Alternator high voltage? (15.3V)
Senior Member
Joined: Dec 2011
Posts: 443
Likes: 0
From: Durham, NC
Some observations:
April 6th:
Charged battery, Voltage was 12.9V (battery disconnected)
1 hour later 12.6V
20 hours later:
Voltage was 12.45
Overnight temperature just below freezing (-2,-3 degrees C)
Well, maybe the battery is still fairly OK, guess a load test will determine that. I will have to talk to the guys at KalTire or NAPA and see what method they use. I cannot really leave the battery there overnight as I have no replacement now.
Purchased the battery at KalTire about 2 years ago.
DieHard Gold
No 658MF
Series 2000
Rating (CCA) 58-580
Rating (CA) 725
I am still a bit uneasy about the alternator voltage, but will now keep a close look on it as the weather warms up.
My thanks to all of you who provided good feedback to my questions.
Take care and have a Happy Easter with family, friends and good food!
April 6th:
Charged battery, Voltage was 12.9V (battery disconnected)
1 hour later 12.6V
20 hours later:
Voltage was 12.45
Overnight temperature just below freezing (-2,-3 degrees C)
Well, maybe the battery is still fairly OK, guess a load test will determine that. I will have to talk to the guys at KalTire or NAPA and see what method they use. I cannot really leave the battery there overnight as I have no replacement now.
Purchased the battery at KalTire about 2 years ago.
DieHard Gold
No 658MF
Series 2000
Rating (CCA) 58-580
Rating (CA) 725
I am still a bit uneasy about the alternator voltage, but will now keep a close look on it as the weather warms up.
My thanks to all of you who provided good feedback to my questions.
Take care and have a Happy Easter with family, friends and good food!
Senior Member
Joined: Apr 2001
Posts: 1,549
Likes: 0
From: This side of the Milky Way
A failing battery will however. Just this past summer (113 degrees record temperatures in Dallas) the stock Ford battery started going out (great battery btw, lasted almost 6 years) and I was consistently getting 15s to even low 16 volts at highway speeds. Since I didn't want to be stranded I decided to shell out some serious dough for an upgrade (DieHard Platinum/restamped Odyssey battery) Problem solved, voltage stays very consistent nowadays, at any speed.
Last edited by LeanNCut; Apr 14, 2012 at 02:49 PM.
Technical Article Contributor
Joined: Jun 2002
Posts: 10,511
Likes: 10
From: Under the flightpath of old ORD 22R
A failing battery will however. Just this past summer (113 degrees record temperatures in Dallas) the stock Ford battery started going out (great battery btw, lasted almost 6 years) and I was consistently getting 15s to even low 16 volts at highway speeds. Since I didn't want to be stranded I decided to shell out some serious dough for an upgrade (DieHard Platinum/restamped Odyssey battery) Problem solved, voltage stays very consistent nowadays, at any speed.
Senior Member
Joined: Jun 2011
Posts: 447
Likes: 3
From: Houston,Tx
buy the battery keep reciecpt put in truck connect it,,, start it up. check the voltage going to the battery. If it's not at least 14 you have an alt problem,, if its 14 or more the battery can be kept. if its not at least 14 take battery back then look at alt replacement.
I love all the tech info put out. And i am not saying anything about the people that put it out.
But i believe K I S S is a good idea when troubleshooting. 
K I S S = keep it simple stupid
I love all the tech info put out. And i am not saying anything about the people that put it out.
But i believe K I S S is a good idea when troubleshooting. K I S S = keep it simple stupid