Quote:
Originally Posted by Agouti
You will only get voltage drop and under-reading if significant current is drawn down those same wires OR there was a wiring issue causing high resistance (volts equals current times resistance). A 1V drop between battery and accessories plug without load would be of concern.
Both multimeter and plug voltmeters are cheap so it is easy to check. Just make sure to get ones which state the accuracy.
You should be sitting at between 13. 8 and 14.2V when the car is running. Too high means the alternator regulator is bad and you will boil dry your battery (plus possible electrics issues), too low and the battery will not charge properly. It may be a little low at idle and/or immediately after starting, ideally test across a range of rpm.
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Yes exactly, if his readings are like that then his alternator is perfectly fine, it charges fine. It has to charge 14 volts when the car is idling.
All he has to do is disconnect the little sensor on the battery, wait a few seconds then plug it back in while the car is off, and the message will disappear.