When running the Voltage Regulator in the Alternator should make sure that no matter how high you rev it does not go above (On most cars) 14.5 Volts. if you are getting over 12 Volts after it sits all night the battery is OK. It may be the Alternator Drive Belt is slipping a bit.
Andy C
check the voltage while it,s running, it should read 14 volts ! most batteries will lose a volt or 2 sitting but nothing to worry about as long as your alternator is good !
13.5 volts while running is OK. If it cranks over and starts with out a problem in the morning you don't have a problem.
You need to load test the charging system to see how many amps. your alt. is putting out. Not knowing what you have the amperage should be 40 to 50 amps. You need to load test the battery also. Take it to a shop.
It always read more when it is running. The battery is fine.
What's up guys, I just replaced my alternator and battery 2 days ago. When I put the battery in for the very first time, I checked the voltage before I turned it on and it read 12.2. When the car is on it reads 13.5. When I checked it in the morning after letting it sit overnight it read 12.1 - 12.2. Am I fine? Voltage seems pretty low!!
