Parasitic Drain?

[rotorwrench]

A 6-volt lead/acid battery will have a higher voltage reading right after a full charge but will lose a tenth of a volt after it sets a while. This is normal from my experience.

The newer the battery, the less it will drop off. As long as it's above 6-volts, it should start the car but condition largely depend on how long it has been in service and how often it is used.