Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-l] cars and physics



John Denker said: "Given that even in a 6V system it was possible to provide enough juice to the starter motor, do you really think they were motivated to switch to 12V because that was the only way to get enough juice to the ignition circuit? That seems implausible, with several orders of magnitude to spare."

But in an earlier post John also said: "I reckon the real driving force was the fact that at higher voltage you can transport more power using thinner wires. As cars come to have more and more electrical stuff, this becomes more and more of an issue. At constant power, as the voltage goes up you need less copper but more insulation. Insulation nowadays is very cheap, very light, and very good. Copper is heavy and expensive."

I find this explanation implausible because the change from 6 volts to 12 volts occurred in about 1953. Cars in 1953 had very little of the "electrical stuff" that is the norm today. Aside from the stuff under the hood and the lights, you had an AM radio, a heater fan, and a cigarette lighter. Perhaps the starter was the primary impetus for the change. The higher compression engines, especially with eight cylinders and approaching 500 cubic inches, would be much harder to turn over than a lower compression six cylinder. Aside from higher performance engines, there wasn't much else changing in 1953 that I am aware of. It seems a 6-volt to 12-volt change in 1953 would have to be related to the engine. If not the ignition, then the starter.

Michael D. Edmiston, PhD.
Professor of Chemistry and Physics
Chair, Division of Natural and Applied Sciences
Bluffton University
Bluffton, OH 45817
Office 419-358-3270
Cell 419-230-9657