Another example of 12V Battery causing bizarre issues.

[topher10]

I wanted to share my experience to help other owners who might face similar issues. Reading this forum informed me that the 12V is a common issue, and this knowledge helped me to not overreact when I saw all of the warnings. I almost called a tow truck…

TLDR is that the truck would not start and flashed multiple serious warnings, but the issue was a depleted 12v. Jump-starting resolved all issues.

For those who care about details, here is the timeline.

1. Returned from 5-day trip last night, and on arrival briefly moved the truck about 10 ft in the driveway to make room for cars. No issues.
2. Drove to a nearby grocery store that is less than 1 mile away this morning. No problems.
3. Coming back to the truck with groceries, the frunk failed to open normally from the key fob.
4. Truck wouldn't start properly, as it would not enter drive/ready mode, but only accessory mode with warnings:
   • "Steering assist fault. Service required."
   • "Frunk system fault. Service required."
   • Additional accessory mode and frunk open warnings.
   • The center screen showed a timer that would turn off after a minute or two.
5. Attempted troubleshooting by manually opening and closing the frunk, and also Cycling power (~10 minutes). I wasn’t very systematic, but the goal was to get the frunk closed cleanly to see if that would help. Plus, sometimes you can’t help but hit the button a few times and hope something changes. None of this worked.
6. Called wife to retrieve groceries.
7. Disconnected 12V battery for 3-5 minutes.
8. Reconnected battery - situation worsened with additional traction control and parking brake warnings. This was my first clue that maybe it was the 12v. Why would additional issues pop up with the truck just sitting there.
9. Prepared to leave the truck and walk home, and realized the locks would not work automatically. Consistent with my growing suspicion that it was the 12v battery. There were simply too many errors all at once for them all to be real.
10. Walked home, researched issue, returned in another car with jumper cables. After jumping, all warnings disappeared. Frunk operation initially strange but worked the second time. Hopeully I didn’t damage the latch mechanism.
11. Drove for 20 minutes and then parked in the driveway without issues.

I last charged the truck to 80% on May 2 (11 days ago) and drove it enough to get down to about 40% before our trip started on May 8. My guess is that the 12V battery lost charge while sitting, and the two very short drives after returning (10 feet and 1/2 mile) weren't enough to recharge it. Opening the frunk with the power off may have contributed to draining it further.

I'm now wondering if the 12V is going bad or if it just drained acutely. I'll test it today and again tomorrow morning. This experience makes me nervous about leaving the truck for extended periods (like at the airport). In the future I plan to let it charge for at least a bit before parking it for a long time. I was trying to let it sit at ~50%, but in doing so it means it went a long time since the last charge, although it had an ~20 min drive before being parked. Secondly, I will leave it on for a longer time once restarting it after a long sit. With gas cars I often avoid a rapid on/off, particularly if they have been sitting. It seems I should also take this approach with the Lightning.

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[topher10]

Just read this thread about resetting the BMS after disconnecting the 12V. I wonder if I should trickle charge the 12V and do the BMS reset when it's full.
https://www.f150lightningforum.com/...fix-a-problem-bms-learned-values-reset.15900/

Do you trickle charge via the charge/jump posts, or directly to the battery? Can you leave it all connected, or should I fully disconnect the battery?

 

[Kansan]

Some possible causes:

• 12v is going bad
• Truck is being awakened by the key fob and/or FordPass frequently. Every event results in the modules draining the battery. (I keep my fobs in a faraday pouch to prevent this.)
• It’s possible that an over-the-air update is draining the battery during installation.

I installed an ANCEL battery monitor on my 24 Flash. It provides great information about the 12v battery SOC including while the truck is off. I haven’t driven today - the blip at the end of the graph is the voltage drop from using the keypad to unlock the truck.

 

[TaxmanHog]

Do you trickle charge via the charge/jump posts, or directly to the battery? Can you leave it all connected, or should I fully disconnect the battery?

ALWAYS, use the designated posts if you're not certain about where on/near battery terminals to connect to, there is a BMS which needs to "sense" the charging current flow to properly measure the LVB (12v) state of charge, do not position your charger leads directly on the posts, they need to be before the BMS cable lug.

 

[nate002]

This is why I keep a charged jump starter in the truck. Heard too many stories like this and don’t want to be walking or towed.

 

[RickLightning]

Do not reset the BMS until the battery is fully charged. And, note that while a battery tender may indicate it's fully charged, it likely is not. It may take a few days to get there.

 

[SSNutz]

I have post this before...I was having weird errors, losing connection, and finally my truck was brick one day. It was all related to the 12v, LVB issues. Before my truck was "dead" I started to monitor the LVB heath with a OBD reader and CarScanner. I notice that my 12v battery was at times just fine, about 85% SOC. They it would be below 50%. So my thoughts to start looking into this issue and that weekend the truck would not start. Now I had truck for about 8 months now and tougt maybe a battery. Manually popped the frunk and to access the 12v battery. I grabbed the neg side wire to remove it and the truck came back to life...the dang neg wire was loose. 10 mm socket wrench and few turns and the truck was just fine. Never touch the battery before this time. Ok, fast forward two months later and have not had any errors, not loosing connection (Ford Pass), LVB SOC is usually in the 90% when I start up the truck, maybe in mid 80% if Sat for days.
From this experience I do two things differently:
1) Always will be mentoring LVB system. Highly recommend a OBD dongle and Carscanner(or similar) for wealth of information and error reading ability.
2) I have a EVSE that can adjusted amp output (thru the app) 8a to 48a. So I now adjust to a lower amp output (~16) so my truck will be charging much longer, almost like having a trickle charger on the 12v. This could be silly, but since I like to do small delta charging for the HVB (summer - 40 to 60; winter 50 to 70) for my normal daily commute needs. This slowed charging will max the charging for LVB. When extra energy is needed, bumped the EVSE up to 48a and charge to 100%.

