If lights dim when jumper cables are disconnected, you have a generator problem. You can prove that by measuring the battery voltage. With the engine off, it should be 12.6 volts. If it's around 12.2 volts the battery is good but discharged. It should be charged at a slow rate for an hour.
With the engine running, the battery voltage must be between 13.75 and 14.75 volts. If it is low, the charging system is not working.
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Tuesday, September 15th, 2015 AT 5:36 PM