 Battery charging without ALT light, What’s going on? |
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| VaccaRabite |
 Sep 30 2026, 02:06 PM
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#1
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En Garde!  Group: Admin Posts: 13,921 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region 
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A friend of mine had his battery pop in his 914. Battery acid everywhere. We got it running last weekend after a year of sitting.
Of note, the alternator light never turns on. BUT, the car is charging the battery at 13.9 volts. How is this possible? My guess is that he has a damaged or failing diode in the alternator, but I thought the battery COULD not charge without the alternator light turning on. So I’m confused. Thanks Zach |
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| SirAndy |
Sep 30 2026, 04:45 PM
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Resident German Group: Admin Posts: 42,530 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
Wait, i'm confused. The alternator light is supposed to be off when the car is running.
Are you saying it doesn't come on with the key on but the engine off? Does he even have a bulb in there? Did anyone bypass the light? I have seen so much hacked wiring in 914s. (IMG:style_emoticons/default/idea.gif) |
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| VaccaRabite |
Sep 30 2026, 05:05 PM
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#3
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En Garde! Group: Admin Posts: 13,921 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region
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QUOTE(SirAndy @ Sep 30 2026, 06:45 PM)  Wait, i'm confused. The alternator light is supposed to be off when the car is running. Are you saying it doesn't come on with the key on but the engine off? Does he even have a bulb in there? Did anyone bypass the light? I have seen so much hacked wiring in 914s. (IMG:style_emoticons/default/idea.gif) Correct. The light never turn on. He replaced the light with another bulb today and it remains off. None of the bulbs on this car are LED. The light used to come on normally as far as I know. I’ve driven the car and that’s something I would have noticed. But the alt is getting field from somewhere I guess. Just not the right place. Zach |
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| porschetub |
Sep 30 2026, 11:34 PM
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#4
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914 Guru Group: Members Posts: 5,179 Joined: 25-July 15 From: New Zealand Member No.: 18,995 Region Association: None |
QUOTE(VaccaRabite @ Oct 1 2026, 12:05 PM) QUOTE(SirAndy @ Sep 30 2026, 06:45 PM) Wait, i'm confused. The alternator light is supposed to be off when the car is running. Are you saying it doesn't come on with the key on but the engine off? Does he even have a bulb in there? Did anyone bypass the light? I have seen so much hacked wiring in 914s. (IMG:style_emoticons/default/idea.gif) Correct. The light never turn on. He replaced the light with another bulb today and it remains off. None of the bulbs on this car are LED. The light used to come on normally as far as I know. I’ve driven the car and that’s something I would have noticed. But the alt is getting field from somewhere I guess. Just not the right place. Zach Wow that is weird ,without the lamp working there is no excitation for the alternator , the load the lamp has is enough to trigger that due to current used ,as you mentioned it could be sourcing load from elsewhere ? strange one hopefully Spoke will pop in ? |
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Posts in this topic
VaccaRabite Battery charging without ALT light Sep 30 2026, 02:06 PM
Artfrombama If you have an old battery that never fully charge... Sep 30 2026, 03:38 PM VaccaRabite Battery didn’t explode persey. But it did spray ... Sep 30 2026, 04:41 PM
930cabman Please clarify, how/why would a battery pop or spr... Sep 30 2026, 04:51 PM
VaccaRabite Not my car and I’m currently 100ish miles from i... Sep 30 2026, 05:02 PM |
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