battrey light

Ensure the battery cables/connections at the battery are tight. By chance was the battery disconnected with the engine running as this makes the voltage stabalizer in the alternator make the alternator charge at peak capacity and may damage the alternator. Check for power at the back of the alternator, the heavy wire brings power back to the battery, the ignition switch brings power to the energizing wire at the alternator so one wire at the alternator should be live with the ignition key n only. With the engine running have a friend watch the "battery light" on the dash as you strike the alternator with a hammer (not a huge blow), if the light goes out you have an internal fault in the alternator. If you have a voltmeter, put it across the battery at rest a fully charged battery should read 12.6 volts. Start the engine the voltage across the battery should read approximately 14.7 volts if the alternator is charging.