Voltage Regulation, Re: 1959 Starflite

[frankr]

And that’s the whole point. A load OR a low battery can draw more than ten amps causing overheating of the generator. The correct regulator limits the current to ten A.

[mogems-yahoo-com]

Thanks Guys! If anybody comes up with a Part No. and/or place to buy it that would be great. For now I’m going to lend him my reg. from my 1973 Sportster.

[jeff-register]

Wow, I sure would like to have a K model Sportster!! In 73 Harley was still using a dc generator? That’s crude not to swap to a brushless AC generator. My 54 Duo-Glide has a three brush 6 volt three brush genny. No E-start on this one!!
Can someone explain the differences in the A & B Gennies? Please!

[rvpapasso]

JP Cycles has a 12V, 10A regulator that should work with your OMC generator. I bought one and bench tested it with a Prestolite 4008M generator and 3A load plus battery. The test showed the solid state voltage regulator kept the voltage around 14.5 volts and was constant as the load was turned on and off as well as disconnecting the battery:

http://www.jpcycles.com

P/N 381-309
$44.99

When I put a generator on my 1960 40Hp Johnson I bought a mechanical regulator and was VERY unhappy with it! It would not stay in regulation, sometimes not charging and sometimes +16V. At that time I did not know about the Harley regulator and bought a solid state regulator from a company called Jimcotest that was for a 12V, 10A generator. I never had a problem in over 10 years! However Jimcotest stopped making solid state voltage regulators for generators. That is why I bench tested the regulator from JP cycles just in case I need a spare.

One thing to be aware of when using a solid state regulator is the generator output will require a slightly higher RPM than when using a mechanical regulator. A mechanical regulator holds the field to hard ground at low RPMs. As soon as the generator starts spinning it is building up voltage until the terminal voltage is reached.

A solid state regulator uses a transistor to ground the field and thus requires a slightly higher RPM to get enough current thru the field to excite the transistor to turn on and ground the field. There is also approximately a 2V drop across the transistor which does not allow full generator voltage across the field at low RPMs. I have no idea what RPM this is and I would suspect you will not even notice this subtle difference.

My boat is a heavy 1960 16’ MFG and I have a voltmeter and ammeter on the dash. The only measure I have is that at a slightly higher RPM that would make you a little uncomfortable in a no-wake zone the generator output is up to 14.5V. Since I don’t have a tach I can’t tell you the RPM at that speed. However at cruise RPM up it works great! I highly recommend not even fooling around with a mechanical voltage regulator.

I did not mount my regulator in the solenoid box and chose to mount it under the rear seat and wire it back to the solenoid box. This way it would have adequate air around it for cooling plus be out of the way. The solid state voltage regulators are a sealed unit so there is no concern about them being exposed to the high humidity environment. Just make all your wiring connections soldered or sealed with heat shrink.

Just a little more information……

OMC always used what is called a 3 unit mechanical regulator:

– One unit isolates the battery from the generator so the battery does not discharge into the generator at low RPMs
– One unit controls the voltage regulation
– One unit current limits the generator output to 10 amps to protect the generator. A condition that would be encountered typically with a partially or dead battery.

Some people in the day would use a voltage regulator from a car. This would work fine except car generators were typically 30 or 40 amps. The unit that protects the generator is set to 30 or 40 amps and would provide no protection for a 10 amp generator.

Mechanical regulators also use metal contacts for all the functions. It is also a careful balance of spring pressure, magnetic forces, etc., to work properly. Contacts eventually pit and need cleaning and tension adjustments on the springs need tweaking periodically. In their day it was all they had and it worked provided you did the periodic maintenance.

Dollar for dollar and reliability you can’t beat a solid state voltage regulator.

One more thing, you still need to “flash” the generator if it has been idle for a while and always good practice when installing a new regulator. If you don’t know what that is or why just ask.

