Testing alternator

[v8stang67]

Using a multimeter, how can I test my alternator and battery to see if they are working right? I had to jump the car to get it started and after about a 5 mile drive, the battery was still dead as a door nail. The battery is not that old, but it does see pretty infrequent use. I'm going to put the trickle charger on it this afternoon and see what happens. I know I can take them down to autozone to get checked for free, but the car isn't registered and inspected and I don't want to chance it.

 

[ron67fb]

Battery voltage should be about 12.6v with the engine off. With the engine on, the voltage at the battery should be around 14v for proper charging. Check at the terminals, then at the posts. It might be charging okay but the posts may not be connecting too well to the terminals.

Without an amp meter you can' t really check the system under load. You could at least bring the battery to them and have it load tested.

edit - btw 5 miles might not be enough to charge a completely dead battery.