Hitachi Alternator and Smart Regulator Instal Question

[Stu Jackson]

Meck, my apologies if either one of us misunderstood the other.

Your question had to do with Hitachi alternators and connecting an external regulator.

I provided you with as much information as i could, and simply asked if you'd read the material, because your followup question seemed to indicate to me that perhaps you may not yet have had the time.

I don't think MS was knocking an Hitachi alternator, but rather providing the information you needed to make an informed decision on answering your OP.

Originally Posted by Meck
So, what you are saying is the 3 stage smart regulator can not improve charging capability when used with an automotive class alternator?



The answer, included in that link, was that a 3 stage regulator CAN improve performance, but that the size of the alternator IS important to avoid overheating the alternator based on the size of the battery bank and its SOC.

That's all.

[hellosailor]

Meck, the guys make a very good point similar to saying you can't make a silk purse out of a sow's ear.

Hitachi makes a respectable line of "commodity grade" alternators for the auto industry. The auto industry has specific goals and is very price-sensitive, so the Hitachi alternators are built to a price, for a specific purpose. Built fairly well, within those constraints. Last time I looked (far from comprehensive) that meant obsolete technology and sloppy regulation, which are "good enough" in that application.

But like all automotive integral alternators (regulator built in) they are designed to support one SLI battery, and the loads of one car. An older riceburner might have used a 55A alternator, 60-70A after air conditioning became standard (with higher fan loads), and now? 120A alternators are not unusual as electrical steering and other options become the norm.

So what is a 55A or 60A alternator designed to do? If you run it at "full" rpm, which would translate into a fully loaded engine and probably hull speed on a boat, it is designed to replace the load consumed by the starter (which might be all of one amp-hour) and then power the systems in the car, which aren't a lot of amp-hours either.

It is actually designed, and I quote, "To not overcharge the battery during a long day on the road." It does that by cutting back as soon as it can, and the whole system is designed to sustain full output for maybe 20-30 minutes. At that point the diodes are overheated, because diode capacity costs money. And the small frame that is conventionally used, can't blow off heat because it is small, to fit and to keep low weight. "Large frame" alternators are simply not used in passenger cars, they are too bulky and expensive--but they perform well in other applications. Hitachi? Different market, different product.

So now you put in an external regulator, and it will definitely get more power out of your alternator. Until the diodes overheat, because they weren't intended to run flat out for hours on end. And they overheat even faster, because that alternator was designed for air blowing under the hood, and the boat maker probably didn't bother putting dual cooling fans on it, the way they should have, to help compensate.

And the regulator maker, who doesn't know or care much about your old alternator, hasn't provided any way to reduce power to keep the diodes cool. Because that would require opening up the alternator and installing an internal temperature sensor on the diode frame, and they have no idea which one of hundreds of those you might have.

So what the guys are saying, quite rightly, is that the external regulator will help but there are limits to how far it can help. And like putting nitrous in your engine, sure, that will help, but only until you (might) burn it out.

It would help if you could call Hitachi and say "I've got this alternator, what is the continuous duty rating on it?" and then just don't exceed that. But Hitachi will tell you that is customer proprietary information, and they won't disclose it to you. Ask any non-Japanese alternator maker, like Delco, Leece Neville, etc. and they'll give you full technical specs, including the rpm/vs/output curves, so you can match up the alternator to your cruising speed for optimum charging.

So if you really want optimal charging? And you're using boat batteries, not one car battery? Yes, the really best solution is to put the Hitachi aside as a spare, and replace it with something that won't mind sweating away in the hot engine compartment for hours on end.

BandAids are great, but there are limits to what you can do with just a BandAid.

[MarkJ]

My Hitachi alternator with the original Yanmar paint on it died yesterday.

I have owned it since 2008 and put 3,000 hours on it.

When I bought the boat it had 4,000 hours on it... As a charter boat. And, as I say, it musta been the original one as the paint shows.

So if Hitachi are just cheap, crappy, automotive alternators then its RIGHT for me!

A 7,000 hour life! Thats GREAT!!!



Mark

[hellosailor]

Mark-
Sure, 7k hours, but at what speed and what load? Oh, right, you don't know that.(G)

So don't be too impressed by the longevity of a paperweight. I've had the pleasure of having them long-term in a car, maybe 1000 hours for the first one, then very few (couple hundred?) on the "factory rebuilt" second, then another thousand hours on the junkyard third, followed by, two days on the rebuilt fourth, and again a couple hundred hours on the replacement for that, followed by....