[rvpapasso]

An “A” generator has the field internally connected the armature output. The “B” generator has the field connected internally to ground. The voltage regulator for an “A” generator controls the generator output by bringing the field to ground or letting it float. The regulator for the “B” generator controls the generator output by connecting the field to the battery or letting it float. Most solid state voltage regulators are designed for an “A” type generator.

With regards to the ’54 Duo-glide…….

I thought the Duo-Glide did not come out until 1958. Wasn’t the ’54 the “hydra-glide”?

I have a 1943 WLA that uses a 3 Brush 32E. I added extra bullet lights to the rear and spots up front. The 32E as a 3 brush can’t keep up with the load since it is an unregulated generator with a very narrow peak range, falls off on either side with only one RPM producing max output. The 32E as a 3 brush is really an unregulated current generator that depends on the health of the battery to regulate the voltage. The battery must be able to handle excess current when it is fully charged which in turn becomes heat and boils the electrolyte in the battery. Hence never use a sealed battery with a 3 brush generator! One a good day at peak it is maybe a 10A generator over the narrow RPM range. Very hard on batteries since it is unregulated but in its day for the minimal job it was designed to do it worked.

I came up with a trick sh*t way of converting it to a regulated 2 brush without changing any of the field wires. This will gaurentee a stable output of ~7.2V across all RPM ranges and loads. Plus it will not cook a battery due to overcharging as the 3 brush 32E will do.

Let me know if you are interested. After the simple conversion you must still treat it as a stock 32E and not try to charge a dead battery and limit your load to 10A. If you exceed 10A whether it is left as a 3 brush or converted to 2 brush operation it will overheat and throw solder off the armature wires.

[chris-p]

As Frank stated, it must be a 10 amp, A type. I have bought the one from JP cycle as well, and works well. Also bought one from ebay which worked. Just really need to find a way to mount it.

RV, thanks for all the great info! Was the part number not 381 329? Maybe my memory sucks! You are probably right but I think the 381309 is a 22 amp model.

[rvpapasso]

The correct JP Cycle part number is 381-309 which is for the Harley generator, 12V, type “A” field, 10A generator. P/N 381-329 is a voltage rectifier/voltage regulator for the mid 70’s/80’s Harley alternator equipped models, the so called “cone shovel heads”. P/N 381-329 will not work with a gnerator.

[legendre]

quote FrankR:

And that’s the whole point. A load OR a low battery can draw more than ten amps causing overheating of the generator. The correct regulator limits the current to ten A.

So then, did the original mechanical reg. have a current limiter? Honest question, I’ve never worked with older HD bikes.

If memory serves, smaller cycle-type regulators (Lucas, Bosch, etc.) didn’t have current limiting – they’re the simple two-coil type, one cutout and one regulator. They weren’t known for burning up armatures.

Another question, while we’re at it – at what speed is the OPs gen. driven? Cycles typically drive the gen. at crank speed, while automotive applications drive the alternator / gen. at about 2X crank speed. What’s the ratio for this OBM system?

quote RVPapasso:

The correct JP Cycle part number is 381-309 which is for the Harley generator, 12V, type “A” field, 10A generator. P/N 381-329 is a voltage rectifier/voltage regulator for the mid 70’s/80’s Harley alternator equipped models, the so called “cone shovel heads”. P/N 381-329 will not work with a generator.

This is absolutely correct, #381-309 is the one you’d want.. Price is better than the Podtronics as well. However, I don’t see any current specs for it.. does anyone else have that info?

ETA: Just noticed this..

quote RVPapasso:

OMC always used what is called a 3 unit mechanical regulator:

– One unit isolates the battery from the generator so the battery does not discharge into the generator at low RPMs
– One unit controls the voltage regulation
– One unit current limits the generator output to 10 amps to protect the generator. A condition that would be encountered typically with a partially or dead battery.

Ok, so the OMC +did+ have a current reg – that’s surprising to me. But does the HD reg you’re suggesting also have the current reg coil?

