I have a 2006 Hyundai Tiburon. Have had battery die before when leaving lights on etc. however recently I pulled into a station to get gas, turned off the engine but left the radio on. About 2 minutes later the radio and clocks shut off and there was no power. When I tried to restart the first two times it made that clicking noise like it was a dead battery…then on the 3rd attempt it started. How can I tell if this is a battery or alternator problem?
It is possible that a 2006 car may need a new battery, but it is a little early. I doubt if it is the charging system, but it is possible.
The first thing that I would check are the cables. Check each end of every battery cable. Disconnect it, clean both contacts and reattach it.
If you have the car running, stop by most any auto parts store and most will check the battery and charging system for free.
Have the battery and the charging system tested. Many auto parts stores will do this free. The battery should be “load tested.”
Maintenance free battery do not tolerate being run completely dead, so it is safe to say that the life has been shortened and the capacity was reduced by being drained.
The radio and clock going black, followed by the car successfully starting, is highly unusual, and points to an intermittent electrical connection somewhere. Check/clean your battery connections, particularly the end of the ground cable that attaches to the frame.
If you find no problem, buy an inexpensive voltmeter and measure the voltage across you battery terminals when the car is running and when it is shut off. You should have 13.5-15 volts when running at fast idle (lower voltage suggests alternator problem), 12.6 volts when shut off, and no less than 9.5 volts when cranking the engine (lower means discharged or failing battery).
The battery contacts are likely the problem. BUT if the battery or alternator is dying, cleaning the contacts may make the battery/alternator problem go away … for about 72 hours. This is, needless to say, really annoying if one is not prepared for the problem coming back when the battery gets a little weaker.