My 2007 Elantra will not start. Turn the key and nothing. New battery, alternator good. Cleaned battery cables and the ground to the car. Put the battery charger on for a few seconds and it starts and will run for the rest of the day. Help!

 

Get a DVOM or multi-meter and check voltage across the battery terminals
Both when the engine is running and not running
Running should read 14 to 14.5 volts
Not running should read 12 to 12.5 volts
Remember that new doesn't always mean better/working right