Answer No. 85 on Magneto lights

[Mark Nunn]

I was reading the 1914 Operator's Manual and was surprised to see this answer. This is not mentioned in the 1913 or 1915 manuals. I believed that the electric headlights received current from the magneto. What did Mr. Ford suggest to operate lights in the Model T?

14 MAG LIGHT.gif (32 KiB) Viewed 2431 times

[Rich Eagle]

Thanks Mark. I blew out 4 magneto bulbs the first night I tried to drive by them. At high revolution the mag provided too much voltage. We drove by kerosene lights 30 miles pulling over each time we saw a car. I haven't used them since. I suppose there are some good remedies but I lost interest. ( 4 of us in a '15 Runabout)
Rich

[Erik Johnson]

1914 Model Ts were equipped with acetylene lights and a generator on the running board. That answers your question on how the headlights were operated.

[Scott_Conger]

And to add to Eric's response, 1915 was the first year of thicker magnets and oval coil windings, creating a more powerful magneto overall.

See the Valley (same as St. Louis) Magneto-meter dial...the 1915 output was a good deal higher to support the use of lights...

http://www.mtfca.com/discus/messages/80257/115454.html

[Mark Nunn]

This is from the encyclopedia in the 1914 section. The changes seem to be transitional into the 1915 model year.

MAGNETO
Late in the 1914 model year the magneto was enlarged
and the magnets were now 3/4-inch thick. This change
began with 572,437 on September 4, 1914, and by October
(after 598,041) all engines had the new magneto. The
new magneto was needed to supply power for the electric
headlamps used on the then-new closed cars, introduced
in the fall of 1914. (While the Sedan and Coupelet were
introduced in 1914, they are considered to be 1915 cars and
are not a part of this coverage.) The Touring and Runabouts
continued in the 1914 pattern until about February 1915,
when the 1915 style began to be produced at the Highland
Park plant.

HEADLAMPS
It is believed that all 1914-style open cars used gas
headlamps but it is quite possible the later ones came with
electric lamps. In a letter to the branches, dated January 12,
1915, Ford noted that they were no longer supplying the
gas lamp tube on the radiators “as all cars now have electric
lights.” (A tube, part number T-4052X, was listed for use
when the new radiator was used to replace the older type on
a gas-lamp car.) Yet it was not until February 1915 that the
1915 style car bodies were being shipped to the branches.
Therefore, one would think that 1914 bodies built until
about March or April came with electric lights. On the
other hand, we have seen a number of pictures of 1915-
style Tourings (old pictures of seemingly original cars)
with gas lamps. Ford never admitted to using gas lamps on
a “1915” and it is possible that owners, unhappy with the
poor electric lights, replaced them with the older gas type.

[Steve Jelf]

Even with the improved 1915 magneto, mag lights are marginal at best. I will drive in town at night because there are street lights which make car lights irrelevant, and I'll drive a familiar country road coming home. But on a strange dark road, especially one with curves, no way. If you go fast enough to make the lights bright enough, you'll outrun them.

After reading of mag bulb burnout being such a problem, I've been surprised at how well they have lasted for me. Yes, they do go eventually, and I carry spares (O'Reilly and Auto zone don't stock them), but in my limited experience they have lasted pretty well.

[Novice]

Ford built and sold a magneto voltage reducer for dimming the headlights on 1915 to 1918 model Ts without a generator and electric starter. they are still found for sale at reasonable prices on e-bay and here on the forum. You can also take a choke coil out of a old radio power supply. or convert a model T coil to a choke transformer and hook it up in series with the magneto and headlights. as the engine rpm increases the frequency of the magneto output along with the voltage increases and the choke coil limits the voltage passing through the choke at the higher engine speeds thus limiting/regulating the voltage to the magneto headlights at high rpms reducing the possibility of burning them out.

[TXGOAT2]

Do you use the T coil's primary as a choke?

[Novice]

Seems like He rewound the coil to get the desired voltage reduction at max rpm. I saw the article some time back but don't remember where.

[TXGOAT2]

Assuming the coil primary is used, a person could use a modern type 6 or 12 volt coil primary, or a number of them in series, to limit voltage at higher speeds.

[Corey Walker]

Isn’t this Ford’s answer to the problem of burning out bulbs? Two wires go to the combination horn button/light switch (bright and dim). They go to separate windings in this dimmer coil then the one wire goes to the wired in series headlights.

[TXGOAT2]

A simple coil (choke) can act as a variable resistance (actually impedance) in a variable frequency AC circuit. For the operating frequncy range of the T magneto, I'd think you'd need an iron cored choke, similar to the primary winding of the T coil. It would be placed in series with the devices, such as lights, that you wanted to provide with regulated voltage/current. The coil's wire gauge and number of turns would affect how much impedance the coil would offer at various AC frequencies.