1990 Audi 200 Charge Problems

Electrical problem
1990 Audi 200

I installed a new alternator on the car but it still isn't charging right. All wires are hooked up. Battery was charged yesterday. The alternator showed good on a bench test. The voltmeter showed good when I took a battery from a different car but now with my re-charged battery it is only showing about 9 when it was showing about 12 with the one out of my other car. Does this sound like a bad battery? Autozone said the battery was good when I took it to them to get tested but something isn't right. Advice please.

Thanks