Remember you can burn one out in 30 seconds if you full-field it. Thirty seconds at full output is all they can take. Yours apparently led a more sheltered life.

As a reference? Solid state devices (diodes) when properly chosen and operated, have a typical life expectancy of 100 years. Integrated circuits, like the internal regulator, 1000 years. Hybrid regulators and stuff, still over 100 years. And you cut the life rating in half for every 10F temperature increase over 68F.

So you get what, a tenth of the expected median lifetime? Without the need to replace those pesky mechanical bearings and contacts? Or did they wear out first, as expected?

[Maine Sail]

Originally Posted by MarkJ

My Hitachi alternator with the original Yanmar paint on it died yesterday.

I have owned it since 2008 and put 3,000 hours on it.

When I bought the boat it had 4,000 hours on it... As a charter boat. And, as I say, it musta been the original one as the paint shows.

So if Hitachi are just cheap, crappy, automotive alternators then its RIGHT for me!

A 7,000 hour life! Thats GREAT!!!



Mark

The factory regulator has built in temp compensation that protects the factory alternator... The problem with some external regulators, on a Hitachi, is that you lose the protective feature that babies the alternator. If converting a Hitachi reg to external it should ideally use dynamic temp compensation (finds the "sweet spot" for max performance) or have the ability to limit the field potential in the programming regulator....

[MarkJ]

Originally Posted by hellosailor

So you get what, a tenth of the expected median lifetime? Without the need to replace those pesky mechanical bearings and contacts? Or did they wear out first, as expected?

Bearings feel fine.
I think its the bushes so will get them replaced.

Its wasn't a sheltered life the dang boat was a Sunsail boat! Wanna look at a few threads about how people treat charter boats!

But I treat the engine well. Never over 2,200 RPM when the max is 3,500 rpm.

Compared to when we were kids with our first cars alternators could be expected to last 2 years or so. There was an auto electrician on every corner.... Now where are they?



@Main Sail, I didnt know that. Thanks for the info. Mines internally regulated, anyway, but have always wondered about getting an ext reg. but its never been a real drama.

Mark

[Meck]

This is post from Rick several years old and a link to the entire thread is at the end of the article.

I would really like to find someone who has actually done the modification on a Hitachi/Yanmar alternator.

I have two specific questions to anyone who really knows;

1. IF (and I mean if, because one report I read did not mention removing the diode pack, while Rick stated that it must be removed) the diode pack is removed, where do you connect your positive battery charge cable? The positive charge cable comes off of the diode pack on the Hitachi. The smart regulator has a positive sense wire, but I don't think you run your charge current through the regulator??

2. When connecting the new field lines from the brushes, do you simply by pass the internal regulator. I did this and then tested the two lines coming off of the brushes and there was no measurable current coming off either brush.

Converting your alternator to an external regulator
The Hitachi alternators on the Yanmar engines are good ones when converted to be controlled by an external regulator. If you can get the 80A unit which will put out over 90A with an external regulator.

If you can still find them the Incharge (or Alpha) regulators sold by WestMarine are the easiest to install and use. If you use a Balmar regulator the best one (in my opinion) is naturally the most expensive. All of the Balmar regulators are a pain in the ass to set up from any default setting.

Here are some instructions that you might find useful if you choose to convert your alternator yourself:


