voltage spikes that take out a diode or kill the regulator.

One time my regulator went out and testing showed that I could make the alternator charge ok by just turning on the field wire manually. Fortunately, I had a small on-off toggle switch in my spares bag that I was able to wire in so that I could at least manually control charging. I ran that set-up for a couple of weeks once but it did require careful monitoring of the battery voltage.
:egrin:
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Thanks, Capt Ron,

So what causes the stray voltage spikes that ruin the alternator or regulator? Is there some way to minimize the chance of that happening?

Also, are marine alternators different from automotive alternators (ie. different casing, tougher, etc.) or can one simply replace them with an automotive one if the size is similar?

Frank
 

Glyn Judson

Moderator
Moderator
Are marine alternators different?

Frank, Speaking only as a Yanmar engine owner, I can tell you for a certainty that the 30 amp alternator on my 1988 Yanmar 3GMF is IDENTICAL to one from a Mitsubishi(??) automobile. I know this for a fact because when I had mine rebuilt, I specifically asked my local alternator repair shop guy to note that as they rebuilt the very one I took in to them. I returned the next day and asked the technician that did the actual rebuild if there were any difference and his reply was that they were the same in every manner. I even asked if there were spark baffles or the like, his answer, no. I had to have this alternator rebuilt because 30 amp alternators are no longer available except new $$$ from Yanmar. I didn't want a larger unit as the 30 amp is paired to the HP output of the 3GMF. Hope this helps, Glyn Judson, E31 hull #55, Marina del Rey, CA
 

mherrcat

Contributing Partner
850 hrs...that must be after a rebuild, or the engine was almost never used! My '85 30+ M-18 engine has over 2500 hrs on it. Still starts and runs fine. I'd like to have it rebuilt sometime, but can't afford it right now.

I did a rather simplified test on the electrical charging system last weekend. Without removing it I can't really get to the back of the alternator to check the output there, so I monitored the battery charge while running the engine. In just a couple of minutes of the engine running the charge on the batteries steadily rose to 14v, which according to the eletrical book I was referencing indicates that the alternator is charging.

So, according to my alternator which definintely looks original (a Motorola by the way) you may have at least 1650 hrs to go...

Not sure what the maximum amperage this alternator is supposed to put out because I can't see any indication of an amp rating on the label.
 
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Frank Langer

1984 Ericson 30+, Nanaimo, BC
Thanks, Mark

The engine hours are original. It only had 570 hours on it when I bought the boat in 2006 (and service records show that to be accurate), and I added under 300 hours in the past three years, though will be using it more now that I am retired. I hope to get alot more use out of this engine before doing any major work, but I'm also aware that it's 25 years old, so not quite sure what to expect. Also, I don't want to have a breakdown while on a cruise in some more remote area, so want to do everything I can to keep it running well.

Have you done any work to yours other than the usual oil/filter/impellor changes -- ie. valve adjustment, injector service, etc.?

Thanks again.

Frank
 

ted_reshetiloff

Contributing Partner
Its really not that tough to pull the alternator and take it in for bench testing if you are really concerned. Not sure who you would get to do this but a local shop Mammocs in Annapolis does this all the time. There are probably ones in your area.

Another factor on alt life expectancy is how it is used. How big is the battery bank you are charging? Its going to work a lot harder charging 2 8D's than it will for say a single group 31.

How long is the alternator in bulk charge mode vs absorbtion or float? Longer in bulk charge mode means more time the alternator is working its hardest.

Do you have a "smart regualtor" with temp sensors for the alternator and battery bank? Smart regulators will monitor the temp of the alternator and reduce output if the alternator is too hot. It will also vary the output on the temp of the battery bank, as well as the charging algorithm based on battery type.

How well ventilated is the engine compartment? Keeping the alternator cool is important. I know folks with big charging systems that use dedicated blowers just for cooling the alternator(s). But thats for very large charging systems.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Thanks, Ted

Lots for me to think about!

I have two group 27 deep cycle gel cel batteries, and one group 24 starting battery, and plug into shore power when at the dock. I have a Heart/Xantrax inverter/charger which apparently controls the charge rate. Batteries get used when anchoring out, of course, but we try to ensure they don't get drawn down too far. I rarely motor for hours at a time, so the engine compartment tends to stay cool most of the time (moderate temps in BC, Canada).

I will think about taking the alternator to have it tested, though that does sound like a bit of a pain to do.

Thanks again!

Frank
 

mherrcat

Contributing Partner
I actually haven't done any maintenance other than regularly (probably more often than needed) changing the engine oil and filter. I know I should have the engine checked over by a good marine mechanic, but right now I don't think I want to deal with the cost. (Yeah, I know, pay now or pay more later...) I'm overdue for an impeller replacement and have the parts, just haven't done it yet. I have been checking and replacing the heat exchanger zinc every three months. Changed transmission fluid and would like to do that again soon.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Thanks for your reply, Mark

Some people advocate that "if it aint broke, don't fix it", saying that once you start messing with an engine it creates a chain of things that need adjustment or repair. While I certainly don't want to create a problem, I also don't want to overlook a maintenance item that could reduce wear on the engine or avoid an operating problem.

On the other hand, if you are doing regular oil, filter and impellor changes and periodically change tranny fluid, coolant and check/replace hoses and fan belt, that may be enough if the engine is sounding normal and showing no signs of distress (smoke, leaks, strange smells). But that's only my best guess, as I'm not a mechanic and my technical skills are very limited.

