JSMax

iTrader: (13)

How can I tell if my alternator is going bad?

I got into it today with a local mechanic. He thinks my alternator is the culprit, but I don't believe him.

Here's the story... Autometer volt meter is hooked up to the cigarette lighter. For about the last 2-3 months, it has been reading ~14 volts upon startup. As I drive the car, the voltage drops. I usually spend about 20 minutes in the car on the way to work. The volt meter drops to around 13 volts on the way to work. After the car sits for 8 hours, the voltage reads 12+ just before start up and 14+ at start up. On the way home, voltage drops to around 13.
So, today he (mechanic) hooked up a voltmeter to the battery and it read like 12.83 volts. The car was running. I HAVE An Under Drive Crank Pulley on the car.

The battery has been discharged fully just within the past few months. I left the car alarm on (armed) for a week. Went on holidays and came back... no juice. This battery has been discharged a few times. After that last time, I hooked up a trickle charger and let it go overnight.

Again, the mechanic thinks it's the alternator, but my guess is on the battery. With a combination on the udp not fully charging the battery every use.

What does the .org think? I'd rather not have to replace the alternator ($$$) but if that's the case, it will be done.
thanks

Digital

iTrader: (1)

UDP gonna take a minute for the engine to get use to it, and the alternator as well. I'd check the battery, or get a new one. First.

I have a UDP and the first few days my car would stall at lights or stall going from say 2nd to neutral. Now it's fine.

JSMax

iTrader: (13)

Yeah, I've had the udp on for maybe 4 years now. should have put that in the first post.

MrDicks95SE

iTrader: (23)

try hooking up the battery in another car if possible and see if it really is the battery or replace the battery with a new one.

MaximaSpd85

iTrader: (14)

go to your local autozone or advance auto and they will check your battery and your alternator for free. of course if there is one around you...

JSMax

iTrader: (13)

that's a good idea... do I have to remove the alternator for them to test it?
I can have the battery tested tomorrow... hopefully that's the culprit.

MaximaSpd85

iTrader: (14)

no, you do not have to take the alternator off.