Alternator advice

[Trojan]

If you have a Sams Club in your area,they seem to be the cheapest for 8Ds.Bill

[Capt K]

Cedar Island Marina in Clinton

K

[divert00]

Sometimes if it looks like a duck and quacks like a duck, it is a duck. Alternator was worn and had a broken winding. It must have crapped out in 1st hour off the hill. A rebuild cured it all. Thanks for the helpful advice.

[Genesis]

BTW I just pulled one of my blower-drive alternators. I'm tired of the damn oil leaks and may just put a blanking plate on that engine's mounting point and LEAVE it off.

Then again I have a good (non-leaking) alternator on the other side, a combiner, an AC charger and an alternator on the genset, all of which work - so I have three charging sources without that engine's contribution.

After I make up a nice blanking plate out of aluminum I will decide whether to put ANOTHER seal in that monster or whether I just take the alternator to a nice shop somewhere, have them go through it from top to bottom, and then stuff it in the "spares" box on board and NOT re-install it for the present. This way if the other side craps out I have an immediate-swap spare, and still have my three sources of charging for both banks....

I kinda like that plan.....

[SKYCHENEY]

What about switching to a belt driven unit?

[Genesis]

Actually a good idea, but a pain in the arse to implement.

I would have to weld up brackets (there IS a front motor mount location unused on my engines, so there's a place to bolt the bracket once made), and then fashion a belt guard so the next time a surveyor is on board he doesn't shat kittens when he sees the setup.

I'm thinking about it, as there IS room on the port side of each engine to mount it, and the front pulley is completely unused. It does solve all the problems at once, and also allows me to run externally-regulated alternators, which is a huge bonus. Plus a regular alternator is WAY cheaper than those Leese-Neville things that are direct-drive, and they're available darn near anywhere in the world.

The question is, do I really need more than three charging sources on board when the mains are running? Even with the genset busted I've got the one on the other main. If THAT's busted (e.g one engine AND the Genset out, and the wrong one) then I've got nothing, but in that case I've already had two serious failures - and my engines will still run, as they don't require electrical to operate.

If I've got the other Leese unit rebuilt and on board then a swap is a matter of waiting until its not 130F in the engine room and changing it out. I can swap one of these alternators in less than 20 minutes; its not difficult at all.

[Norm Mayer]

Just a quick battery primer for those interested: When checking the OPEN CIRCUIT VOLTAGE of a battery (everything is off, and batteries have sat for a while) you are NOT checking the condition of the battery. You are checking the state of charge ONLY. If you fully charge a sulfated battery (meaning worn out) it will have a reading of 12.6 volts. Same thing as using a hydrometer (an even more accurate method of checking state of charge). State of charge does NOT indicate the condition of the battery.
A "load test" with equipment not available to the average DIY is the best way to determine the condition of a battery; how many amps of current can it deliver without dropping below 9.6 volts. A new way of testing the battery is a small, hand held device that tests the Capacitance of a battery offers the next generation of checking a battery. As an old dog, I have yet to be convinced this will give accurate results to a battery's condition, but many technical articles says it works. Who am I to argue, except that personally, I trust the load test.
For what it is worth,
Norm Mayer aboard Runaround Sue

[Genesis]

Yeah, but if the battery will roll over these old Detroits, its not in TOO bad of a shape. Those things require some serious amps!

A "quick check" for battery condition is to hold the STOP button and crank for 10 seconds straight, with what you believe is a full charge. If you can do this and the engine is still spinning at close to its starting RPM (as determined by the sound of the rotation) when you began cranking, the battery is almost certainly ok.

[Norm Mayer]

I agree, Genesis. Cranking the engine is a "poor man's" load test. Doesn't hurt to watch the final voltage at the end of a 10 or 15 second cranking test, either. It should remain above 9.6 volts. Also, do the test on a cold engine, as the engine will require a higher amperage to turn it over, giving a better load test for the batteries.

[SKYCHENEY]

Karl,

If you are worried about a surveyor seeing your unguarded belt, then it would also seem that you would worry about him seeing an engine with no alternator at all. I agree that you don't need both alternators, but there are many other redundancies on board that we don't "need". We have these things because we know that there is a difference between "getting by" and actually doing the job right. You don't really need that fancy fuel filtration system either, but it sure is nice.

I think I would either convert to belt drive or put up with the gear drive units, but not leave one alternator off altogether. That just doesn't seem right for some reason, even though it would probably be okay in most instances. Maybe I'm just too much of a perfectionist or perhaps I would change my mind if I had gone through what you have with these gear drive units.