1957 ammeter gauge flutter

[Ray B.]

I've searched for other post on this subject but not helpful. My 1957 Ammeter gauge goes bats when I start the car or put a drain on the battery (say turning on lights) but then starts to settle down. In the meantime the needle almost pegs in both extremes. I've checked the voltage on the battery as well as made sure all connections are good. I am going to buy a replacement voltage regulator just to see if it possibly the VR. I have always pretty much ignored the gauge thinking thats how it works but after reading the NCRS judging manual I think there is an issue.

Any ideas would be greatly appreciated.

[Ray B.]

Just to add a little more info. the battery is a reproduction of a 2SMR53 it has an agm battery inside. its about two years old. But i have the same issue with a brand new battery installed as well
Cold the battery is 12.67
start its 13.49 but during warm up runs up to 14.00
at idle it is 13.91
lights on it drops to 13.22 but the ammeter stays near zero with no crazy bounce
parking lights on it is 13.4 but the ammeter bounces
at shut off after 5 minutes it is down to 13.12
leaving the voltage meter on it I do see some crazy vacillations though it may go from 13.9 down to 13.11 quickly then back up to 13.89 with nothing else being turned on or off