Electrical question 1929 Graham-Paige

[Graham Man]

I have a 1929 Graham-Paige it is running great... here is the issue.  When the lights are turned on it begins to loose power, it will hold it's speed but not accelerate.  Shut the lights off and it takes right off again.  Mechanical fuel pump, all 6 volt original car.  New condenser last fall, it had a miss, the miss is gone.  I ran a completely separate electrical circuit with relay for my Trippe lights, same effect when the Trippe light are on.  I do not drive it after dark for the most part so far it is just annoying.

 

Thought one weak battery, it looks like it is charging well.  Have not switched it out yet

 

Second:  bad coil?  Have not switched it out yet 

 

Any other ideas?  I have not checked the dwell, or points lately

[edinmass]

Battery was my first thought. While voltage may still be ok, sulfated plates may be causing problems after the system starts charging it and the battery warms up from charging. I have seen this in the past, and it was almost common. Now Optima and gell batteries almost eliminates the issue in stock performance cars. Running top fuel at the drag strip the modern batteries often cause lots of problems as large demand and draw down causes unstable voltage.........want to know how many motors went boom before we figured that one out?

Edited May 28, 2020 by edinmass (see edit history)

[Bloo]

Look for a bad connection somewhere between the cutout (or regulator), which is the "hottest" point in the car. and the headlight switch or ignition switch. I cant really call it any closer than that without a wiring diagram.

 

What I suspect is happening is the lights are drawing the voltage down (because of a bad connection), and anything that comes after (like the ignition switch) is also getting low voltage.

 

It is also possible that your charging system is just not keeping up. It should manage the headlights ok, I would have my doubts about the Trippe's. I think they're 25 watt bulbs, so the pair probably draws over 7 amps all by themselves.

 

Check the voltage at the ignition coil, and then switch the headlights on and see how much it changes. Preferably do it with the engine spinning fast enough that the generator is cut in.

Edited May 28, 2020 by Bloo (see edit history)

[Graham Man]

I picked up a new battery, I will clean up the connections and give it a try today... after the rain stops.   I will also clean up the cutout connections.

 

Thanks again for the help

[edinmass]

Be sure to charge the battery before you put it in the car. A generator is Ade to top off a battery, not charge it up from half. 

[Graham Man]

Thanks for the tip, it is on the charger now.

[DFeeney]

Hello,  Just to cover all bases I would take the generator to a shop to see what it's output is. My local shop does it for free.The more information you have will help in solving your problem.