Hi, my battery light keeps coming on and off randomly in my car. I had the battery and alternator checked they said the output was fine. We’ve tightened all the bolts. My alternator is less than a year old and I’m not sure about the battery. Does any one have some ideas on what the problem could be. (The other day while I was in the freeway my battery light came on then I lost power steering for a split second then the car went back to normal I’m just trying to get an idea of what it could be) if I can’t find answers I’m taking it to Toyota when I get back in town.

 

The battery light signifies low voltage or an issue with the charging system.

Since tests came back saying the alt is fine, the only other thing I can think of is that it sounds like a loose ground off the battery or a bad connection between the alternator and rest of the charging system. Check your battery connections and any engine grounds you have. Also if you've added any additional electronics to the vehicle (inverter or amplifier) double check that wiring and those connections to see if anything is grounding out.

 

we’ve checked the bolts on the alternator and battery, I’ll go throw and check everything again maybe there’s something I missed. Thank you for your help. I just know the alternator was put in, in like October so it’s been almost a year and I feel like I would have had the issues sooner if it was the connections on the alternator but they could have become loose with driving and bumps and snow and what not.

 

Did you ever figure out what was causing the battery light to come on. I have replaced my battery and alternator and tested them both and I'm having the same issue
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So ah… what transfers power from alternator to battery?

How would you know if 100% of alternator’s power actually makes it to battery?

Charge light on dash is in Y arrangement between alternator and battery. IF
alternator power at battery cable IS LESS THAN battery voltage, light turns ON.

Why would alternator power at battery cable be lower than battery itself???

This is literally 5-minute fix with multimeter…