Originally Posted by kg6mti
It could still be your battery. If your battery isn't putting out enough amperage then it won't be able to start your engine. It is possible for the battery to display full or near full voltage but low amperage. I would recommend getting the battery tested. But your problem could also be your starter or the solenoid. Any good auto parts store should be able to test all these parts for you but you will have to remove them.
What he said. A voltmeter is effectively useless at testing batteries (automotive or otherwise) unless it can put a load on it.
Most national chain auto parts stores (AutoZone, Advance Auto Parts, Pep Boys, etc) will test your battery, starter, and alternator for free. Go to one of those places and see what comes up, I bet it's a bad battery.
Not for nothing, but the terminal connectors are tight on the battery, right?