Checking the condition of your battery with a voltmeter is not an accurate test of your battery's condition. To check with a voltmeter correctly : put the meter on the battery. If it reads 12.2 volts (or above), it should be capable of starting the engine. If it drops to less than 9.0 volts when you crank the engine, it's failed and needs replacing. In your case, if it's dropping to around 11.0 volts when you turn the key, I suspect a starter motor fault, or a bad electrical connection somewhere. Start with your battery terminals, make sure they're clean and tight. I also suspect that your battery charger is not working. To test : put your meter on the + and - output terminals from the charger. Plug the charger in and switch on, you should get at least 14.0 volts D.C on your meter.