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