Battery Indicator Light

[dadenkern]

- 2001
- Non Sport
- 108,000 miles

What exactly is the batttery indicator light indicating (technically)? The owners manual simply says to see a qualified repair shop for a complete charging system inspection.

Is the light measuring the voltage difference between the output of the alternator and the voltage across the battery? or?

I've tried the 4 gauge jumper wire solution from the output of the alternator to the positive side of the battery and my battery indicator light remained on.

[investor74]

The indicator light is supposed to tell you that there is a net outflow of current from the battery when the engine is running. If the alternator is charging properly and the battery is capable of being charged, there should always be a net inflow, or no net current flow when the engine is running.

I've had my 97 for a long time and have never got useful information from the battery light. It never came on to warn me when I had alternator or battery trouble. Looking back on it, however, the built in voltmeter was indicating trouble if I knew the warning signs.

What is your voltmeter saying? Now that I have a good battery in there, mine shows close to 14 volts on the highway. Before maybe 13 volts.

Barry

[dadenkern]

Yesterday (2-5) the voltage indicator suddenly dropped to just above the red zone during my drive to work. After shutting off the heated seats and heater the voltage returned to a near normal reading. When I went to start my car after work the car was completely dead, after a jump start the car ran fine all the way home (48 miles). A voltage reading from the battery when I got home showed ~12V. I then put a charger on the battery for a couple hours and the car started fine and showed around 13V. The battery indicator light came on after the battery was charged.

I also took it to the local NAPA and their equipment showed that the alternator is bad. The battery is about 6 months old.

[dadenkern]

Follow up:

Replaced the alternator last night with a GM-Bosch unit and all is well. The battery indicator light is no longer lit and the voltage gauge is around the 14V mark.

[Marks DTM Calib]

The battery light tells you if the alternator is outputting current......if its on then its not!

There are four basic faults

Noisey alternator - light off - Knackered bearings (can be changed with a puller)

Light On, Alternator not charging (low voltage at battery) - normaly a failed regulator (open circuit) or very worn brushes (rare)

Light off, high charge voltage, normaly a failed regulator (short circuit), this will cook the battery!

Flickering light - Failing rectifier pack......unknown on these units.

[dadenkern]

When I say the "battery indicator light on" I mean the color of the light is red. Normally the battery symbol is lit up and white. There must be another bulb adjacent to the battery symbol that is red and only comes on when problems arrise.

Now that the alternator has been replaced the battery symbol is white again.

[AwfulSmokey]

Battery symbol is normally lit up? I dont think so. Sounds like that's your problem right there. You are referring to the light in the dash, correct?

[dadenkern]

Well, my charging system has failed again. Suddenly on my drive to work yesterday the voltage dropped into the red zone and I barely limped the car to work. I've pulled the alternator out again and am going to get it swapped this afternoon.

What system or condition could cause an alternator to fail after 10 days in use? Or was could it be a poorly manufacturered unit? Before taking the alternator out I connected a secondary wire from the alternator to the battery and the voltage still did not return. The field coil wire (blu/wht) had ~6V during idle and great continuity between the alternator and the brown connecter behind the battery.

I've read numerous posts concerning adding a secondary charge wire from the alternator to the battery. Since the starter uses the primary lead from the battery this would suggest that the secondary lead from the starter to the alternator is faulty?

[investor74]

I think there is a lot of junk out there being sold as "rebuilt" alternators.
A while ago, I was playing "muscial alternators", lasting from 2 months to about a year. Of course, they were all from the same independent shop who claimed they were giving me "rebuilt", not used alternators. I was told I had a parasitic leak, etc.

I tried to get a new, not rebuilt alternator, but was told that there is no such part. I was willing to pay anything for a good alternator.

My problems all stopped when I got an alternator put in from a different source.

Barry

[dadenkern]

Update:

I exchanged my suspected failed alternator and installed the new one Friday night (2-16). I also installed a separate 6 gauge battery cable connecting the alternator to the battery directly bipassing the starter. So far all is well, the battery indicator light is no longer red and the voltage is around 14 - 14.5 while cruising.