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I rarely drive my car at night. But recently I was driving and the dark started to catch up with me. So I put on my headlights and what I noticed was that the ammeter seem to stay at discharge as long as the lights were on. When I cut the lights off it went back to the center. Is this normal? I had my electrical system checked about a year ago (maybe 500 miles since then) by Ross Miller and he said it was fine. I am running an Optima 6v battery
Any thoughts?
My car is a 47 2106.

No, that's not normal and is indicative of a failed charging system.

Or a short in light circuit-should be easy to diagnois

Your battery is "good"!
Two 6V 50/60W headlamps on high draw about 18-20A.
The '47 generator should make ~30A. Unless you were going very slow, it doesn't appear to be charging. I don't have the rpm/output curve handy.
Try to polarize the VR first. If not, Then have someone check the generator.
Sometimes the VR contacts gets "welded" or corroded, from lack of use, on the VR and it won't work. You can take the cover off and inspect.
You might consider going to halogen bulbs later, less amps, more light.

It is the generator that you polarize but it is typically done at the regulator’s terminals so that has called some confusion. There is nothing in a regulator to polarize.

It could be as simple as running a point file over the contacts in the VR. They could have oxidized from sitting.

Robert, you can isolate the problem component by grounding the field terminal. This will bypass the regulator and let you know if it is the generator or regulator that is the problem. Running the engine with the generator field grounded should result in the generator charging full rate. If no charge, then you have a problem with the generator. Don't run this test too long just long enough to see if you are getting charge out of the generator.

Thsnks to all! I will grt onti the disgnosis suggested. Thanks.

I was looking to see if I had the section of the shop manual digital, but not.
I found this it may help or at least interesting period reading. It'll freak a few out as it's titled "generator" but it's about VRs.
You'd have to have the numbers and check against the part list to make sure you have the right stuff on yours.
I'm fairly certain the "P" procedure calls to "polarize" at the VR, so I missed an "at" in my previous post for those who may be confused.
There are different type of generators and the VR must match or you're in for a "ride". That info should be listed on this site somewhere for your model. It's either an Autolite or Delco system.
Don't mix and match.

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Robert, when I owned the car it had Auto Lite generator, starter and distributor. I don't recall the brand of the regulator, but the system worked and charged. I believe Auto Lite for the senior cars and Delco Remo for the juniors.