show 14V or more when you start the car but as the car warms up it will go down to 13V or less. This will happen no matter what accessories are on.

The alternator was changed and the new one did the same thing, so I got another one and tested it before I put it on and tested the one I took off. They both tested the same.

When I was changing it I checked the wire to the battery and it looked like new. I also checked the other plug and put some more of that dielectric (sp?) grease on it.

The belt was changed about 15, 000 miles ago and it looks fine.

What might be causing this? I think it's heat related but I don't know what else to try. There's not a lot there to try. I thought it might be the belt but it looked good. I figure I'll try the belt in a few days if it keeps doing this.

Thanks

 

Your alternator is working fine.
When you start your car you use up some power from the battery your alternator is replacing the used up power and when it does the needle will drop down and charge normally.
Bottom line, it is supposed to do this.

 

It didn't start doing this until two weeks ago and I've had the car for 4 1/2 years.

 

I wish mine did that.mine starts out at 13 then goes in the red if I am stoped and the fans come on. thats with a new alt. too and no UD pully

But yours is fine.

 

Mine has been doing the same thing for the last few months, when i first noticed it, I took the alternator in and got it tested. They said it works fine but it was putting out about 20 amps less then it should be. But I haven't had any problems with it other then the gauge showing that it is putting out a low voltage. Mabe the battery has somthing to do with it.

 

Your description is still within the range of normal operation, like revtime said. Maybe the difference is the age of your battery.

 

When an alternator warms up, it will not produce the same output as when it is cool. That is one reason the alternator puts out more juice when the car is cold. You might notice that if left to idle for a while, the alternator's output will drop significantly. But drive along and cool that puppy back down, and output comes back up.

 

The battery is a red top. So I don't think that's the problem and I had it tested also, it tested fine.

This maybe within acceptable range but with a new alternator that's not acceptable to me. (I've tried 2 new alternators)

If it's because of heat why didn't the old one do it? I sat in traffic for 6 hours in Panama City Beach and only moved 2.5 miles in that time and never once did the gauge read low. That was last year. This one does it as soon as the temperature gauge starts to come up; I'm talking about 150 degrees not 190+ degrees.

 

your alt is fine. I dont even know why it stayed at a constant 14v before anyway. Mine does that same thing its 14 at startup and will go to 13v sooner or later. your 12 volt battery is still getting charged from the 13 volts the alt is puttin to it. but feel free to replace as many alts as you wish.

 

I just thought I would come back and post this for anyone who might do a search in the future.

Well after not worrying about iot for a few a while. The battery went out on me the other day. I think I have driven it twice since early August. I went to start it to let it run for a while and it wouldn't turn over. I jumped it off and let it charge. Well the next day I was going to drive and the battery was dead again. I took it to get the battery tested and it was bad (the battery was a Red Top). Well anyway I got a new and and now the volts read were they did before. So I think that was my problem.