How many volts should an alternator put out at idle?
Category:
automotive
auto parts
A car alternator needs to be putting out at least 13-14 volts (ideally between 13.8 and 14.2 volts) to effectively charge a 12 volt car battery. If the alternator is putting out too much voltage (15+ volts), it is likely your battery acid will boil over out of the battery.
Herein, what should voltage be at idle?
14.3 volts
Considering this, what should an alternator charge at idle?
At idle, most charging systems will produce 13.8 to 14.3 volts with no lights or accessories on (although some may charge at a slightly higher voltage depending on temperature, engine RPM, type of battery, and the battery's state of charge).
Yes, the alternator does charge the battery while the car is idling - regardless of the load on the battery. However, if your electrical use load (radio, lights, fan, etc) exceeds the amount of charge the battery is receiving from the alternator, you will end up with a discharged battery at some point.