Alternator issue

[Swiss sailor]

Hi all
I'm in need for help to resolve an issue with my alternator.

Here is what I have:
The engine is a 1999 Yanmar 4JH2E whitch came originally with an 80 Amp (Hitachi) alternator. I have a 120 amp 12V starer battery (new in November 2013) and a new house battery bank consisting of 2 x 2 6V Duracell ECG2. The battery charger is a new Sterling Pro Charge 60Amp unit.

Here is the problem:
The built in alternator did not charge anything anymore. I had it bank tested and it is shot. So I bought a 50amp alternator (from Spydermarine), and installed it. Surprisingly, the new alterator is not charging eighter!

What did I try alredy?
- I measured the voltage at the alternator while the engine and the battery charger was off. The voltage is between 12.6 and 12.8 volts, the same voltage as when measuring at the starter battery directly.
- I rang through the cables from the negative shunt to the ground at the engine and there is connectivity (why else would I have volts on the alternator..).
- I did clean all the cable connectors with a wire brush to remove corrosion.
- When switching the battery charger on, the voltage on the battery increases to 13.8 volts.
- I removed the new alternator and had it bench tested. It is charging on the bench.
- I increased the rpm on the engine from 700 to1000, 1500, 2000 and 3000 rpm. Nothing changed. Not charging.
- I turned the refrigerator, the lights etc. on to have some load on the battery (7amps were drawn) and ran the engine at the different rpm's again. Not charging.

So I called a marine electrician from the yard to help me out. We whent trough the whole procedure again - with no success.

I'm looking for a hint, something I'm overlooking or I could test to find the reason why the alternator is not charging. Any help is appreciated!
Thanks!
Marco

[twinboat]

First thing, get a new marine electrician.

Just a shot in the dark here,
When it was bench tested, did the tester ground the case or use a ground terminal. Some alt`s have an isolated ground that needs to be hooked to ground.

Sent from my VS840 4G using Cruisers Sailing Forum mobile app

[Swiss sailor]

Twinboat,
he layed the alternator in a steel fixture. Can be, that the fixture was grounded. I have very little knowledge on electrical stuff. So you think that I should connect not only the negative stud from the alternator but also the alternators housing to the ground? I would thinking that the fixture of the alternator to the engine would ground the housing of the alternator already?

[Stu Jackson]

IIRC Hitachi alternators are different than most. IIRC, too, Maine Sail, a frequent contributor here, has discussed this on this and other boating forums (sailnet and sailboatowners.com). I would either do a Google search on "Maine Sail Hitachi alternators" or on those websites, instead of reinventing the wheel. Good luck.

[bill good]

What is the warning light doing? Two alternators doing the same thing. Some times the warning light is needed to start the charge. Keep your old alternator & get it retested.

[Swiss sailor]

Bill,
At the engine control pannel, the warning light is not functional. Do you think I need to replace this bulb first?

[Stu Jackson]

Originally Posted by Swiss sailor

Bill,
At the engine control pannel, the warning light is not functional. Do you think I need to replace this bulb first?

If it is part of the excite circuit, of course.

There is a great "How alternators work" handbook on the internet. Google it. "Alternator Handbook" is what it's called.

[Swiss sailor]

Ok, I'll change the bulb. I found pictures from the back of the alternators (old and new). Just if this could add an idea...
The tech support told me to connect the ground wire to the E-screw.

[chuckr]

i can only tell you what happened to us -- we decided to upgrade our voltage regulator to a sterling and just could not get it to work -- we had a jeanneau electrician try to get it to work and just could not -- and he spent a lot of time on it - 2-3 different occasions - we went back to our old one and all worked
maybe we got a bad sterling - who knows

for what it is worth

[smac999]

E screw is fine for ground. it should work with no ground wire anyways though as it's bolted to the metal engine which is ground.

typically the yanmars have 2 small wires. one is ign 12v and one is lamp 12v.

unplug the plug. turn the key on. you should have 12v at both wires. if your light bulb is shot. one won't have 12v. and the alt won't start

[Swiss sailor]

Thank you all for your inputs!
I've been on the boat this afternoon and changed the bulb at the engine pannel. And guess what- the alternator is charging!
Thank you soo much for your help! Great help, great forum!
The only thought I had was like- do I realy rely on a bulb at ghe pannel? Is this normal? Or could it be wired differently, less prone to failure?
Marco

[Nicholson58]

Just a silly question. Where is the voltage regulator? Many of these have an external regulator. When we started operating our boat, new batteries etc. we found the alternator was not charging. Turns out the alternator had 16 of 18 diodes blown (guess lightning strike). That rebuild at a truck ALT shop only cost 60 bucks. Once installed, still no charging. Our charge controller/voltage regulator was an external Xantrex. A check showed it was dead. I replaced it with a Balmar & success. These things are really basic - works or doesn't.

I agree regarding "find another electrician".

[bobofthenorth]

Just to pile on a bit - if your "marine electrician" couldn't figure out something this basic then he is a complete idiot. If you can't bring yourself to tell him, have him phone me & I'll tell him for you.

[Swiss sailor]

Well, Bob, effectively there were two electricians abord. The forman and the worker. both of them did not find the cause. It's probably just too hot down here in the South ;-)

[hlev00]

Yes. The light is critical. Well, not really the light but the current that result when the circuit is completed and the light comes on. On yanmar alt there is a T plug that brings this to the back of the alternator. Read the earlier reference on alternators.