the battery should be 12.8V or above without a charger on it.

14V is the charger, I bet it's not 14V when cranking.

What does the voltage drop to when it cranks, without the charger on it?

That will tell where your battery is.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.