Cluster gauge question

Hi,

So I have noticed lately that almost every time I start the car my cluster gauges run through a self test, does anyone else have this issue or know about it?

It am wondering if it might be the battery. I tested it and the charge voltage is around 13V which is normal but when i turn the car off the battery voltage drops to just under 12 Volts which is not so normal.

Any comments are welcome.

Thx