Adjustable DC 1800

[GoldDigger]

181012-2056 EDT

GoldDigger:

By at least 1940 Ford, probably not as early as 1936, was manufacturing a voltage regulator assembly that consisted of three relays. A voltage regulating relay, a current limiting relay, and a cutout relay.

The early story on the voltage regulator is at https://ethw.org/First-Hand:The_Story_of_the_Automobile_Voltage_Regulator

The GE and Ford voltage regulators used an oscillating relay to modulate the average current to the generator field coil. The oscillation frequency would be a function of the mechanical time constants of the voltage relay and the electrical time constants of the generator. Because arcing occurred at the contacts regulator life was a function of contact material and metal transfer. 1000 hours was somewhat of a design goal. Many tests were run on various contact materials to try to improve life. One semester in the early 1940s I worked in my classmate's father's, Emil Zoerlein, electrical engineering lab installing and removing regulators on test stands for life testing. Zoerlein headed up all Ford product engineering testing including the test track, and dynamometer engine testing. He designed the high speed test track at Ford Airport, and developed an environmental hot, cold, and wind tunnel test chamber for a full size car. Later I worked in the radio section of electrical engineering.

This oscillating relay regulator was quite good at voltage regulation, and included temperature compensation.

What manufacturer used the carbon pile regulating means?

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The specific truck I worked on was a 1965 Datsun pickup (first year it was imported and also the last year for that model). It had a 6V electrical system, and in St. Louis winters the starter often pulled the battery voltage low enough that the ignition would not work. The solution was to turn it over a few times to get the gas and oil flowing, then leave the ignition on and go around to the front, stick in the crank and turn it over. Started great at that point!

(Straight four engine with overhead valves with long pushrods, four speed manual transmission with a stump pulling low gear.)

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[gar]

181013-1107 EDT

GoldDigger:

Your Datsun system is interesting. This could have been a design to try to get around the contact life problem of an oscillating relay.

Some wild guesses. Generator 1 kW (certainly this is high 1000/6 = 167 A), maximum field power of 10% at 6 V is a current of 17 A, and a resistance of 0.36 ohms. Probably not a good guess for your dynamo (generator), but it illustrates some ballpark for field resistance, and therefore, where the modulating resistance needs to be. 10% is possibly a poor guess. I need to measure an actual car generator that I have. So further comments have to wait.

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[GoldDigger]

Some engineers, I am sure, prefer a proportional analog solution to a vibrating proportional duty cycle control system. But with the inductance of the field to provide current smoothing the latter is really an elegant solution to eliminate the effect of hysteresis in a simple relay.

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