i was wondering if its time i replace my alternator. latley under the hood its started to make a humming/howling noise. and increases with rpms. ive noticed on my voltage meter on my radar detector that on idle with my lights off i read 13.8- 14.1 volts. when i turn on my headlights it drops to 12.4-12.8 and with the heater on it drops as low as 11.8-12.2 then with window defroster and wipers the low voltage warning on the radar dectector comes on. no battery light on dash tho. is this normal. it dosnt seem as tho it is. i dont recall my voltage dropping this low with accesories on. when i drive or raise rpms the voltage goes back to 14 range. sometimes after all the accesories being on after a short trip it takes a bit to start the car again like the battery is drained. any sugestions. i think its the alternator. perhaps should i upgrade to a high output while im at it?
alternator probably has a bad diode, alternator should read at least 13.4 volts when idling with all accessories on. Had the same problem even after checked OK at autozone, their check shows whether there is some output, not whether it works right under heavy loads. Time to swap in a new one.
Your alternator is aging, but not dead yet. I didn't know radar detectors had voltmeters, but if it works, your headlights off numbers are correct, as with all accessories on, you should only be concerned if it drops below 12, that means it's almost dead. They are expensive but it's your money.
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Bad Alternator?
Linear Mode
