New motorcraft batteries from ford dealer installed approx 3 years ago, voltage all checked out fine

Ficm was dying roughly 6 months ago, replaced and checking voltage, everything at that time checked out fine. ScanguageII modified to keep a closer eye on ficm volts, stays at 48 all the time.

Decided to have the egr cooler bulletproofed, blue spring kit installed, water pump upgraded to billet, and a new oil cooler installed as my deltas had climbed just a tad indicating to me that the cooler was begining to plug. Also purchased a carb compliant tuner (sucks to be a Californian sometimes), wanting to run a very mild tune for mpg increase (grumble grumble, politicians!!).

All that being said leads me to this, installed the SCT tuner and got it all set up, for whatever reason it will not load the tune on my truck as it keeps erroring out when writing the TCM code. Spoke to the guy who had done the work (very reputable) and he came out to see if he could give it a go etc etc. It failed again, then after reloading the old factory data back, started the truck up and man the batteries were low after all the key on key off stuff. Let the truck run a while as the mechanic assumed if the batteries were low its probably whats been giving the tuner fits, so after about 30 mins running we tried again and blah still errors out...once we get the truck running again (reloading oe tune) i start the process of setting up all the gauges i want to monitor, and i notice the battery voltage is low...11.8 at that moment. Upped the rpms a bit and the voltage does go up, but never really goes past 13.2 and its only there briefly. Drove the truck home (45 min drive on the freeway) and im really watching the gauges now and its mostly staying 12.4 to 13.2. I am aware that different gauges are going to have differing tollerances, and i cant recall what the SC2's numbers were as it only has 4 things to monitor and battery volatge was taken off in favor of the ficm voltage but when i did the FICM it was dead on 14. I no longer have access to the testing equipment that I did prior too so i cant repeate the tests to see if i get the same data, and I do not trust autozone to know what they are doing (im sure there are good ones but who knows what you get when you walk in the door).

So i thought id reach out and see what you guys think...bad batteries? Bad alternator? Both going bad? Or just new gauge is reading different and I need to adjust? Truck goes in for suspension work tomorrow for a few days but this is going to drive me bonkers until i know what needs to be done...im worried my baby has a booboo

For reference
2006 Ford F350 4x4 XLT 73000 miles on it

 

Disconnect the batteries, put them on a charger overnight. Remove the charger let them sit for an hour and check the voltage with a DMM. They should read 12.6 or better volts.
Take them to an auto parts store that does load testing and have them checked.
With batteries installed, start the engine, wait a couple minutes and using a DMM check the voltage at the batteries. 13.5 or more is adequate to keep them charged. If it is less the charging system is suspect.

 

Batteries were a little low and are being charged up, still waiting for the results back on the alternator. I am assuming it’s dying and needs to be replaced, so I started looking and man there’s literally hundreds to choose from...anywhere from the cheap reman at like 90 to 800+ fancy billet heavy duty ones. What’s the consensus alternator I should be looking at?

 

The minimum I would consider is a quality 140 amp alternator with an overdrive pulley installed. If you have a lot of accessories and/or do regular short trips then I would go bigger. Good Luck, Russ

 

Ok so the plot thickens. At the alternator I’m 13.9...edge at idle shows 12.5-12.9. Batteries were a little low but charge up fine and test good. Thoughts?

 

I do have an after market stereo (just the head unit no amps) and I run the edge monitor also so I don’t think I’m drawing a ton of juice but my typical drive time is short...5-10 minute round trips to the store. Work is 3 blocks from the house. I actually have to be cognizant of making sure to take detours a lt least once a week to allow it to fully warm up and stretch out.

 

upgrade to a 240 amp alt from Ed's FICM and get the upgrade wire kit also , my volt never drop below 12.9 and that's with the glow plugs on

 

No offense intended, but I don't take my 6.0 out unless it is going to get good and warm - doesn't have to be a work-it-hard thing, but these 6.0s just die in grocery getter duty... First time my turbo vgt stuck was when my wife had it hooked up to the horse trailer for a month and did only local rides...

My experience, but I think pretty much all the HD light pick up diesels need to get run...

 

I have the DC Power Systems 250amp alternator and the Ed’s FICM battery cable upgrade. My alternator at idle is regulated to 14.5 to 15.0 vdc. And it is the same at my batteries and my SCT X4 tuner indicates the same.

I would suggest that you throughly clean the battery connections, coat the battery post with dielectric grease (prevents corrosion) and make sure the connections are tight. Next check and clean the ground cables where they connect to the motor or chassis. There should not be a 1vdc difference between the alternator output and your edge tuner. Get a DMM and connect the negative lead to ground and don’t move it. Now measure the alternator output and the battery voltage at idle. Should be the same.

Ed

 

First, double-check your voltmeter; I've been down that path with a member. If you are by or going to someplace that sells batteries, check it against batteries on the shelf, which typically are 12.6 to 12.8v.

As Ed mentioned, if you have a 1.0v difference, you got an issue. Typically the worst case is 0.5v. All the grounds and positives need to be cleaned.

Check the alternator voltage between the positive alternator post and the alternator case, eliminating any ground connection issues. it doesn't eliminate any sense wire issues. And check it after 3 minutes of starting a cold, so the glow plugs and alternator regulator thermistor do not influence the output.

I've got a long-winded video on YouTube about all the grounding connections. And do not forget about the two connections to each battery positive post.

 

Listen to TMT aka Jack, he is the MAN when it comes to this issue.

 

Truck is in the shop today getting looked at, as I'm concerned my equipment is old and no longer accurate. This morning when I started her up everything looked fine...Edge is reading between 13.6 and 14...im almost positive I've got a loose connection somewhere, time to go at it like a spider monkey armed with a ratchet . And yeah I'm a clean freak, my battery posts and clamps are spotless and those are for sure tight....have not chased them all the way down though...50:1 somethings not quite tight enough after having the egr and oil coolers done.

Thanks for the tips, idk why I didn't go for that right from the start...sometimes having other people who aren't stressed off their baby having a booboo provides enough clarity Will let you know what I find