by Jim Cannon, MAFCA Technical Director
Thirfty Henry Ford would only spend the money to put an ammeter in the Model A if he knew it would help you while driving, so get in the habit of keeping an eye on it.
Here's what to look for and what it can tell you:
- Watch for the ammeter needle to "twitch" as you pop out the ignition switch or turn the ignition switch to the "on" position. This confirms that the coil is getting power. Now start the car.
- After the engine starts and you have it on a fast idle to warm up, check that the ammeter is showing a charge in the battery. If not find out why.
- Look at the ammeter needle when you step on the brakes. It should jump a bit toward discharge (unless you have LED brake lights installed, which draw very little power). It's always good, before you hit today's crazy, busy roads, to know that your brake lights are working.
- If you have a voltage regulator in your generator, or if you have an alterator (which has a voltage regular built in) then you should see the initial battery charge rate on the ammeter steadily drop until it is back to zero in 5 minutes or less. A stock Model A generator will not do this, it has a constant amps output above idle RPM, so you can watch for that while you drive.
- Check the ammeter as you turn your headlights on. The charge rate to the battery should drop with a generator; the needle should jump around a bit but go back to where it was if you are driving with a good alternator.
As you see, the ammeter can help keep you out of trouble every Model A Day!
