Yearly Alternator Dying
 

So -- for the third year in a row, my alternator stopped charging. I'm starting to think this is more than bad luck. It's a minor inconvenience since it is ridiculously easy to change on the boat but I figure there must/may be something else going on. It's ridiculously simple wiring and it all looks like new, any ideas on what to check?

At least two of them were warrantied....

The 1990 Corvettes had a problem with heat and primary
side wiring. The fix was a higher capacity alternator and
bigger primary cable.

I have the same flippen issues! It drives me nuts! It's a one wire alt setup.

POS Alternator company or Charging more than they should or switching most battery selectors while running.

95% of the time it's a POS alternator.

Oh, and warranty, smoranty. That means, who the f*k cares about warranty if all they do is replace the bad one with another bad one.

Exactly. Two new batteries and a good Mondo alt this time. I'm tried of messing around.

its probably the voltage regulator failure could be bucking each other on a twin engine setup..for start up i put my switches on all or both. after running i put one switch on 1 and the other on 2

Running down a battery (stereo) then using alternator to charge drained battery will overheat and kill it.

Clean you grounds and make sure theres no paint on any of the mounting surfaces of the alternator. The same thing kills amplifiers too.

Since we're here is their any preferred make of batteries? Or is this the same question as what's the best oil for my boat.

Sears Diehard platinum or odyssey group 31 size since you asked.

I have a dual battery setup on a single engine boat. One starter battery, and one deep cycle. I always start and run on "all" on the battery switch. Once anchored I only run the stereo off the deep cycle. On returning I start and return on "all" for charging. I don't have a killer stereo or anything, and most times I don't even have it on. I'm going to double check the connections, and instead of swapping it out, I'm going to bring it to a shop that rebuilds them so I can at least pinpoint the problem. I'll report back what I find.

one word...china, junk parts see it all the time...idiots can't even make a decent fortune cookie

BBC Libertator - I'm not sure if I'd connect a deep cycle and a starting battery together. I'd either charge both with an isolator, or better yet, wait till you get back and put a charger on the deep cycle.

Starting and deep cycle batteries are two different animals.

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Re-reading your post, you may be better with two starting batteries as a deep cycle is meant to be run down and then recharged.

Connecting two of the same batteries together is only okay if they are in the same exact condition. When batteries are tied together, the weaker is always taking power from the better. Think of two gas tanks with a fuel line connecting each at the bottom. They are always going to be equalized, even if you are drawing/using/filling just one.

Main reason for having two batteries with one engine is to have a back up. If you never use it, that's great...just make sure you charge it here and there.

Stop doing that. Never switch your selector switch while the engine is running. Diode killer.

I never change setting with the engine running, ever. Bad typing, I change to "all" then re-start.

I thought this as well, but this is always how I have run my boats -- certainly doesn't make it right, that's for sure, but I've never had issues in the past, guess I was just lucky. The only other way I have run a dual battery set-up is with 2-deep cycle batteries. Never had an issue then either. I do have another identical deep cycle battery at home for a trolling motor I could throw in it. All the batteries were replace last year.

EDIT -- they just called, the voltage regulator was fried and the switch was cracked (have not seen it yet). $319 late I'm hooked up with some brand new junk. The alternator was repaired and I am now keeping the repaired alternator as a spare as I purchased a new one, and a new switch. I'll also consolidate batteries.

What series alternator? I built a mefi4 efi 1974 Transam, has giant electric fans, fuel pump, engine oil circulating pump, lots of draw. Used a 140 amp powermaster 10SI alternator. It draws around 60-70 amps when everything on vehicles running, have pissed around with 3 replacement alternators as they cook every 20-500 miles, have learned that they can make any alternator put out 140 amps but just like a cheap Lincoln welder they have a VERY short duty cycle and overheat when under a load, especially IF you run battery down. Last one cooked in 20 miles because we ran fans and oil pump with car sitting at chassis dyno so when we started it the alt was under full load, it simply couldn't EVER put out 100+ amps for more than a few minutes without cooking. Went to a 12si, just as bad, went to a modern style one with external AND internal fan, never has a problem since. My boat also has a lot of draw, put a 105 amp Mondo on 13 years ago with internal/external fan and I run battery's down to point boat barely starts and its never cooked, FWIW, Smitty
Shooting it with infrared under full load surface temp was 300+ degrees, there are no windings, stator, diodes, regulators that can take that for long.

I have 3 group 27 marine dual purpose batteries in my boat. Decently large stereo. Used to instantly kill the puny stock Mando alternators. I had a local guy build me a 100a one wire Delco with the marine housing and all new internals for under $100. Did the same for the old man's sea Ray with same issue. Neither one has given me a problem since.

Our Powermaster 8102 have worked flawlessly for 10 yrs. Summit sells for $189

They installed a powermaster (not sure of the model #) but it was $189.99 -- they said it was an infinitely better unit than what I had. The previous one was only a 70a!!! Anyhow hopefully that, combined with a battery swap will end this ridiculousness...and if not, I now have a spare pile of **** too :)