Battery Light on Startup

[grfsSHO]

After replacing the original (!!) battery in my '98 SHO this past summer (approx 160,000 km. / 100,000 miles), I now have an intermittent condition where the 'battery light' comes on for 10-15 seconds right after start-up, then goes out. Battery was bought at Canadian Tire and I believe is an Exide. Alternator load tests fine (~130 Amps). And, with voltmeter, reads 14.2V and higher at start-up, settles around 13.8-14.0V at idle.

Battery tests with engine off @ 12.5 -12.6V, plus parasitic drain normal at 20mA.

Any ideas for what's causing this? It seems to indicate to me a battery problem with the alternator having to charge for a bit after starting...plus the cold spells here in Alberta seems to make it occur more often.

Cheers!

 

[Mr Anonymous]

Are you testing the alt during that 10-15 seconds that the batty light is on? I bet you would see different results. You'll want to start shopping for a new alternator soon.

 

[grfsSHO]

Yes, have tested it multiple times with the light on..always at 14.2V or higher...

Is it possible, (and to confirm my thinking), that the light comes on at times when the alternator is below optimal charging levels, as well when the battery is in need of a charge? Looking at the circuit diagram for the 'battery light' and electrical/charging system, looks like they both have to be in balance for the light to go out.

 

[naval-avi8or]

Battery light doesn't mean your battery is bad it means your charging system isn't working properly and your battery is running the most or all of the electrical load.

 

[Mr Anonymous]

Yes, have tested it multiple times with the light on..always at 14.2V or higher...

Is it possible, (and to confirm my thinking), that the light comes on at times when the alternator is below optimal charging levels, as well when the battery is in need of a charge? Looking at the circuit diagram for the 'battery light' and electrical/charging system, looks like they both have to be in balance for the light to go out.

No. As Curtis said, the battery light actually has nothing to do with the battery but instead it's a switch in the voltage regulator that illuminates the light at set high/low threshold voltages of alternator output only.

The only time you should see a batty light on a good alternator is if the alt is under about 300 RPMs, which is only for the first 2 seconds of cranking.

 

[SHOZ123]

Could be the connector on the alternator.

 

[grfsSHO]

Thanks, gentlemen!
I'm beginning to think that it's a connection problem, as Paul as suggested. Had the charging system and battery tested again, all normal. Will be checking all connections tomorrow.