I understand from the manual that timing doesn't need adjustment unless the engine has been worked on, and injectors only need servicing if the engine is running rough, not starting properly, etc. I don't know if valve adjustments are needed at certain intervals, or only if a problem is evident; and I don't know what the signs are that a valve adjustment may be needed.

I tend to worry a bit more about some of the other components, like the alternator, starter, regulator, batteries, etc. as I understand that they often don't give much warning and can leave you stranded, whereas engine trouble usually develops more gradually.

Maybe someone can shed some light on all of this....:confused:

Thanks again for your reply.

Frank
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Not much light to shed, but maybe a little.
I have had both the factory alternator and the starter overhauled as preventative maintenance issues over the years. I figured that at about 1000 hours it was time. The result that stands out in my mind is the starter. It worked before removal, but, when restored to the engine it worked noticeably quicker and better!
To change out the starter takes a socket, a wobbler, and an extension, and some creative swearing, FWIW. The swearing is especially important and must be sized exactly to the task...
;)

LB
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Is that a universal joint for sockets? Had not heard that one.

You are more correct than I. I looked it up and Sears calls it a flex joint. Handy, and sometimes nothing else will do.
LB
 

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Emerald

Moderator
wobblers

Hi Loren,

you were actually more correct than perhaps you realized. There is a "wobbler" extension that lets the socket flop around on the end and is often a nice alternative to universal joint.
 

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ted_reshetiloff

Contributing Partner
So Frank if I understnd you have 2 group 27's for your house house bank. Thats roughly 180amp hour bank. If you want the batteries to last you should not run below 50% depth of discharge, leaving you with about 90 amp hours of usefull capacity. Others may chime in here but I seem to recall the goal of 25-30% of your battery bank being used for alternator sizing? That would mean you should be looking at about a 45amp alternator. OEM you said is 55amp which probably operates around 25-30amps sustained. This leads me to believe that you are probably not over taxing your alternator. One thing you did say has me a little concerned. You mentioned that you are using sealed Gel cell batteries. Gels are rather particular on the voltages at which they like to be charged. You did not mention anything about your alternator regulator. Your Xantrex charger does not regulate the alternator unless you are using a Link 2000R panel, which you did not mention, it only regulates the AC charging. If you are using the stock internal regulator you are likely charging on a less than desireable basis. What does that mean? Well it simply means you wont likely get as long a life out of the battery bank as you would if you had a smart external regulator. It also means you will likely need to run that engine a lot longer to replace the amps you are taking out while cruising. Probably not that big of a deal if you are just a weekend warrior but definately a concern if you are cruising on the hook for extended periods. That regulator will never keep up with your use and after a few days your batteries will be flat.

Ok a big factor we have not looked at here is just what are your electrical demands in a given 24hr period? If you do not have 12v refridgeration you are probably in pretty good shape with the 2 group 27's. On my E38 the fridge draws about 5amps when running and due to the poorly insualted factory ice box it runs about 50% of the time. That means the fridge takes about 60 amps every 24 hours. I have 2 group 31's which give me about 100 amp hours of usefull capacity so after the fridge I have about 40 left to play with. Thats for stereos, instruments, water pumps, bilge pumps. running lights, cabin lights etc. You can take the time to list the demands in amp hours of every device on the boat and then double that to determine the actual battery bank you should be using. Remember OHM's Law? Amps= Watts/Volts. So a 25 watt bulb at 12 volts draws 2.08 amps. Leave it on for 4 hours and you have just used 8.32 amp hours from your bank.


Last piece here is to have a good amp hour meter like a link 10 to accurately keep track of how many amp hours you are taking out of the battery. Then you will know when you need to run that engine to avoid going below 50% depth of discharge, and also when you can shut the beast down. All of this sounds like a lot for 30' boat but its really not that complicated and in the end you will likely save yourself money by never having to replace batteries. I am on 9 years on my house bank. Just before our cruise to New England this summer I had the bank tested. The electrician's fancy meter measured CCA in the bank and it came out at 95% of original! Thats on 9 year old batteries that stay in the boat year round.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Ted,

Thanks for your very thoughtful and detailed reply. Your assumptions about my set-up are generally accurate, though we do have a refrigerator which we run quite sparingly (adding a block of ice before we leave, minimizing open/close, etc.). We are quite frugal with lights and other electrical stuff, especially when at anchor. I have the Heart 1000 inverter with a panel/lights that show amp usage and battery voltage and we monitor the batteries carefully to ensure we don't deplete them.

Our starting group 24 Trojan battery was replaced two years ago, but our two group 27 house batteries were bought in May, 2001 and were still very strong when tested last year. I am thinking they must be due for replacement soon, especially if we are going to be anchoring out more this summer.

I'm not sure how much difference an external regulator would make, nor how to install one to replace my current set-up, so I'll try to find out a bit more about that.

This stuff is complicated, especially for those of us who don't really understand it.

Thanks again!

Frank
 

ted_reshetiloff

Contributing Partner
External regulator is pretty simple to install and you can set it up so that your internal regulator becomes a back up should the external fail. Sounds like you can see the amps you are pulling so you should also be able to see what your existing alternator is putting out which is a pretty good way to keep an eye on how well the alternator is performing. Take a look at:

http://www.xantrex.com/web/id/107/p/1/pt/7/product.asp

or

http://www.balmar.net/page15-maxchargemain.html

As for the existing group 27's any decent marine electrician should be able to test them for you and tell you how many CCA they have. You then compare that number against what a new group 27 has and can get an idea of how close to new your battery is. Load testers can give you some of this info too.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Thanks, Ted

These look very useful, but they are not cheap!! I'll have to start saving my pennies again.

Frank
 
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