Ambient outside air temp is bottom of the passenger side mirror. Unless they're using the BMS shunt processor on the negative battery post. More indicative of battery temp.
Bottom of the outside mirror... Well how about that! I suspect that is the one in use by Ford in their programming of system voltage and would explain the wintertime voltages I've seen. If you look back at a post I've put up, there is a formula for float voltage versus temperature. The system voltages appear to follow that with the exception of the voltages I've seen for the deep winter with a fully warmed up engine compartment. Those voltages just stayed high as if the warmup had not occurred. That really confused the issue for me. My conclusion now is that Ford programmed the system voltages right along classic battery charging and floating lines. I've remarked that one should look out into the truck from the battery instead of looking into the battery from the computer. This then leads me back to my conclusion that Ford OEM Batteries are/were defective in some way. My experience was simple: had some weird readings 4 months after delivery, replaced the battery with a Non-Ford battery (NAPA off the shelf) and have had zero weird things since.
Unfortunately you don't get off that easy. Communication is done via LIN bus. No PWM/Voltage sense modification for you. Given the latest rounds of software updates, the forscan set point seems to be alive based on reports. IF the new BMS logic was OTA'd to you AND you have forscan, change your SOC set point to 95% or so.
Not per the manual. When it says LIN it's LIN. There's likely diagnostics data on there as well, not just voltage command. Even the battery shunt communicates on LIN bus.
Be careful. You can recharge a battery too fast and this kind of battery is more susceptible to overcharging. In a flooded cell battery there's a relationship called "Temperature-Voltage-Gassing." The purpose is to limit the amount of current when the battery charge is above about 70% so that the gassing won't cause spalling off of active material. These AGM batteries are likely less susceptible to this because they've got thinner plates. Still if you're manually controlling things you can get distracted and so on. Also if there's a big change on the busses, you may not react quickly enough and something might get damaged.Glad you found it.
Maybe someone can help "me" find something. Which module, connector & wire color does the "Gencom" signal use, going to the alternator? I think it should be the center wire of the alternator's 3-wire connector, possibly an "RC" signal on the alternator?
I plan to conveniently switch the alternator side of this soon to be "cut wire", between it's original connection (factory PWM source), and a PWM module (pic below) that I manually adjust the duty Cycle of the selected 100hz signal. This will allow me to dial up any steady alternator output voltage, driving and accelerating any charge current within reasonable limits. This will prove useful for cold weather and short trips. The BMS will still tally up the ramped-up Amp-hours, show charge-current, etc., but also allow me to not worry about adding enough loads to keep charge-mode from going into "Fast Regen". It will also allow me to charge with a few more amps, speeding up the process. Not that I'm trying to charge fast, but how rediculous is driving for hours at 1 amp or less, when clearly there are way more Amp-hours to replace! $12
And a 3-position (center off) toggle switch, placed in center position should simulate unplugging the alternators 3-wire connector, placing it in "dumb mode" with a steady 13.8V, regardless of rpm, the way alternators used to work.
Thanks Bill. Like I mentioned, I don't want to charge fast, I just want to make the most of sometimes short errands and not trickle at 1 amp. 200 amps at my disposal and don't charge as well as a battery tender sometimes does. More importantly, I want to stop the battery discharging 10-30 amps when rolling to a stoplight. This brief minute or less negates quite a few miles of 1 or 2 amp trickling while driving. Granted when I take back off the battery accepts 10 or so amps for a brief few seconds until tapering back down to an amp or 2. How can they build a charging system that "loses ground" so easily?
Did you wake it up (have key in pocket)? Waking it up starts eating juice. Curious if your measurements include disturbing it w/ keyfob on your person or the hood is up and key inside. You will get varying results w/ the key on you. The kids get a kick out of the welcome lighting. "whys it do that?" - "It's my dog - it's happy to see me" Tell it it's a good boy, hit the lock button in my pocket and the lights flash "see he understands me"
