Battery Light My battery light keeps coming on. I took my car to a shop and the mechanic said the alternator was fine and it's telling him to replace the battery. So I replaced the battery and the light is still coming on. Was this mechanic just a bad mechanic and does not know what he is doing, and the problem is the alternator?

The voltage regulator is built into the alternator. If the wires in the alternator connector are good, the problem is in the alternator. Take it back to the shop.

Start with the first mechanic who replaced the battery and have them check the charging system. (Alternator) They should have done this when changing a battery, to rule that out as a problem in the first place. Explain the problems you have been having, as a bad charging system can cause all sorts of electronics problems and have them check the engine codes and have them explain what they are.
You could also go back to the muffler shop and tell them their sensor replacement did not fix the problem and have them correct their work.
Diagnosing Alternator Problems EricTheCarGuy

People have this notion, especially older mechanics and 1/2 Witt mechanics that disconnecting the cable will tell you if the alt is good or not. On older cars disconnecting the battery while running was ok on newer cars you NEVER do this. People time and time again think this is ok, it\'s not, you will severely f&$@k up the regulator and possibly the ECM causing a new problem that was not there before. The alternator could be putting out voltage fine but the problem usually lies in the amperage. It\'s fine to have a few things on but once load is applied everything will fall apart.

diodes in alternator are leaking (back feed), more when hot. needs alternator or fan belt loose..

The BATTERY Light coming on is telling the charging system is not charging the battery . Take it to a qualified repair shop . The abs traction lights coming on are due to low voltage .The charging system in your vehicle is computer controlled ,don't know what kind of mechanic you took it to ? Take it to a Chevy dealer

You are describing a situation that would be solved by a replacement alternator. You say yours is fine ... I think I'd be inclined to have it checked by another mechanic.

The battery light comes on when you are using more power than you are making. Your car died because it had no electricity to run the spark plugs, the electric fuel pump, the computer, the lights, the instruments, the cooling fans, the security system, the automatic locks, the heater/AC - ventilation system, and other electrical powered devices required to make a modern car run.

In the good old days, a battery would run a car for weeks, in the day time (no lights) - with the only power requirement was the starter and the ignition. Today - cars are power hungry.

Yes, your car ran out of power last night and this morning it strarted fine and ran for a while. That was because your battery has SOME capability to recover overnight. Don't push your luck. Have an evaluation done by a professional mechanic.

Thanks for your interest in FixYa.com

THE RED LIGHT SHOWS WHEN ITS NOT CHARGING I WOULD GET THE VOLTAGE CHECKED SHOULD BE PUSHING 13 TO 13.5 VOLTS WHEN CAHRGING

it could be just a bad contact at connector,and yes i would ask them to fix it,its atrouble indicator light of the charg. system

CHECK ALL WIRES THAT GO TO ALTERNATOR.CHECK BATTERY BY TESTER( LOAD).CHECK WIRES FROM IGNITION SWITCH (YELOW) WITCH GO TO ALTERNATOR.AND CHECK GREEN RED WIRE WHITCH GO TO ALTERNATOR WITH IGNITION ON. IT SHOUD BE 12V AND WITH ENGINE RUNNING IT SHOUD SHOWS NOTHING.IF EVERY THINK OK - REPLACED ALTERNATOR.WITH EVERY THING OK VOLTAGE SUPOUS TO BE 13.8 - 14.5 V

The alternator is what makes the battery light come on, it is telling you the alternator is not charging the battery