Lights work but

[CSPIDY]

Driving with the head lights on I found that the amp meter shows about15 amps discharge, with the lights off it shows about 15 amps charge. Tail lights show about 5 amp discharge.
After about 5 to 10 minutes driving with the head lights on the engine begins to lose power, turn the lights off and the engine runs normal again.
I am running 50/32CP lamps in the head lights.
I have verified there is no resistance in the wires to the head lights and have good grounds.
Could my generator need some help?

[Tom Wesenberg]

Headlights on and engine at fast idle, what is the voltage at the starter switch?

[H. L. Chauvin]

"Could my generator need some help?"

We all have utmost confidence in Mr. Tom W. when generator output problems are mentioned ..... especially thirty (30) amps total difference between when lights are ON or OFF.

[CSPIDY]

I do not doubt his expertise, sorry I haven't replied back yet have been busy with work and play. Can check this at the two wires at the block on the firewall?

[CSPIDY]

Looking at wiring diagram looks like the red wire from the ignition switch goes to the coil, is this where I should take my voltage reading?

[DaWizard]

Ok, with your last statement, something is off. Need pictures of how your wiring is done.

[CSPIDY]

At work today going from memory that is not always dependable. will look at it when I get home this afternoon.

[CSPIDY]

Looking at wiring diagram looks like the red wire from the ignition switch goes to the coil, is this where I should take my voltage reading?

[CSPIDY]

Headlights on and engine at fast idle, what is the voltage at the starter switch?

I had approx 7 VDC at either post of the coil, lights on or off. And a correction to original post with the tail light on it shows 10 amp charge.
had to use an analog swing arm meter the digital meter was all over the place. Is this normal?

[Mitch]

Is this normal?

Yes the Model A secondary ignition with bare wires can play havoc on some digital multi-meters. I'm able to use my more expensive digital fluke meter, it has a smooth button

[Tom Wesenberg]

No need to go to the battery most of the time to get battery voltage. Just read the voltage at the starter switch, as the heavy cable should show no voltage drop.
I'd like to know the voltage at the starter switch with the engine running at 1200 RPM and lights on, then again with lights off. 1200 RPM is just your best guess at speed, or call it fast idle.

I only use my analog volt meter around cars.

[CSPIDY]

I will check this tomorrow afternoon and get back to you

[CSPIDY]

Yes the Model A secondary ignition with bare wires can play havoc on some digital multi-meters. I'm able to use my more expensive digital fluke meter, it has a smooth button

What model Fluke meter do you use? I do have a model 75, will give it a try.

[Mitch]

It’s at the shop so I don’t have the Model # in front of me. It has a smooth feature which allows me to use it on the A

[CSPIDY]

it takes about 5 to 10 minutes for the car to start running rough, the analog meter I am using doesn't have much resolution, there has to be some difference between lights on and off. a digital meter would show that. hopefully my Fluke 75 will work.

[Mitch]

For the record mine is a Fluke 88.

[H. L. Chauvin]

I always lean more towards the analog meter; but ............ positive Model A attitude and continuing to try is always commendable.

Agree 100% ........ if it won't run right ....Fluke It !

[CSPIDY]

No need to go to the battery most of the time to get battery voltage. Just read the voltage at the starter switch, as the heavy cable should show no voltage drop.
I'd like to know the voltage at the starter switch with the engine running at 1200 RPM and lights on, then again with lights off. 1200 RPM is just your best guess at speed, or call it fast idle.

I only use my analog volt meter around cars.

Well the Fluke 75 was no better, used the analog meter and had approx 7.5 vdc with the lights on and 8.5 with lights off when checking at the starter switch. I let run a while with the lights on. This seams a bit high don’t you think? The meter I used has been certified to be accurate. Engine was at a very fast idle.

[Tom Wesenberg]

Yes, that is very high voltage for charging a 6 volt battery. Ideal voltage would be around 7.2, if you had a voltage regulator. A weak battery will have less resistance and will make the generator output show higher voltage. If your battery is good, then put a 6 volt battery charger on it for several hours to be sure it's fully charged, then take the voltage readings again. I like a battery charger of 4, 5, or 6 amps. My Sears 6 amp 6/12 volt is my favorite.

