Factory ammeter

I ran a 10 ga. Wire from the alternator to the post with the black wire on the ammeter. The ring terminal on the red wire had been replaced and looked corroded, so I replaced that also. I solder and heat shrink all the connections.
I ran the new wire, put everything back together and drove the car. The amp gauge stayed between the middle line and full charge line and seem to be charging more the longer I ran it. So I took the battery out and charged it, it was very low, took a few hours to get back to normal. I did put another know good battery in and the amp gauge stayed between the center and + middle charge line, but I was getting 15 volts at the battery. The voltage drop from the alternator to battery is less than 1 volt now. I’m going to put the charged battery back in and see what it does.