Also there's more to really testing a battery than sticking a voltmeter on it. To really know it's condition it needs to be load tested, to mimic starting a car.

 

Yep, you have to sock the sherbert to it. A poor battery will read good volts with no or very minimal load, or when charging. But when you put a real load on it the voltage drops like a stone, engine won't crank, solenoid may not even pull in.

Also the best known way to make a computer server room very quiet ...lol

The knowledge of how to operate the testers at the auto parts stores vary greatly, as do the software options for particular testers. Sorry they missed it.