[CSPIDY]

Battery is very strong, will take it for a drive and recheck tomorrow. Will charge it first.

[CSPIDY]

Tom
So after charging the battery took it on a spirited drive, afterwords rechecked the voltage at the “starter switch” and had approx 7.5 and 8 VDC lights on and lights off. I will be getting another volt meter with a better resolution to verify the voltage.
Dave

[H. L. Chauvin]

Hi Dave,

1. Sounds to me like a typical case where the third generator brush was pushed down too far to try to compensate for an "incorrect" and "yet unknown" type of extra heavy electrical draw when lights are "ON".

2. In simple laymen terms, with lights ON and engine begins to die after 5-10 minutes this condition indicates your electrical ignition system is beginning to starve ......... then when lights are turned OFF, generator immediately charges and feeds this starving electrical ignition system.

3. Would be great if, after trying, you would have a close-by Model A club to call for someone to further test and further observe what is going on.

[H. L. Chauvin]

This may sound most parochial, but:

A. It is ..... "known" ..... that the spark at the tips of the spark plugs become weak after 10 minutes of lights "ON" when engine is running and generator is ..... "Charging".

B. What is ..... "un-known" ..... is ..... "the number of minutes" ..... required for the spark at the tips of the spark plugs to become weak ..... "with lights ON" ....... when engine is NOT running and generator is ..... "NOT Charging".

Hmmmmmmmm !

[CSPIDY]

I do have access to some local Model A experts, very good advise. As my quote says.

[CSPIDY]

May have found the additional resistance in my electrical system. The car has had a habit of not starting a few times. I replaced the points and condenser and it seemed to be fixed. But yesterday it would not start again. I pulled the key switch and found It has very high resistance and sometimes an open. I have a new switch and will be replacing it this week. Will advise.
Dave

[Mitch]

Those can drive ya nuts with an intermittent
These are the best available and be sure to insulate the back as stated in this thread further down

https://www.vintagefordforum.com/for...on-switch-info

[H. L. Chauvin]

A typical Model A Forum scenario:

a) A very humble Model A owner/student asks a question.
b) Several Model A owner/Instructors kindly offer all sorts of different answers.
c) The Model A owner/student tries all assumed recommended fixes for the problem.
d) The Model A owner/student returns to report what exactly fixed the problem, whether first recommended or not.
e) The Model A owner/student is now the "Model A Instructor" .... after telling all "Model A Students" exactly what worked.
f) Every Model A owner/student who asks a question and reports the solution is really a great Model A "Instructor".

Dave,

Your initial Model A question is very much appreciated ....... we most humble Model A "students" will be glad to hear from your above reply #13 statement ...... "I have a new switch and will be replacing it this week. Will advise."

Thanks!

[CSPIDY]

May have found the additional resistance in my electrical system. The car has had a habit of not starting a few times. I replaced the points and condenser and it seemed to be fixed. But yesterday it would not start again. I pulled the key switch and found It has very high resistance and sometimes an open. I have a new switch and will be replacing it this week. Will advise.
Dave

My experiance with troubleshooting there is never one path, only many. Sometimes you must try each path till you prove it wrong. This may not fix my light issue but it is a likely solution. That is the fun part.

[H. L. Chauvin]

Appears a Model A is sometimes a lot like a wife ....... a husband tries .... but never knows what path to take ..... agreeable likely solutions are also the fun part.

[CSPIDY]

and I have the bruises to prove it

[CSPIDY]

Well, finally got around to replacing the ignition switch with a new Briggs & Stratton switch, looks identical to the old one except the contact resistance is nil. With the lights on the amp meter is showing about 5 amp discharge and +15 amps with lights off. Is this normal? If not better.

[Tom Wesenberg]

It's normal if you have headlamps that draw 20 amps, which is a lot.
My stock headlamps and taillight draw about 8 amps.