Alternator.... turning internal to externally regulated

dlochner · Oct 21, 2020

Is the alternator the infamous Hitachi super dumb alternator? I seem to recall an article in MarineHowTo.com suggesting it could be converted, but wasn't easy.

Let us know what you find out. I have one those sitting in my basement.

jssailem · Oct 21, 2020

I remember the same info from MaineSail. Not sure where I saw it. May have been on of his writings here on the Forum. Worth a search if you do not find it on his website.

Rich Stidger · Oct 21, 2020

I did this conversion years ago on a Motorola alternator. If you are mechanically and electrically handy, it is a hour job. What you need to do is to split the alternator case. First mark the case halves so that you can reassemble exactly so that your external connections will be in the same relative position. The rotor will remain in the front half with the pulley. The rear half will have the field winding, the internal regulator, the diode trio, and the rectifying diodes pressed int the case. You need to locate the connection between the regulator and the field winding. Break that connection and bring both connections out of the case with extension wires of different colors so you know which is which.
Re-assemble the halves of the case back together. The trick on getting the brushes back into their holder is to look for a small hole on each side of the brush assembly. While pushing the brushes back into the holder, insert a straightened paper clip through the holes to hold the brushes in a retracted position. A cake tester also works very well instead of a paper clip. This paper clip must be long enough to stick out of the case after assembly. Then you can easily slip the case halves back together. After you have secured the case halves, pull out the paper clip and the brushes will snap onto the rotor.

To use this alternator as an external regulated unit, connect the field connection that you brought out to your external regulator field control. The connection to the internal regulator should be taped off to insulate it. If you need to revert to an internal regulated alternator, just connect the two wires you brought out of the case (the field and the internal regulator) together.

Justin_NSA · Oct 21, 2020

When you get it converted, you may want to dry fit it and check the pulley alignment as well as the operation. You may need shims, bracket etc. Better to know before you need it if everything works as expected.

Maine Sail · Oct 21, 2020

NYSail said:
Hello all,
So a couple of years ago I upgraded to a Balmar 150amp with mc 614 regulator. The alt I removed (80 amp) was reported to have been replaced 1 year before I bought my boat and appeared to be working fine. So what I would like to do is have this converted to externally regulated so I have a spare I can carry with me... basically plug and play. Is this a basic job that any reputable rebuild shop can do or should seek more of a specialist like Maine Sail do the job. Shame to have the thing just sitting worthlessly around.

Thanks
Greg

Not an easy task at all on those alternators. We build from the raw component level and we are having internal components specifically made for us to build the AMP-IT 80-ER for external regulation.. If you want a spare you can buy one already built and then likely sell yours used, as a spare for someone else. Hitachi pulled out of this market so all that are left are cheap Chinese models. I am sure someone would want a genuine Hitachi as it is a far better alternator than what you can buy today.

Stu Jackson · Oct 21, 2020

NYSail said:
Shame to have the thing just sitting worthlessly around.

jssailem said:
I remember the same info from MaineSail. Not sure where I saw it. May have been on of his writings here on the Forum. Worth a search if you do not find it on his website.

Converting a Leece Neville Alternator to External Regulation by Maine Sail
Converting An Alternator To External Regulation

NYSail said:
Yes.... it replaced the original super dumb Hitachi..... probably just as dumb.

Only if it, too, is an Hitachi. I've posted this dozens of times before. I'm doing it again for those folks who haven't seen it and don't know what you knowledgeable skippers are talking about, it is for those with Yanmar engines who are just getting into Boat Electrical Systems. Only YOU know if it is one. If it isn't, then you should be able to convert it.

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.. Any battery at any state of charge 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:

Musings Regarding External Voltage Regulation

and these, too:

Hitachi Alternator and Smart Regulator Instal Question - Cruisers & Sailing Forums

Most practical way to upgrade Yanmar alternator? - Cruisers & Sailing Forums