SUBJECT: Converting an internally regulated, or "N" field alternator to "P" field external regulation.
These instructions are for converting internally regulated or "N" field alternators into the "P" field externally regulated type allowing them to be regulated by external regulators. Please note that modification must also include removing the diode trio in addition to the modifications listed below. As a result, it is recommended that alternator modifications be performed by a qualified alternator mechanic, with you the customer specifically pointing out the need to disconnect the diode trio from the stator windings. If the diode trio is not disconnected from the stator windings extremely high DC voltages can occur which can damage other electrical equipment. Once disconnected you may choose to leave the trio physically in place.
1. Make a reference mark on the case front and back halves. This is to ensure that the alternator is reassembled with the case halves oriented the way they were before disassembly.
2. Remove the four long bolts that hold the cases halves together. Gently tap and pry the front and back case halves apart. The pulley, shaft and rotor will come away as a unit with the front housing. The laminated steel core and stator windings stay with the back case half.
3. At this point, the spring-loaded brushes should have popped out of the brush holder.
4. Note that there is a hole in the back of the rear housing situated so that you can insert a toothpick or piece of wire to hold the brushes compressed in the holder during re-assembly. Use this process later during re-assembly.
5. The goal of this next operation is to end up with one brush directly connected to ground and the other brush connected only to a wire which will be routed outside of the alternator case.
A. First the negative brush: With an ohmmeter or continuity tester, check to see if one brush is already in direct connection with ground. On most alternators, the case is the ground. Others will have a ground stud isolated from the case. In both situations the resistance between the brush and ground should be very near zero. If neither brush is grounded, select one of the brushes and solder a jumper wire onto the brush lead and connect the jumper to ground.
B. The other brush must be disconnected from whatever it is presently connected to, and soldered to a length of wire. This wire should be labeled "Field" or "F", and routed outside of the alternator case.
Pay special attention to maintaining insulation and clearance from wires rubbing on moving parts. Use a tie-wrap to secure the "F" wire where it exits the alternator case.
6. This is a good time to buff the tarnish off the slip rings where the brushes ride.
7. Re-assemble the brushes in the holder, spring first, brush on top, ensuring the brushes can slide freely in their slots.
8. Now use the toothpick or piece of wire (unbent paper clip) to hold the rear most brush while loading the other brush and spring. Advance the toothpick or wire to hold down the last brush and spring.
9. Re-assemble the case front and back halves ensuring the reference marks made in step 1 are aligned.
10. Insert and firmly fasten the four long case bolts tightening them evenly.
10A. Rotate the shaft and note that the pulley runs true and that there is no scraping noise from inside the alternator. If there is, discover the source before continuing...may have to take apart and check the alignment while reassembling.
11. Pull out the toothpick. You will hear a click-click as the two brushes snap down on the slip rings.

11A. Rotate the shaft and note that there may be some slight noise from the brushes against the slip rings...this is normal as long as it is relatively slight.

Entire Thread:

http://www.cruisersforum.com/forums/...ator-7620.html

One more good report, but leaves my questions unanswered:

Alternator Modifications for a Digital Regulator - myHanse - Hanse Yachts Owners Forum - Page 1

[hellosailor]

Mark, those auto electricians (starter and alternator motor shops) on every corner usually were the reason the alternators didn't last long. A lot of filthy shops, sloppy work, and then they'd spray it all shiny silver when they were done. Which looked nice, but that one coat of silver paint on the diodes was enough to make them overheat and fail. (According to Delco directly.) Good for return business, not so good for road trips. Coming back on topic...

Meck-
The diode frame, or diode rack, or whatever one chooses to call it, is the place where the AC from an alternator "becomes" DC and gets put out to the electrical system. I don't know what you mean by "remove" the diodes. You may need to remove ther ack to access something. You could certainly remove it and replace it with an external set (never heard of that) or a more robust set (frequently available) but if you simply "remove" the diode frame, that's like removing the mast from your boat. Sails ain't gonna work so good without it.(G)

[Maine Sail]

Your don't remove the diode rack and leave it out, won't work at all if you do that. The diode rack on some is in front of the regulator, depending upon how yours comes apart, so in order to wire it you often need to unsolder the stator leads then re-solder it back together..... If you can slide the rear bearings out and pull the front case and rotor out you can get access easier but it is a bit tough working inside the stator...

[FlyingCloud1937]

The Hitachi, like all claw pole alternators is a simple 3-phase device. It may have two rectifiers...in the case of a self excite alternator.

The big rectifier/diode rack/pack is connected to the stator, and is the charge source into the bats.

The second/smaller, if self excited is the diode-trio, it is also connected to the 3-phase stator. It's job is not to charge the batteries. But to provide the dc voltage for self excitation, as well as dc current for the field windings.

So when converting to an external regulator, you don't need the diode-trio, because the excitation circuit as well as the current for the field is provided by the bats. and through the regulator.

Leaving the stock regulator in-line with the external field wires, may or may not work. Depending on if it is a hi or low/P-type/N-type.

But what leaving it in will do is convert your three stage into a 2 stage. Because the internal will overcome the float voltage mode. Not a problem unless you motor for hours on end with a full battery.

If you plan to do the conversion youur self. Don't just bring out the field wires through any hole available. Drill and use isolated studs. Else the wires will soon be shorting to the case and will not only fry your internal regulator/Diode-Trio, but also your external regulator.

Lloyd