moondance

The voltage reading on the dash seems to be a little screwy at times. The other day when sitting in a drive thru it dropped to almost red. The next day it was just under or over 13v. I went by Advance Auto and they did a load test and said the battery was bad and the alternator was good. I replaced the batter but it still reads right at 13v and sometimes on start up its under 13v with the air on. It eventually hits right at or just over 13v after running for a min. Could their load test on the charging system be incorrect and I have a bad alternator? It seems it should never be under 13v if its running. Thanks for the help.

rclearyiii

Use a volt meter and measure the voltage with the car running directly from the back of the alternator. Just be careful when doing so. This will actually verify that the gauge is correct inside the car.

moondance

What reading should I be looking at? And is there only two wires out the back of the alternator? That way I know exactly what Im looking for to plug into it so I dont mess nothing up lol.

bw_hunter

The fat red one under the rubber boot.....

n2ceptor

With the vehicle idling at normal temp, use a mutimeter and check the voltage at the battery.... Should read around 13.5~14.2........

rclearyiii

Check it at the battery and also check it at the back of the alternator to ensure the wire from the alternator to the battery is ok as well.

moondance

Car off it was 12.9 at the battery. Car running it was 14v at the alternator and 13.9 at the battery. Under a load it was 13.6 at the alternator and 13.5 at the battery. So guess its putting out what it should be. Can Alternators work sometimes correctly and not at others? or are they either good or bad not both sometimes?

n2ceptor

With the engine idling, turn on all assy(lights, A/C, radio), and check voltage at battery.... Should stay around 13+ volts....

moondance

I did that. That was the under a load reading. Straight running it was 14v at the alternator with the other stuff on it was 13.6. Thats why I asked if the could go bad and work properly sometimes but not others.

rclearyiii

Sounds like you are in good shape electrical wise. I would just drive and monitor the situation over time.

n2ceptor

OK.. Its seems normal...... How old is the alternator???? If it changes again, it might be a bad regulator.. Its internal, so just get a new alt....

moondance

not sure how old it is. It was on when I got the car in feb. I hate that things are already breaking. I was TDY for 4 months since I got it. I want to fix it up but didnt want to be forced already lol

moondance

I did notice when I put it in drive with all the other stuff turned on the voltage dropped midway between red and 13.