Have the battery tested or measure the voltage during cranking. Put the meter probes right on the battery posts. You must have 9.6 volts or higher during cranking. If it is less, the battery has a shorted cell or it has not been getting recharged while driving.
If the voltage is above 9.6 volts, move the probes to the cable clamps and measure again. If it is lower there, one of them has a bad connection.
Thursday, May 2nd, 2013 AT 9:05 PM