Bottom line is the LVB need more love.

 

[Adventureboy]

Resetting the BMS will not likely help unless you install a new battery. The LVB does not like short trips or driveway shuffles. It lights up all of the modules and drains the LVB for the next 30 minutes until it shuts them back down. A few driveway shuffles or trips to the corner store, or leaving the Frunk open too long, or opening the doors too often without driving, will all cause the LVB to drain. If it is an undisturbed drain, the truck will charge the LVB from the HVB and it shuts down modules like the modem to conserve power so Fordpass won't work. If you disturb the "emergency" charging early in its cycle by a driveway shuffle or short trip to the grocery store, it is very possible the LVB will go dead.
This doesn't mean the LVB is bad, but rather the sequence of events depleted it. It is much more likely to happen if your LVB is already weak from repeated deep discharges.
Have your battery tested, and replace if weak. If you are doing a few short runs, consider leaving the truck running (ON with lights off) while you run your errands. The benefit is a nice warm/cool truck when you come back and the LVB has been charging while you shop. Don't forget to turn your lights back on.

Agree with @SSNutz post, however, be careful with OBD dongles. They can keep modules active and drain the LVB faster. I use a passive Bluetooth-enabled monitor.

 

[SSNutz]

Resetting the BMS will not likely help unless you install a new battery. The LVB does not like short trips or driveway shuffles. It lights up all of the modules and drains the LVB for the next 30 minutes until it shuts them back down. A few driveway shuffles or trips to the corner store, or leaving the Frunk open too long, or opening the doors too often without driving, will all cause the LVB to drain. If it is an undisturbed drain, the truck will charge the LVB from the HVB and it shuts down modules like the modem to conserve power so Fordpass won't work. If you disturb the "emergency" charging early in its cycle by a driveway shuffle or short trip to the grocery store, it is very possible the LVB will go dead.
This doesn't mean the LVB is bad, but rather the sequence of events depleted it. It is much more likely to happen if your LVB is already weak from repeated deep discharges.
Have your battery tested, and replace if weak. If you are doing a few short runs, consider leaving the truck running (ON with lights off) while you run your errands. The benefit is a nice warm/cool truck when you come back and the LVB has been charging while you shop. Don't forget to turn your lights back on.

Agree with @SSNutz post, however, be careful with OBD dongles. They can keep modules active and drain the LVB faster. I use a passive Bluetooth-enabled monitor.

Thanks for adding the comment about the passive Bluetooth-enabked monitor, this is key for leaving it installed.

 

[RetiredLightning]

Some possible causes:

• 12v is going bad
• Truck is being awakened by the key fob and/or FordPass frequently. Every event results in the modules draining the battery. (I keep my fobs in a faraday pouch to prevent this.)
• It’s possible that an over-the-air update is draining the battery during installation.

I installed an ANCEL battery monitor on my 24 Flash. It provides great information about the 12v battery SOC including while the truck is off. I haven’t driven today - the blip at the end of the graph is the voltage drop from using the keypad to unlock the truck.

Curious which Ancel model did you use?

 

[topher10]

Thanks for all the feedback. Thought I would give an update.

First, I used a multimeter to check the truck yesterday, and it was 13.5V while ON, and 12.5V while OFF, and 14.5V while OFF but plugged in. All seemed normal in terms of operation.

However, I had one more weird issue. I plugged it in last night about 10PM, with a my standard charge time of midnight to 8 AM. However, it had not charged this morning, even though the FordPass app showed that it was connected the entire time. Instead, charging started immediately when I interacted with it the truck. I decided to leave it charging and take the other car to work, and charging seems to have complieted normally. I will give it a drive when I get home.

Also considering an OBD2 monitor. I saw this one from a different thread, but it might be overkill for monitoring the LVB: https://www.amazon.com/OBDLink-Bluetooth-Professional-Grade-Diagnostic-Performance/dp/B07JFRFJG6. I have a cheaper one, but it only showes voltage, not SOC, so its not much better than my multimeter.

 

[richguy82]

I had kind of my first weird issue last Saturday morning where I wasn’t able to start my truck or change my departure time from the app. It was plugged in at the time. I didn’t see any updates that had been applied. It started up fine and I had a little highway trip to do, but I noticed all of the little noises (keep eyes on the road, hands on steering wheel, etc.) sounded different, almost harsh. When I arrived at my destination I noticed my Remote Start was shut off from the screen in the truck. This was why I was unable to control it from the app. No idea why. Car scanner said the state of LVB charge was 91%. I’m not sure what to make of what happened, but my first thought at the time was the 12V battery. Anyone have a similar issue? At any rate, I keep a combo air pump and jump starter in the truck at all times.

 

[TaxmanHog]

When I arrived at my destination I noticed my Remote Start was shut off from the screen in the truck. This was why I was unable to control it from the app. No idea why.

Mystery updates and general weirdness ?

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