Lightweight Lithium car batteries

The NAPA battery in my red Charger is in the trunk. It isn't that old but it won't charge over 12.4 volts. It drops to 12.2 in a week or so.

Btry 1.jpg

At 12.4 it is already at 80%, when it drops to 12.2 it is at 60%.
A buddy has had his 68 Dart here for 3 weeks and his Interstate tested at 12.66 today. It is almost 5 years old, easily double what my NAPA battery is.