Back in the middle of November 2014 I went to start up my truck one morning only to find low voltage batteries (~10V). I was a little taken back by this as I replaced both batteries back in February of 2014. Ended up buying a Diehard battery charger to slow charge the batteries up to voltage. I monitored my battery voltage, FICM voltage and did not notice any out of the normal.

Toward the beginning of December, again I went out to start the truck to only have low battery voltage (~10V). I charged up the batteries and looked at the battery voltage and FICM voltage after the charge. Nothing out of the ordinary. I also took a 400 mile trip and watched my battery voltage, it remained at 13.4V as I drove.

About two weeks ago, I went to start the truck and it was a slow crank to get it to start. Except this time upon looking at my Torque app, the battery voltage after 5 minutes of running was only 11.4V. It did not go higher than 11.5V. As I limped the truck home it went down to 11V. I charged the batteries again and then two days later the same condition happened. The battery voltage did not get above 11.5V after running for several minutes. Basically the alternator was not outputting anything higher than the charged battery voltage. I limped my truck home and it was not happy running on just the batteries (lights flickering, truck surging, etc.) and it freaked me out.

Started looking into the options to replace/repair an alternator. After looking online, it appears that the 6G is poorly designed. Reading forums on alternator replacement revealed 6.0L owners frequently swapping out OEM alternators. Wasn't common for an OEM alternator replacement every 50K. Looked into rebuilding but found that it was going to be challenging to source high quality rebuild parts (on top of not knowing what parts would work to produce a quality rebuild).

Ended up considering an OEM replacement, OEM remanufactured or the Ford-Truck forum DC Power alternator favorite. I decided on the 190 amp DC Power alternator from Ed at FICMrepair.com. I ordered this alternator mid-week, and arrive by the end of the week. I installed it this past weekend (one foot, literally, on the old alternator and the other foot on the passenger side wheel and with a third arm) and set the latch on the belt tensioner. That Ron must have a good pull because it took all 170lbs of pull I could generate to get the latch set. The alternator is in.







I'm not sure what I could take away from noticing the early slow or no starts from low battery voltage. I watched the output on my Torque app and didn't see anything obvious. Only until late week did it become obvious that the alternator was not outputting and needed replacement.

 

So do I understand correctly

You got a new Dc 190 amp alt and newer batteries but still having problems?????


If so time to look into the ground cables and we could troubleshoot the charge system

What is the voltage you are seeing upon startup now

 

Do you have a dvm

Digital Volt Meter

You can check cables for continuity they also need to pass a load test

There is a great pinpoint test on here somewhere it might be in tech folder


Also post you voltage at startup at idle and at high idle

Is your battery light on dash on

 

Blade35 I am not having any more issues. After installing the new DC alternator my battery voltage is now at 14.4V after 2 minutes of running. The FICM main power is 48-49V and the FICM logic power is maintaining the same voltage as the battery.

So far, so good.

 

Oh great problem solved

 

Personally I would look at getting a little more clearance between the CAC tube and the alternator.
Just me tho.