Glowing Battery Light

[DoctorPDR]

I wanted to find out if the battery light glowing on my tachometer is normal. I usually notice this when my headlights, heater fan, and wipers are on. It will even glow a little without the wipers on.

[Snoopy]

I have seen this at several Spiders. I think a combination of old parts...

[Foster48x]

Are you talking about the battery light? Not sure if your having the same issue but I had a similar problem with the battery light coming on when the ignition was off. Ended up being a toasted alternator. May not be the same issue but here's a topic on mine.

http://www.fiatspider.com/f08/viewtopic.php?f=6&t=6767

Rick

[DoctorPDR]

Are you talking about the battery light? Not sure if your having the same issue but I had a similar problem with the battery light coming on when the ignition was off. Ended up being a toasted alternator. May not be the same issue but here's a topic on mine.

http://www.fiatspider.com/f08/viewtopic.php?f=6&t=6767

Rick

Hey Rick,

The battery light on inside the tachometer. It glows when I have the headlights, heater, and wipers on. It will also glow a little when I just have the headlights and heater on, or headlights and wiper on. When I only have the headlights on, it will NOT glow. When I say glow, I'm referring to a very faint illumination. It's not bright at all.

[SLOSpider]

If its glowing at idle then your idle may be set a bit low or you can always increase it by 100 rpm or so.

[DoctorPDR]

If its glowing at idle then your idle may be set a bit low or you can always increase it by 100 rpm or so.

With further testing, it seems to get brighter as the RPM's rise. I noticed this since day one. If I'm cruising and the RPM's are around 5000, the light gets real bright. Don't think this has anything to do with the idle, but thanks for the input.

[SLOSpider]

I would start with checking the voltage at the battery and see what readings you get at idle and again at 2500-3000 rpms. Post up your results.

[danaspider]

The glowing alternator/battery light is not normal. The circuitry is designed to have the light come on when Alt voltage is lower than the battery voltage. Has anything been rewired recently, prior to it starting to happen? Look at static battery voltage and then look to see what the output from the alternator is. battery is a little over 12V, running car alternator 14.8 volt.

Have you checked all of your ground point connections? Cleaning these and comparing the voltages will give us a clue.

[baltobernie]

You're seeing a dim Alternator light at low RPMs because the voltage at the alternator is lower than the fuse panel voltage + Alternator light resistance. When the RPMs increase (or other loads decrease), the voltages at the two ends of the circuit are about equal. Thus no current flows thru the lamp. See my Reply on "Death of an Alternator" post in this section.