Alternator not Charging Under Load? - Ford Powerstroke Diesel Forum
User Tag List

 
LinkBack Thread Tools Display Modes
post #1 of 9 Old 03-25-2013, 08:33 PM Thread Starter
Compression Ignition Addict
 
jmsmith76's Avatar
 
Join Date: Sep 2009
Location: Middle GA
Posts: 1,480
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 4
Thanked 9 Times in 7 Posts
Feedback Score: 0 reviews
Alternator not Charging Under Load?

Hey fellas, got a charging question. Swapped out my alternator a few months back under warranty. Tested as having an open diode. It would charge fine most of the time but under load (headlights on), it wouldn't charge at all and the voltage would drop. Now it's doing the exact same thing again.

Just running during the day it does fine, but as soon as I cut on the headlights, the voltage drops. I'm wondering if my replacement alternator could be bad or if there is something else that could cause it. I'd hate to swap the thing out again and it not be the actual problem. Any suggestions on things other than the alternator itself that could cause it to behave like this? I've checked my wiring and it looks good after a quick lookover. The main plug does have a little corosion in it, but I don't know if that would cause it.
jmsmith76 is offline  
Sponsored Links
Advertisement
 
post #2 of 9 Old 03-25-2013, 09:14 PM
Compression Ignition Addict
 
svranger25's Avatar
 
Join Date: Mar 2010
Posts: 294
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
is it only when you use headlights or do other big loads do this too? could be a short in the headlight harness

-Brandon-
1996 F 350 7.3L CCLB
6637 Intake; Banks: Intercooler, Up Pipes, Turbo; PHP Phoenix
4" down-pipe, cat delete,muffler delete, 4" turbo back exhaust
Sky Jacker Suspension, Limo Tint, Cobra Classic 29 LTD,
Stage 2 TC, improved internals
Loudest, Proudest member of the Fightin' Texas Aggie Class of 2015!
svranger25 is offline  
post #3 of 9 Old 03-25-2013, 09:18 PM Thread Starter
Compression Ignition Addict
 
jmsmith76's Avatar
 
Join Date: Sep 2009
Location: Middle GA
Posts: 1,480
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 4
Thanked 9 Times in 7 Posts
Feedback Score: 0 reviews
Didn't think of that. I don't have anything else that really puts a load on it so haven't tested it any other way.
jmsmith76 is offline  
post #4 of 9 Old 03-25-2013, 09:35 PM
DERAIL MOD!!!


 
351fifty's Avatar
 
Join Date: May 2011
Location: Canton and kennesaw
Posts: 23,174
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 34
Thanked 205 Times in 193 Posts
Feedback Score: 4 reviews
Know anyone with a trailer you can hook up and hit the brakes?

-Kris-
2011 f150 ecoboost 4x4 323/452 on php dyno 11/16/13
1995 CCLB DRW 324K
2001 CCLB DRW 319K
Dp tuner infinity, exhaust, intake, chipped, tricked, and wrecked


Quote:
Originally Posted by marine5811
The stock downpipe in an OBS is flat because I'm a ginger.
Quote:
Originally Posted by alberta 7.3
Finding a decent woman is like shopping for a used truck. You spend most of your time picking through the money pits, wrecks, and basket cases until you find one that you can tolerate
Quote:
Originally Posted by JJFLASH
Well at least you caught the loose bolts before they cause any damage. Nothing worse than a sloppy hole
351fifty is offline  
post #5 of 9 Old 03-25-2013, 09:43 PM Thread Starter
Compression Ignition Addict
 
jmsmith76's Avatar
 
Join Date: Sep 2009
Location: Middle GA
Posts: 1,480
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 4
Thanked 9 Times in 7 Posts
Feedback Score: 0 reviews
Yeah I have access to a trailer. Think that'll put enough load on it to notice a difference?
jmsmith76 is offline  
post #6 of 9 Old 03-25-2013, 09:47 PM
DERAIL MOD!!!


 
351fifty's Avatar
 
Join Date: May 2011
Location: Canton and kennesaw
Posts: 23,174
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 34
Thanked 205 Times in 193 Posts
Feedback Score: 4 reviews
Does you problem only happen with head lights or park lamps? Kause a trailer's park lamps combined with yours should draw about as much as the headlights, that and electric brakes as well

-Kris-
2011 f150 ecoboost 4x4 323/452 on php dyno 11/16/13
1995 CCLB DRW 324K
2001 CCLB DRW 319K
Dp tuner infinity, exhaust, intake, chipped, tricked, and wrecked


Quote:
Originally Posted by marine5811
The stock downpipe in an OBS is flat because I'm a ginger.
Quote:
Originally Posted by alberta 7.3
Finding a decent woman is like shopping for a used truck. You spend most of your time picking through the money pits, wrecks, and basket cases until you find one that you can tolerate
Quote:
Originally Posted by JJFLASH
Well at least you caught the loose bolts before they cause any damage. Nothing worse than a sloppy hole
351fifty is offline  
post #7 of 9 Old 03-26-2013, 06:18 AM Thread Starter
Compression Ignition Addict
 
jmsmith76's Avatar
 
Join Date: Sep 2009
Location: Middle GA
Posts: 1,480
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 4
Thanked 9 Times in 7 Posts
Feedback Score: 0 reviews
Ok, I'll hook it up today during lunch break or after work and see what happens.
jmsmith76 is offline  
post #8 of 9 Old 03-26-2013, 08:35 AM
DERAIL MOD!!!


 
351fifty's Avatar
 
Join Date: May 2011
Location: Canton and kennesaw
Posts: 23,174
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 34
Thanked 205 Times in 193 Posts
Feedback Score: 4 reviews
Don't need to be hitched, just plug it in and try it

-Kris-
2011 f150 ecoboost 4x4 323/452 on php dyno 11/16/13
1995 CCLB DRW 324K
2001 CCLB DRW 319K
Dp tuner infinity, exhaust, intake, chipped, tricked, and wrecked


Quote:
Originally Posted by marine5811
The stock downpipe in an OBS is flat because I'm a ginger.
Quote:
Originally Posted by alberta 7.3
Finding a decent woman is like shopping for a used truck. You spend most of your time picking through the money pits, wrecks, and basket cases until you find one that you can tolerate
Quote:
Originally Posted by JJFLASH
Well at least you caught the loose bolts before they cause any damage. Nothing worse than a sloppy hole
351fifty is offline  
post #9 of 9 Old 03-26-2013, 10:42 AM Thread Starter
Compression Ignition Addict
 
jmsmith76's Avatar
 
Join Date: Sep 2009
Location: Middle GA
Posts: 1,480
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 4
Thanked 9 Times in 7 Posts
Feedback Score: 0 reviews
What? Really? I thought the ball had to be hooked and secured for the lights to work.

Tested it out a few minutes ago. Here are the results:

Idling, no load: 14.0-14.2
Idling, headlights: 12.5-13.0
Idling, running lights w/ trailer plugged in: 13.2-13.5
Idling, running lights & brakes w/ trailer: 13.0-13.3
Driving, no matter what the load is: 14.0-14.2

Basically I would just let the alternator be at full voltage, then cut running lights/headlights/brakes/whatever else on and it would drop down to somewhere in the above ranges depending on what I had. Charges fine under load while driving. I'm thinking it's just a bad alternator unless you can think of something else that would cause the same conditions. I suspected bad alternator in the first place, just would hate to swap it out again and it not be bad.
jmsmith76 is offline  
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:
OR

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
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



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

 
For the best viewing experience please update your browser to Google Chrome