Hitachi 180-03C not charging

[glossa]

We're on our third alternator and none of them seem to charge.

About a week after we bought the boat in 2015, a 1990 Catalina 42, we had to replace all of the batteries as well as the charger. We also replaced the alternator which didn't appear to be charging. Since we typically weren't cruising for longer than a week, shore power was adequate to re-charge the batteries and so I didn't realize there was still a problem.

Last summer, the batteries died while we were cruising in the San Juans. Voltage at the batteries and at the alt did not increase with the engine running at any RPM. Not having time to properly diagnose the problem, we replaced the alternator again at Roche Harbor, with no success.

Last week, I had our second alternator bench tested (we still have it) and it passed.

I checked voltage again and here are the readings that I get:


Engine Off Engine On
@Batteries 12.66 12.42 (Idle)
@Batteries 12.66 12.36 (2K)
@Alt 12.43 12.25 (Idle)
@Alt 12.43 12.24 (2K)

I also get voltage at the R terminal, over 12 volts. I'm unsure of the role that the L terminal plays; based on my reading, it seems to depend on the application. Even the breakout diagram in the engine compartment shows that the blue and black wire goes to the tach. But when I disconnect the R-L terminal, the tach still works, so I think the sensor must be at the crank.

I guess I could try swapping # 2 back in... What else can I test for?

[Stu Jackson]

Don't know if you've ever seen this:




Hitachi/Yanmar Alternators: (by Maine Sail)

Some alternators though, such as those made by Hitachi and found on Yanmar diesels, are dumber than a pound of beetle poop. Actually, to the alternator, they are pretty smart but to your batteries and the speed of charging they are flat out stupid. Why?

Hitachi alts with dumb regulators, and some others, limit voltage but also reduce voltage based on alternator temperature. This is a self protective feature installed in the internal dumb regulator to prevent the alternator from cooking itself. Remember voltage is the pressure that allows more current to flow. So, if we reduce the absorption voltage, then we also reduce the current the alternator is supplying.. The battery simply will not accept the same current at 13.4V that it did at 14.4V and as a result the alternator will run cooler. What do you suppose this does to your batteries over time.......?

The problem is that when cold you will get 14.3V to 14.4V out of the Hitachi but as the alternator heats up the dumb regulator begins to reduce the CV/voltage limit based on the alternators internal temperature. It is not uncommon to find a Hitachi alternator at 13.4V when hot. This is REALLY, REALLY DUMB....

If you have a dumb regulator, and notice the voltage dropping, it is likely a temp compensated dumb regulator. Get rid of it or plan to buy new batteries more often.

If you have a temp compensated alternator or a Hitachi alternator on a Yanmar you really are in dire need of external regulation if deep cycling a larger battery bank.

This is from:

http://forums.sbo.sailboatowners.com...d.php?t=125392

and these, too:

http://www.cruisersforum.com/forums/...on-125843.html


http://www.cruisersforum.com/forums/...or-142083.html

[glossa]

Thanks. Yeah, I've seen this. The fact that it doesn't seem to charge at all makes me think that something else is going on.

[osprey877]

I had same problem with my alternator. Turned out it was the regulator that was the problem, not the alternator. My alternator (not an Hitachi) is externally regulated so is fairly easy to determine whether problem is alternator or regulator. To test, check if there is any voltage on the field wire that runs from the regulator to the field terminal on the alternator when the engine is running. If not, the regulator is likely the problem. On my installation, when I connected a wire directly from the battery + terminal to the field terminal on the alternator the alternator began charging instantly at the required 13.5 volts. I had the regulator tested and repaired for about $90 and it all works fine now. I don't know if you can remove and test the regulator on your internally regulated alternator but if so, try the above test. Don't leave the wire connected to the field terminal for more than the time necessary to test the alternator output as the current is unregulated and will cook your batteries if left on for any length of time, although in an emergency you can use it to charge the batteries provided you keep monitoring the battery voltage and disconnect the field wire once they are charged.

Nigel Calders book on Marine Electrics has a good chapter on alternators that you might find useful.

Hope this helps.

[Redline452]

Check the ground connection of the alternator negative...



I had a poor connection at the engine-block end of the cable on my 4JJH2TE (Hitachi 85 A alternator) which caused a voltage "drop" which effectively raised the negative side of the alternator a volt or two above ground. Measuring engine ground to alternator + showed about 14, but there was very little current flowing because pof the loss on the negative side. Tightenning the bolt about 5 degrees instantly increased charging by 50A.


The root cause was the same bolt being used for multiple (4+) terminals plus a cable clamp (shouldn't share a fastener for both electrical and mechanical purposes) that aged, heated up and corroded. Almost melted through one of the cables under the clamp, so double bad. But because the high capacity alternator is NOT case ground, unlike its smaller cousin, the negative lead is critical.


Good luck.

[glossa]

Apologies for not following-up on my OP.

There is a white two-wire plug that goes into the side of the alternator and runs into a harness. The harness runs to the back of the engine where there is another plug that can be taken apart. I had a hard time getting continuity through these wires.

It seemed like the plug going into the alternator was suspect. It's been so long that I don't remember what the wires were for, perhaps the field windings?

Anyways, when I replaced that plug with spade connectors, it started charging, probably for the first time since we bought the boat in 2015! I could tell because the regulator was reading 14 volts.

Now I just need to find a replacement plug.... spade connectors are not ideal.

[Stu Jackson]

It's a standard Ford plug, and any auto shop or alternator shop will have them.