My 1920 roadster runs pretty well until I put the headlights on. It will run for a bit then while I'm driving it will start to run a little rough, then stall. I only find this to happen when the lights are on. I run off the battery all the time, as I don't have the magneto option ( disconnected ). perhaps a short ? I also noticed the battery runs a little low, as if it is not getting the return.
John,
This used to happen to my speedster before I had my generator rebuilt.
I suspect that your battery does not have enough charge to run both the engine and the lights. Try connecting a seperate battery to the coils, only needs to be a 6v flashlight battery.
I've just been through this scenario myself - the reason was simply that my battery had got to the end of its life after 10 years. As my generator is set to only 5A, and the lights draw about 10A, this means the generator cannot power the lights on its own. The worn out battery was merely smoothing the generator output, rather than providing much of a reserve capacity.
In one instance I was a couple of kilometres from home in the dark, and the voltage must have fallen to about 4 or so. The coils were getting very unhappy, to the point the car stopped. Needless to say, I could hardly see where I was going with headlights so dim. So, I stopped at the side of the road with lights off, and ran the engine at high idle just to charge the battery for a few mins so I could get home.
All quite normal and to be expected with a dying battery.
I'm not saying this is what's wrong in your situation, but just a possibility.
Borrow, beg, or steal a different battery. I'll bet that will cure it!
Cheers
schuh
No electrical expert here, but the generator should put out enough juice to power the lights and coils and still provide a little charge to the battery. At twenty mph the ammeter should show a charge of 8 to 12 amps with the lights off, and a slight charge, just above zero, with the lights on. If it's not doing that the generator needs adjustment or repair.
John B,
I had the same problem and it turned out to be a loose wire going to the ammeter on the dash. Take a look and make sure all wires to the ammeter and switch are good and tight.
Orlando
You need to set the generator to where the ammeter needle is at zero with the lights on. That will charge too much with the lights off. You might need to get a voltage regulator if you plan to drive both at night and also in the daytime.
Norm
Provided the car has a decent battery, the generator does not need to be set for zero charge with the lights on (thus boiling the electrolyte when they're turned off).
The correct size 6V battery has a capacity of about 100Ah. In theory, this will run headlights drawing 10A for 10 hours with no charging. In practice because the battery is not perfect, it will be a little less. No one I know drives a Model T for more than a few hours at night.
Setting the 3rd brush for 5A is a satisfactory compromise and does not damage the battery.
John,
Try setting the 3rd brush for more amps at night and then back to normal during the day. Once you figure out where to set the 3rd brush, you could mark the locations.
Get a solid state regulator from John Regan and it'll take care of itself.......
I think the Old Girl is afraid to drive in the dark!
Many of us will go through this as we get older so why not the old Girl as well.
I think it is most likely an old battery also but it does remind me of a problem I had a few years ago. I was on my way diving to a tour in Canada trying to make up some time I found myself needing headlights. So Iurnned them on only to find the car would die, switching them back off the car would run again. I was in a panic becouse my thought was the gen. not working and the dist. points were needing all the juice to run (yes I wished it still had a mag at that point) I was 500mi from home and still 60mi from the hotel! the last car I saw on the road was a half hour ago and no cell sirvice. Having no choise but to keep driving I did make it to the hotel that night in the dark with no lights. It was frightening. The next morning I found the problem. It was a bare headlight wire causing a dead short. Just a thought. good luck.
Don't overlook ALL the connections on the terminal block.
My '20 coupe got to starting hard.
In anticipation of replacing the cruddy old terminal block I had a new one on hand and finally put it on only about two weeks ago.
End of problem.......