[rvpapasso]

I have never seen a 12v mechanical regulator that did not have a current limiting unit. As far as I can determine all the OMC 12v generator mechanical regulators were 3 unit with current regulating.

With regards to Harley, the answer is yes and no with regards to including a current limiter. Typically the 6V regulators were 2 unit, cutout and regulator. Because the demand on the battery was low due to lack of electric starting, the battery, if well maintained, would not get deeply discharged in normal use.

In 1965 Harley introduced 12V to run their first electric starter on the big twin. Since electric starters can discharge a battery in a short time of cranking all the 12V mechanical regulators were 3 unit to include current limiting to protect the generator since the battery after cranking is going to suck a lot of current to be replenished.

The voltage regulator sold by JP cycles is actually made by Cycle Electric, model CE 102. It is designed for the Harley model 65 generator. This is a 12V, 10A generator. Harley had a great way to identify the year parts were first introduced by including the year in the part number. The previously generator mentioned, 32E, was first introduced in 1932, 5th revision. The model 65 generator came out in 1965, same year as 12V systems were introduced for their first electric starter also introduced in 1965.

All Harley generators run faster than the crank speed due to gearing between the crank and the generator gear. The only motorcycle I can remember that had the generator running at crank speed is the 70’s Yamaha 125. The generator was mounted directly at the end of the crank. It was unique that the generator also doubled as a starter. By mounting it directly to the crank eliminated the problem of generator belts, drive gears and over run starter engagement mechanisms.

I never counted the flywheel teeth on my 1960 40Hp Johnson or the generator pulley to determine the ratio. However the generator is spun faster than the crank.

For a generators getting the RPM right for all crank speeds is an interesting science. Too slow and the generator doesn’t put out anything useful. Too fast and the magnetic field starts to warp where it only passes thru part of the armature decreasing output and causing all the current to run through less windings, I.e. Heating up the armature. This is why most generators are designed to work at high RPMs and not at low RPMs since most driving is above idle. If the ratio was changed to spin the generator fast for low RPMs then at higher RPMs the generator output would decrease or burn out the armature due to the magnetic field warping.

Alternators do not have this problem due to spinning the field instead of an armature. That is why car alternators put out useful voltage at idle and also at high RPMs. No matter how much the magnetic field warps there is always a stator coil to pick it up.

Sorry for the detour from topic.

[legendre]

quote RVPapasso:

I have never seen a 12v mechanical regulator that did not have a current limiting unit. As far as I can determine all the OMC 12v generator mechanical regulators were 3 unit with current regulating.

Very good, thank you. I’ll admit I’m surprised that these are 12V systems. I mean, it’s good that they are, but I didn’t expect it for some reason..

quote :

(…) since the battery after cranking is going to suck a lot of current to be replenished.

"On a Harley.." 😉

Kidding but not.. no offense, either way.

quote :

All Harley generators run faster than the crank speed due to gearing between the crank and the generator gear. The only motorcycle I can remember that had the generator running at crank speed is the 70’s Yamaha 125.

My experience, with gens. on British bikes, is that they run at crank speed. For example, 50’s Triumph T-bird driven off the exhaust cam (running half-speed), but with a pinion gear the same size as the crank pinion. Same for 50s to early 70s BMW and Guzzi, I believe, though at lest the Guzzi run belts.

quote :

I never counted the flywheel teeth on my 1960 40Hp Johnson or the generator pulley to determine the ratio. However the generator is spun faster than the crank.

Teeth.. these OMCs run toothed belts? Really?

quote :

For a generators getting the RPM right for all crank speeds is an interesting science (…) Sorry for the detour from topic.

Can’t speak for the others, but no need to apologize to me – I’m quite interested in everything you’ve written. Very informative and clearly presented. And yes, alternators are superior in every way – particularly when fitted with modern rectifiers and regulators. Hard to believe the industry had to cope with inefficient DC generators for so many years, all for the lack of a compact and efficient solid-state rectifier! They’re so cheap & common today, it’s the sort of thing everyone just takes for granted.

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