It sounds like I'm the absence of a generator, a T can run perfectly fine off the magneto. So is the only purpose of the generator to simply recharge the battery after it is used for starting?
A two fold answer....
1- yes, the generator can be used to charge the battery AND run 6 volt lamps at rated illumination. A simple lantern battery can be used for the feed to the 'batt' side of the coilbox switch and will last about a year if used for starting only (then running the coils on magneto after)
2- A car without a generator must use the magneto voltage for lamps. Since the magneto output is generally from 6-30 volts...there is actually a problem. The light illumination changes with the RPM of the engine...and...lamps can only tolerate about 20% of over-voltage before they just go 'pop'
So when was a generator introduced? I assumed it was when starters were introduced. But I know, for example, 1915-16 used electric lights but no starter. Did they have generators?
1919 with the electric start. 1915 & up used magneto powered head lights.
So basically from 1915-1919 the headlight brightness depended on engine tons. With a generator installed starting in 1919, the lights were able to maintain a consistent level of brightness independent of engine rpm.
Bingo...you got it
The wiring diagram you posted as being for 1915-1919 should be labeled as 1915-1916. Starting nominally in '17 the horn button at the top of the steering column became a "combo" light switch and horn button. There was no longer the dash mounted light switch. This same year Ford also began to use a "light dimmer" coil mounted to the motor side of the dash which then allowed a bright and dim voltage for the lights derived from the magneto. Finally also this same time the magneto horn was wired with only one "hot" connection and the other connection to the horn being a ground through its mounting bracket and horn metal housing. The wiring up to the combo button was a magneto feed for power that was connected to the "horn wire" when the button was pushed. The horn wire came down to the horn and went to its "hot" lead connection. The magneto feed wire was then also connected via the comb switch to either a "bright" or "Dim" feed wire which came down to the dimmer coil which has a 3 terminal connection with brite and dim wires going to corresponding brite and dim winding connection with a 3rd common dimmer coil wire then providing power to the headlights. The dimmer coil was a single winding device with taps at both ends and another then in between the ends.
If someone tries to wire up their '17 or later car with the above diagram they are going to be pulling their hair out.
I hope this helps.
Some view the variable intensity of the lights as some big 'negative'. I view it as just another one of those things that makes a T a T.
I'd edit my post if I could.
Steve brings up a good point....why can't we edit?
The light switch on the dash was used through the end of the 1917 model year.
The diagram above is correct for 1917 Model T Fords.
When I was 15 or so I had some aftermarket headlights with 12 volt sealed beams. I didn't know about the mag being AC, variable voltage, I might have not even known the difference between AC and DC. I ran a wire from the mag post to a switch then to the lights. I drove at night one time. I went to a lock-in at the baptist church about a mile from my grandmas house, where I live now. About the time to get locked in I left. They worked for a mile like that. Now that I live here that is my test run drive, to the church and back. Not to hijack the thread but I remember going to there with my grandma one day, no body, sitting on the gas tank, no floorboards and it died. My grandma told me to "take that little thing off with the 3 screws holding it on, my brother used to do that" She was right, mag post was dirty. I had chunks of babbit flying off the rods and around inside back then. Wasn't a forum in 93.
Erik is correct. I can't even read my own notes. Ford removed the hole in the dash for the light switch in October of 1917. I had it wrong in my notes as being removed in 1916 on the same day.
The first wiring diagram, labeled "1919-1927", is actually for 1922-1927 cars. The 1919-1921 Model T's with starters and generators had magneto horns, so the diagram is different.
Steve and Rick,
You can edit your posting. But you have to do it within about 5 minutes of posting it. After that the option to edit the posting goes away.
One way to get there is to log into your profile. Go down to the "Recent Posts" and it will have a "yellow pencil" under "edit". Click on that and it will let you make changes. But after about 4 to 5 minutes it will no longer allow you to make the change.
I just edited this posting. I was going to add a screen shot, but I don't see the option to upload a photo. I'll have to post that later.
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(Message edited by hap_tucker on February 13, 2017)
And the photo of the edit pencil:
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Also, thanks for all the great information on the wiring.
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Most general aviation aircraft (think small single engine) still use magnetos to power the spark plugs. Similar to the Model T they use the a generator to charge the battery that powers the lights, radio, navigation, and starter etc. There are a lot of differences from the T [the T is a low tension magneto the general aviation magnetos are normally high tension, the T has a single spark plug per cylinder while most of the general aviation engines have two spark plugs per cylinder etc.) but the option that the engine can be run without a battery is true for both the T and the general aviation aircraft. And like the T the earlier general aviation air craft did not have an electrical starter. That added additional weight to the plane and cost.
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Yes, I've edited several posts. But usually, as in this case, I don't notice the mistake until after the brief editing opportunity has expired. That's the cost of using this obsolete software most of us prefer.