battery-alternator problems - Ford Powerstroke Diesel Forum
Powerstroke.org is the premier Diesel Truck Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-08-2012, 09:06 PM
Member
 

Join Date: Jan 2011
Posts: 61
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
battery-alternator problems

I was having a charging system problem yesterday. I stopped by autozone and had them test it. He told me the alternator was only putting out 12.9 volts. I took the alt off and took it in to have it bench tested and it passed at 14.7 volts. With the engine running I am getting 12.6v from the alt. I am getting 10.8v to the green exciter wire on the alt which seemed wrong. I then checked my batteries. Both were at 12.4v disconnected. I connected one and got 12.2v. Then I disconnected that battery and connected the other one and got 10.8v. I switched the batteries and the one battery always drops about 1.5v when connected no matter what side it is connected to. This may be a dumb question, but is it possible for a bad battery to lose 1.5v when connected? The low voltage battery was originally on the passenger side. Will 10.8v to the exciter wire cause a low output on the alt? I checked all grounds and cleaned all the terminals. Thanks in advance
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 11-08-2012, 09:39 PM
Serving Our Country!
 

Join Date: Aug 2007
Location: Manor, TX
Posts: 2,890
Thanks: 0
Thanked 18 Times in 17 Posts
Feedback Score: 2 reviews
Looks like you have a bad battery. With the batteries disconnected you are seeing a surface charge of 12.4v, with them connected there is a light load and the true battery voltage is showing. Try charging it overnight, if you still have 10.8v then replace both batteries.
Reply With Quote Quick reply to this message
  #3  
Old 11-08-2012, 10:09 PM
Member
 

Join Date: Jan 2011
Posts: 61
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
that is correct but only one battery does this. Will low voltage to the exciter cause low output from the alt?
Reply With Quote Quick reply to this message
  #4  
Old 11-09-2012, 08:24 AM
Compression Ignition Addict
 

Join Date: Jul 2007
Location: Spokane Washington
Posts: 497
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 1 reviews
Quote:
Originally Posted by schemi View Post
that is correct but only one battery does this. Will low voltage to the exciter cause low output from the alt?
When you t n your ignition to the on position and your dash lights come in, does your battery indicator come on, or is it dimmer than the other. I had a similar issue and it was that indicator bulb being dimmer that caused my issue

Sent from my PG86100 using AutoGuide.Com Free App
Reply With Quote Quick reply to this message
  #5  
Old 11-09-2012, 06:47 PM
Serving Our Country!
 

Join Date: Aug 2007
Location: Manor, TX
Posts: 2,890
Thanks: 0
Thanked 18 Times in 17 Posts
Feedback Score: 2 reviews
The alternator is either on or off. Try this, disconnect the - on one battery, start the truck and see where the voltage is. I am guessing one battery is pulling the alternator down to 12.9v which will eventually kill the alternator. You should replace both batteries at the same time.
Reply With Quote Quick reply to this message
  #6  
Old 11-09-2012, 07:55 PM
Member
 

Join Date: Jan 2011
Posts: 61
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
There was no dash lights. I took the batteries in and the one battery tested bad. Replaced both.
Reply With Quote Quick reply to this message
  #7  
Old 11-29-2012, 08:28 PM
Powerstroke.org Rookie
 

Join Date: Nov 2012
Posts: 16
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
schemi......did replacing both batteries fix your problem ?
Reply With Quote Quick reply to this message
  #8  
Old 11-29-2012, 10:47 PM
Member
 

Join Date: Jan 2011
Posts: 61
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Yes it did. There was one bad battery. I replaced both but kept the good one for the jeep.
Reply With Quote Quick reply to this message
  #9  
Old 11-30-2012, 08:16 AM
Powerstroke.org Rookie
 

Join Date: Nov 2012
Posts: 16
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Thanks for the response, having a little trouble here, new alternator, one new battery, not charging at all.
The old alt. started over charging and seemingly draining batteries when not running so I replaced it. One battery was bad so I replaced that as well.
I sent the alt. back, the guy tested it and says it's fine.......not quite sure what the problem is yet.
Reply With Quote Quick reply to this message
  #10  
Old 11-30-2012, 07:06 PM
Member
 

Join Date: Jan 2011
Posts: 61
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Get your other battery tested. It could be bad dragging everything else. that is what my problem was
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Ford Powerstroke Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -8. The time now is 12:52 PM.


Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.1
Garage Plus, Vendor Tools vBulletin Plugins by Drive Thru Online, Inc.

vB.Sponsors