Return of the 12 volt Gremlin?

[Ragman]

Seemed like Ford had fixed this issue but might be back - went to start Lariat and it did the 99 warnings, frunk open, yadda yadda... no start, screen shutting down low power.

Truck was plugged on Level 2 at 95% for past 48 hours, last trip was 200 miles. Temps getting cool here but above freezing.

12 volt is "newish" replaced under warranty back in spring - tested weak at tire change.

No logical reason for it to have been too low to engage contactors. Only thing I can think of was potentially an overnight update drained it?

5 seconds on power pack and it "started" though powertrain error stayed for a day before clearing.

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[The Weatherman]

 

[Aminorjourney]

I had mine do something similar on Friday.

However, I unlocked the truck on Thursday and fitted a new dog cover for the rear seats, and had the doors open for a while. I never turned the truck on.

I wonder if there's a bug where the truck doesn't go back to sleep...

 

[chl]

Why I put a connection for a trickle charger inside my charge port in case the 12v battery gets too low to open frunk and access the battery or the jump 'pins':

Lead acid batteries prefer to be fully charged for long life.

PS: attached to battery terminals - the negative connection downstream of the BMS, but if could be attached to any body ground point.

Attached at blue circles, NOT red X's.

The 6mm terminals had enough spare room on the top to put ring connectors and a 6mm nut.

This is equivalent to the item I used for the connection (with a 5ft cable):

It is fused in case.

https://www.amazon.com/dp/B0FD31WBF...afb7&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWwy&th=1

I made my own from old wires from a couple old trickle chargers extra parts. Just be sure to include a fuse, don't want a 12v battery short caused fire!

Hard to make out in the image of the next peak trickle charger but the "trickle" LED on the far right is lit.

 

[Adventureboy]

Having the truck plugged in for 48 hours doesn't help the 12v battery, unfortunately. The truck only charges the 12v while actively charging the HVB, so once the HVB gets to target SOC, the 12v is left to discharge even while plugged in.

The truck "should" charge the 12v when it drops to about 40% SOC, but I have found that sometimes this process gets disrupted or cancelled with various events like doors open or ajar, driveway shuffle at the wrong time etc., and then the 12v drains.

If you've had to replace your 12v battery already once, you may be like me, and your driving habits cause a challenge for the 12v charge cycle. In my case, I didn't drive daily and had to do driveway shuffles to let the wife out of the garage. This caused all kinds of 12v issues and messages, so as others have suggested, the 12v battery maintainer solved my issue if I wasn't driving for a day or two. I permanently installed a 5 amp NOCO on the back of the 12v access hatch door with a 120v RV power port in the air dam so I could plug it in easily with a normal extension cord.

It is frustrating to have to plug in the trickle charger every couple of days on a premium truck with a 131 kW battery that can run my house for days, but isn't smart enough to keep its own 35Ah 12V battery healthy.

 

[chl]

I am now using a 1A NOCO, the first NOCO I bought just sat there pulsing red, but the replacement works fine so far.

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