Are you testing the battery at the battery terminals, or through one of the accessory ports? If you are doing it through an accessory port, you are just testing the output of the DC to DC converter (which is pulling power from the HV battery pack), not the 12 v battery. With the car off, as soon as you open a door, the DC/DC converter goes on to power accessories, like door locks, and the ports at around 12 volts - but that power is coming from the HV battery pack, through the converter. The 14 volts you are seeing when the car is on, is the output of the DC/DC converter at full on, with 12 v battery charging enabled.
If you are testing via one of the power ports, try testing through the rear cargo area port.
First, leave the car off and locked for at least 20 minutes so all the accessory ports power down. Then just open the rear hatch, and test through that rear port. Supposedly opening the rear hatch does not turn on the DC/DC converter, like opening doors does.
Or just hump the battery down to your local auto parts store and have it tested.
Some of the errors also could point to a bad DSC control unit.
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