Another Alternator - Diesel Forum - TheDieselStop.com
6.0L Power Stroke Engine and Drivetrain Discussion of the 6.0L Power Stroke diesel engine and drivetrain in the 2003-Up Super Duties and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 6.0L Power Stroke engine.

 1Likes
  • 1 Post By TKOPerformance
 
LinkBack Thread Tools Display Modes
post #1 of 4 (permalink) Old 02-06-2017, 10:04 AM Thread Starter
Junior Member
 
Join Date: Jan 2017
Posts: 5
My Photos: (0)
Feedback Score: 0 reviews
Another Alternator

I just replaced my FICM, batteries, and alternator about a month ago and this morning the voltage reading on my scan gauge dropped from 13+ to 11.9-12. Then it stayed at 11.9 and the battery light came on. Am I seriously going to have to replace the alternator again? What would cause this to happen?
russmon06 is offline  
Sponsored Links
Advertisement
 
post #2 of 4 (permalink) Old 02-06-2017, 05:54 PM
Senior Member
 
Join Date: Jul 2007
Location: Delaware
Posts: 5,125
My Photos: (0)
Feedback Score: 0 reviews
That's not likely the alternator causing that. You're seeing battery drawdown from the GPs. I'd put my money on one or more batteries being weak. If you're putting out 13.5-14V going down the road once its warmed up the alternator is doing its job.

'06 F250 4x4 - 5" Flo Pro exhaust, SB Filter intake, Accufab elbow, Edge Evolution (monitoring only), SCT w/ ID custom tune, FASS 195 pump, Gillette Diesel EGR cooler delete, Sinister Diesel coolant filter, ELC coolant, updated turbo drain tube/oil feed line/STC fitting/oil cooler, ARPs w/OEM HGs, Elite coolant lines, ITP RR fuel system, RCD 175/30 injectors, Powermax, BD CCV, FICM.com FICM w/ ID tune, Elite UP, BPD water pump - 13.069 @ 101.94

'02 WRX - Outback rear disc swap, EBC green pads, DBA pillar vane rotors, TXS UP/TBE/TMIC, Perrin LW crank pulley, PPG billet steel shift forks, ACT Streetlite flywheel & clutch, K&N filter, STi Group N motor/trans mounts, TiC/Kartboy rear diff mounts/subframe lock bolts/outrigger stiffeners, Kartboy SS & all shifter bushings, custom PDX tune for Cobb AP - went 14.1 on a terrible 60ft before most of these mods; shooting for 13.50s
TKOPerformance is offline  
post #3 of 4 (permalink) Old 02-07-2017, 09:11 AM Thread Starter
Junior Member
 
Join Date: Jan 2017
Posts: 5
My Photos: (0)
Feedback Score: 0 reviews
Thank you for the reply, but did you read the post? "The voltage reading on my scan gauge dropped from 13+ to 11.9-12." Indicating that the alternator was out. I had the alternator bench tested and it was indeed bad. My question is what would cause it to go bad in less than a month? By the way how much money were you putting down? haha
russmon06 is offline  
Sponsored Links
Advertisement
 
post #4 of 4 (permalink) Old 02-07-2017, 10:37 AM
Senior Member
 
Join Date: Jul 2007
Location: Delaware
Posts: 5,125
My Photos: (0)
Feedback Score: 0 reviews
Yes, I read it, but you are misunderstanding what you are seeing. The amp load when starting a 6.0 and while the GPs are lit, which is for several minutes after starting, is extremely high. It is too high for a stock output alternator to fill the void created by the drawdown of the batteries. So what you are seeing is the load draw the batteries down to a degree for which the alternator cannot compensate. Once the GPs go out the alternator can fully recharge the batteries, which is why you see the reading go back up. A weak battery exacerbates this effect.

This is why 6.0s seem to go through batteries much faster than other vehicles. My stock batteries lasted all of two years. I then switched to Interstate Megatron II batteries from which I typically get 5 years. My stock alternator has 194k on it and still does the job.

An option is to swap in a higher output alternator like one from DC Power, but they are spendy ($300+).

Still another option is to upgrade the charging cabling from that alternator by adding a 1 gauge wire from the charging post to the + terminal on the RH battery, and add a 1 gauge ground from the alternator case to the chassis ground lug on the crossmember. I did that upgrade about 74k ago.
TurboThrill likes this.

'06 F250 4x4 - 5" Flo Pro exhaust, SB Filter intake, Accufab elbow, Edge Evolution (monitoring only), SCT w/ ID custom tune, FASS 195 pump, Gillette Diesel EGR cooler delete, Sinister Diesel coolant filter, ELC coolant, updated turbo drain tube/oil feed line/STC fitting/oil cooler, ARPs w/OEM HGs, Elite coolant lines, ITP RR fuel system, RCD 175/30 injectors, Powermax, BD CCV, FICM.com FICM w/ ID tune, Elite UP, BPD water pump - 13.069 @ 101.94

'02 WRX - Outback rear disc swap, EBC green pads, DBA pillar vane rotors, TXS UP/TBE/TMIC, Perrin LW crank pulley, PPG billet steel shift forks, ACT Streetlite flywheel & clutch, K&N filter, STi Group N motor/trans mounts, TiC/Kartboy rear diff mounts/subframe lock bolts/outrigger stiffeners, Kartboy SS & all shifter bushings, custom PDX tune for Cobb AP - went 14.1 on a terrible 60ft before most of these mods; shooting for 13.50s
TKOPerformance is offline  
Sponsored Links
Advertisement
 
Reply

  Diesel Forum - TheDieselStop.com > 1999-2007 Ford Super Duties > 6.0L Power Stroke Engine and Drivetrain

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Diesel Forum - TheDieselStop.com 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











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
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