94 Grand AM Battery / Computer Problems ??

Hi,
I have a V6 94 Grand AM GT.
Since replacing the battery, which was purchased at Autozone after giving specifications of the car, strange things have been happening...

The clock on the radio no longer keeps the correct time, it will run slow.
This was the only problem for a month or two but then the radio display would be jumbled after starting the car and the radio not work.

Today things got worse....
When the headlights were switched on the interior lights would keep coming on and off and the door locks constantly clicking.
ABS, airbag and brake lights would also be on, though brakes worked fine and again a jumbled display on the radio.

If the car is run for a while, switched off and restarted, all comes ok. Until the next time it is left over night.

With the ignition on but car not running, the voltmeter shows around 10.5V. Once running around 13-14V.

Is the battery at fault, not holding and providing enough charge and causing the computer to crash ??
or is this something else that is causing the problem ?

Thanks in advance.
Tuney.

First, check the battery leads. The problem you are describing indicates a loss of power. If the leads are bad or are not making good contact the alternator will not maintain the battery and it will show low voltage prior to starting. When you are running you are getting voltage at the terminals but it may not be going into the battery. Second, it is possible that the new battery is bad but I would recharge it and check the battery cables. If it fails to hold a charge after that take the battery back and get a new one.