Idle voltage

[scorched]

So, I am curious to if my alt is on its way out. I just got a new ford battery in april. Sucker is no longer holding a charge. So I jumped the car, and decided to test alt voltage.

At startup, it puts out 14.1 volts. Then when the car gets up to temp, it went down to around 13.7 and stayed there at idle. Is this an indication that the alt is bad? And may have killed my new batt?

 

[scorched]

Ttt. Anyone?

 

[scorched]

No one?

 

[sonic cobra]

Mine was fine at high 13's for years. I think you can check output at idle with accessories off. Then turn everything on and if output drops you have an alternator problem

 

[Mystic03]

mine was fine at high 13's for years. I think you can check output at idle with accessories off. Then turn everything on and if output drops you have an alternator problem

+1

 

[scorched]

Seems to dip to about 13.1-13.2 with ac, radio and rear defrost on.

 

[SVTDice]

If it starts dipping into the 12's I'd start getting worried. Mine is 12.2-12.6 and its shot.

 

[BMR Tech]

I agree, if it dips into the 12's....that is usually a solid indicator.

I have a simple method. I go make a 3rd/4th gear pull and log voltage. You will be able to tell if it is up to par by doing so.

 

[sonic cobra]

Mine is shot also. A ford reman with 30k on it. 170a billit tech on order

 

[MrCaliKrome]

I agree, if it dips into the 12's....that is usually a solid indicator.

I have a simple method. I go make a 3rd/4th gear pull and log voltage. You will be able to tell if it is up to par by doing so.

I have a similar situation as the OP.

I logged a short pull in 2nd and 3rd and my volts dropped into the 12s.

In 3rd @ 4100 rpm voltage dipped to 12.63. The red boxes highlighting the dip while accelerating in 2nd and 3rd.

Does the log below warrant a new alternator?