Coyote Five O

Just wondering if anyone has a diagram for this.
Im interested to see if anything is connected to the voltage sensing wire Fuse Slot #38 "Alt A Sensor"which runs to the voltage regulator..

I may instal a diode on that wire to increase charge voltage to keep my larger Northstar AGM 94R properly charged, the stock charging voltage is a little low for what the Northstar needs.
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Thanks

stormsearch

Yes, that line is connected to the PDB power supply. That provides reference voltage back to the Alternator regulator. Note, if the PCM commanded voltage is much different than actual voltage, there will be warnings on IP.

52merc

Here is the wiring for 2016. "A" is from BJB Fuse-38. "B" is from High Current BJB MEGA 300A fuse.
If your truck has a 5.0L, it would have come from the factory with a conventional flooded lead acid SLI battery. When you switched to the AGM, did you change the BMS parameters? If not, you can increase the charging voltage by changing the BMS parameters for the AGM battery which requires higher charging voltage than a FLA battery. Original BCM PID should be 726-04-01 0EXX XXXX XXZZ. I suggest changing it to 726-04-01 02XX XXXX XXZZ which it for a large size AGM battery. These changes can be made with FORScan along with a BMS reset if that was not performed when then new battery was installed.
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Coyote Five O

excellent thanks for the info & diagram
funny it did come with an agm battery, the stock battery was smaller ( group 48 ) i installed the slightly larger 94R but it just needs more voltage, the truck is only keeping it at 70% SOC, charge voltage is 4.2-4.6, float is around 13.0-13.5.
this new battery needs 14.7 for charging and 13.62 float.
wonder how much fine tuning forscan would allow, im assuming its already set to charge an AGM, gonna trend some voltages for a better reference.

any idea what the alternators charge voltage should be when set to "Large AGM" ?

plopping a 1amp diode seems to easy, that would also raise the charge voltage .5V which is a bit much, i just need .2-.4ish & the diode of course isnt tunable.

​​​​​i'll have to dig a bit deeper

cheers for now

52merc

The BCM PID 726-04-01 was set at the factory for the smaller capacity battery (726-04-01 01XX XXXX XXZZ). It you change it to the value I suggested before (726-04-01 02XX XXXX XXZZ) then it should increase the SOC level because it finally knows that there is a larger capacity battery. Charging voltage alone is not the only factor involved with the BMS controlling SOC.

I'm not sure what will actually happen if you add your diode. The algorithms used by the BMS are apparently fairly complex and my knowledge is limited. PM "stormsearch" and he might be able to help you out. He is a Ford engineer that works in that area.

stormsearch

Charging voltage profiles do differ between SLI and AGM batteries. To ensure to get a better charge profile, follow 52merc suggestion and be sure the BCM has the right battery type selected. The OEM battery for the vehicle stated in your profile was an SLI. In addition, since the battery is fairly new, do the BMS reset.

Though will obtain a better charge profile by ensuring AGM is selected in the BCM, the charge voltage is based on battery temperature. The BCM has an algorithm that estimates battery temperature. There is no setting in the BCM for charging voltage. There is no "charge" or "float", it is based on simply the battery temperature algorithm. A question would arise then why when first start in summer seeing high voltage? Remember, it is based on an algorithm that uses other vehicle parameters, engine temperature environmnet will be considered cold for first start up. I cannot provide the parameters used to determine the algorithm as they are not public information. It is common to see low to mid 14 charge voltage until engine ennvironment obtains operating temperature, then charge voltage will decrease.

Adding a diode with the standard 0.7v drop, might increase it enough for your satisfaction. Be prepared for Charging System warnings on the dash, DTC and battery light. The BCM sends command voltage to the PCM which then commands the alternator. If the PCM sees a different charging voltage vs. command, be prepared for some issues.

Coyote Five O

Thanks again for all the info
I ordered a OBDII-USB adapter, will have a look in Forscan when it arrives.

Coyote Five O

My OBD Adapter cable arrived
Setup Forscan & saved all stock modules, the battery profile was set for a much smaller battery, changed it to "Large AGM" then did a BMS reset as 52Merc suggested.
We'll see what that does i, I also noticed a bunch more BMS settings in the BCM, a couple that caught my eye were "BMS SOC Max Cfg" and "BMS Target SOC Cfg"
On the first startup after changes my voltage jumped up to 14.9-14.91 for 10 mins idling then i pulled out and drove around for 20 mins, the voltage stayed up at 14.9-15v for at least 6-7 more minuted then fell to 13.4 finally, the 14.9+ seemed to last longer than i would like ( wouldnt wanna cook my battery ), i will chalk it up as the truck trying to relearn the new battery capacity & ability to take a charge. Definitively dont think i'll be needing a diode anymore, i'll see how it goes over the next week, i have a bluetooth battery voltage monitor connected & trending the voltage 24/7 so will get a good look at the charging algorithm and my SOC.

One thing kinda bugging me is Forscan is finding a 3.5L Ecoboost Turbo as the only profile even though i have the 5.0L V8 ? is this common ?
I deleted the profile, disconnected Forscan, reconnected and it came back as Ecoboost 3.5L , renamed it 5.0L V8 and it still comes up as Ecoboost when i connect Forscan ?
Cant figure that one out ?

Coyote Five O

Well this isnt working very well
my OCV is sitting around 12.6-12.7v
It should be 13.0v ( i would settle for 12.9 or even 12.85v) for 100% SOC.
I have 2 Odyssey PC1500 in my boat and showed my Suzuki outboard charging voltage trend which was contantly @ 14.7v and they told me it is "Perfect" , those batteries are going on 7 yrs now and hold a OCV of 12.8 after sitting for 24 hrs.

Norstar also requires a high charging voltage, they said in an automotive environment 14.6-14.75v for MOST of my driving time.

Now that i have set the BCM to "Large AGM" i usually only see 14.1 on startup for a couple mins then it flucuates from 12.7 ( alternator totally shut down ?) to 13.2v...

so pretty dissapointed , i may try a few of the other battery type settings for forscan.
i had hoped for better results since my first drive after BMS reset saw 14.9v for at least 10-15 mins or so ( cant remember exactly but i was actually worried about it being too high)

I may need to start another thread, wish i could set the "Target SOC" in Forscan.
Bummer this beast of a battery isnt going to last long without sufficient charging.

RLXXI

You've fallen victim to the BMS. Look at your battery negative cable. See that inductive ring a few inches away? Unplug it and the pcm will no longer control alt output and charge as they have for the past 75 years. Disconnected mine about 6 years ago and all my battery troubles went away.

If the pcm can't see the battery state of charge it defaults to always charge. No it will not set a check engine light or any other warning.