Adventureboy
Well-known member
This has been covered.
Leaving your truck plugged in to the EVSE does not "trickle charge" your 12V battery.
Your 12V battery starts discharging the moment you stop driving the truck and by 0100 in the morning you can be assured that it will be below the 80% state-of-charge threshold needed for the update logic to process an OTA.
By 0700 in the morning it's likely more like 45-50% SOC.
Once the 12V battery drops to 40% SOC an internal timer starts and after 48Hrs the system will then charge the 12V battery back up to 80% (using either the EVSE or charge from the HV battery through the DCDC converter).
If at anytime the 12V battery drops to 30% SOC the system will immediately initiate a charge of the 12V battery back up to 80% SOC (using either the EVSE or charge from the HV battery through the DCDC converter).
Driving it for a half-hour recharges your 12V battery back up above 80% so the update logic will allow the OTA to process.
It's analogous to starting an ICE vehicle and letting the alternator recharge the 12V battery back up.
Why anybody would think that having updates process at Ford's default time of 0100 when the 12V battery is virtually never going to be at the required state of charge after all that's been written about this is a mystery.
Set your schedule to check about 15 minutes into your normal daily commute either to or from work and you'll have far more success with OTAs.
Thanks for the detail Mike G. It is very helpful to understand how this works. I am hoping Ford does keep an eye on the forums.
If the truck is discharging the 12V Advanced Glass Mat battery to 45-50% SOC overnight on a daily basis, the longevity of this battery will be severely diminished. AGM batteries are not designed for this kind of daily repeated depletion (especially down to 30% or 40% SOC), hence why so many of us are having problems with this. I see many warranty replacements of the LVB in Ford's future if this is truly the case.
It is a simple fix that Ford can apply as a software update and eliminate the dozens of low-voltage 12v battery messages we get along with the missed updates. If the truck is plugged in and charging the HVB, take the LVB up to 100% SOC - That's where our 12v AGMs will live a long and happy life. It makes no sense that the 12v AGM battery would be depleting while the HVB is being charged given the truck has a HVB to LVB charger onboard and has the smarts to charge the LVB when it gets low. Installing aftermarket battery maintainers that need to be plugged in separately on a $100,000 truck to get through a day is simply a miss by Ford given most of us charge the HVB daily. All that power - no way to use it.
I love my Lightning and there is no other truck I'd rather be driving right now. I hope T3 fixes this miss.
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