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The lower reading in the SG is the screwy way it and the PCM reports voltage, although there is some issues that will come out in another vid.
For another vid I still have to publish, alternators, I too too readings at different loads.
That L-N voltage readout calms down in short order, it's just excited to be throwing electrons through the negative side to the batteries while they accept them at a high rate early on. That vid actually was recorded for 12 minutes to show that the batteries do not take the high rate of current that many cable up for, and in responce to a thread last winter of a member who only drove short distances so needed to get the batteries up fast.
That L-N voltage readout calms down in short order, it's just excited to be throwing electrons through the negative side to the batteries while they accept them at a high rate early on..
I wonder if AGM batteries are perhaps more stable, especially if kept at a higher state of charge?
Y2K and Jack: appreciate all the analytics you are throwing at this!
Y2K: you had asked the question of operating parameters when the LN was throwing the 14.7s. Well here is my monkey wrench of data to add to your guys' pile:
I had done some data capture for Jack earlier in the year and went back to look at the files this morning. My Factory 140A High Output (same as upper of dual) running an overdrive pulley, as I believe Jack's LN is, will also put out 14.7s. WHEN COLD.
I did a couple of cold starts and a couple of hot, all accessories on after a good long trip. Both cases after everything has settled down on cold start I could see bounces as high as 14.7V. Yet when warm the highest I captured was 13.9V (makes sense). These were all at idle readings.
Different from SGII, Torque has a number of battery/ficm voltages, one of them named Voltage at Adapter -- I've always assumed that was the OBDII port, but maybe it is actually from the PCM. Anyway, of all the voltage PIDs I can capture, this one always reads the highest. I'm taking readings at 1/10th second intervals - way more accurate than these old eyes can follow a DVM, so I'm going with the one reading being actual Alt output...
Don't know if this helps you or not, but I thought I'd throw it out there as this is off a stock Ford Alternator...
Batteries are 4 year old Costcos and I keep them charging on a smart trickle charger anytime I'm not driving the truck for a few days...
I should have taken a screen shot tonight. My OBDII adapter voltage reads the lowest of all of the voltage PIDs. All of the other ones will read 14.0 or 13.8 (Control Module) and the adapter will read 12.8v. Just remember that I haven't updated any cables yet and I have the L-N 230Amp Alt.
Just a little FYI.
Any time you run voltage through a diode you will see
a slight drop in the voltage. Look up "Diode Drop" It varies
by type of diode but tends to be near 0.5V. You can also look it
up as "diode forward bias". That might account for the 0.5 loss
that the SGII shows Vs a reading with a DMM at the battery terminals.
It seems I found an improvement for those who see low or varying volts and working on finishing the video. A few people here have done the modification (some not intended to have it, but very good that it happened to get my butt into gear) have the same better results I've had for 6 months. I've also been told it also worked on the 7.3, although I have no way of testing that.
But for a 6.0, again some variation is how the PCM and monitors report the info.
First initial start with cold underhood, then hot underhood so voltage regulator backed down with the L-N. Most do not see this voltage off the monitor or the consistency from my observations from the forum. It's about an $18-20 fix for someone who doesn't have good wire making skills and stock on hand.
I watched the video, and saw Randy's video too, and noticed you guys are both measuring battery voltage with a doohickey plugged into the cigarette lighter.
Is the cig ligher really the actual battery voltage in your trucks?
It isn't on mine:
Measurements taken at the same time under the same circumstances after 7 minutes of idling to assure steady state voltage. The battery voltage toggled between 14.43 to 14.44, but the cig lighter remained steady at 14.31.
Nevertheless, that .13 voltage difference between the cig lighter and the battery itself is still greater than the .10 difference between the cig lighter and the PCM, measured at the same time. And when stacking the differences, there is a .23 voltage difference between the PCM and the battery, not just the .10 difference that is displayed at the cig lighter.
On the other hand, with the key off engine off, the voltage matches across the board. But with the key on engine running, there is definitely a difference between voltage measured at the cig lighter versus voltage measured at the battery itself. In my testing, that difference has remained consistent, in both occurrence (different days and temperatures) as well as in amount (deficit of voltage found at the cig lighter).
It's not perfect and were not trying to get a perfect measurement. And not inclined to tell the average guy to drive around with breakout box in the cab all day.
We all are going to have slightly different readings, especially for those of us in the rust belt compared to CA oxidation free vehicles.
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