DBC

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This is quite great news. Wonderful that the main battery will maintain the 12v. It always seemed ironic that you could have all these kWh available and not be able to use them because you couldn't start the car.
 

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When I saw the car on the Mach E tour earlier this month, the guy showing the car said they could not get into the car after it was stored over the holiday. I got the impression it was stored for a month and I don't think it was plugged in, so could not maintain the 12 V. He had to eventually figure out how to jump the 12 V to get in. Seems like if it's not plugged in, 12 V will drain quickly (especially in cold weather).
 

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I must be missing something here - If the 12V battery is maintained by the HV battery - suppose the HV battery goes dead for whatever reason, then the 12V battery goes dead. Why not just plug the car into a charger? Won't that start charging the HV battery, thus charging the 12V battery?
 


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I must be missing something here - If the 12V battery is maintained by the HV battery - suppose the HV battery goes dead for whatever reason, then the 12V battery goes dead. Why not just plug the car into a charger? Won't that start charging the HV battery, thus charging the 12V battery?
If the 12v battery is dead. The whole car is dead. Without power to the modules, the charging session will never initialize.
 

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It'll be interesting to see at which points the Mach-E does actually maintain the 12V battery. Most EVs maintain their 12V batteries, but not all the time.

I believe my i3 only maintains the 12V battery charge while the car is on and maybe while it's charging. If you let the car sit for an extended period, the 12V can definitely die.
 

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I must be missing something here - If the 12V battery is maintained by the HV battery - suppose the HV battery goes dead for whatever reason, then the 12V battery goes dead. Why not just plug the car into a charger? Won't that start charging the HV battery, thus charging the 12V battery?
The contactors for the HV battery are controlled by the 12V electrical system.
 

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When I saw the car on the Mach E tour earlier this month, the guy showing the car said they could not get into the car after it was stored over the holiday. I got the impression it was stored for a month and I don't think it was plugged in, so could not maintain the 12 V. He had to eventually figure out how to jump the 12 V to get in. Seems like if it's not plugged in, 12 V will drain quickly (especially in cold weather).
I think I know what Darren is talking about and assuming the system works as intended......then the 12v battery shouldn't ever go flat. It would take quite a perfect storm of events to drain that thing without any sort of warning.

However, real world reports tell a different story. There are reports of the pre-production cars experiencing flat 12v battery which is contrary to how the system is designed. Maybe those are isolated cases and a valid explanation exists but until we learn of those details.....I will remain somewhat skeptical and cautious.

According to the documentation I have read, the door latch modules have an energy storage feature that allows them to open the doors even with dead 12v battery. The question I have is how can a 'module' operate without the 12v battery? The secondary question is how does that module received it's signal to open? Will it open for anybody or only for an authorized person. How is that person authorized.

The system is nearly identical to the Lincoln Continental hardware. The difference there is the Lincoln has place for a key. The MME does not. Maybe the engineers at Ford came up with a super clever system. I would have just put a key cylinder in the rear liftgate.

I guess we will see what happens in real world situations.
 

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It'll be interesting to see at which points the Mach-E does actually maintain the 12V battery. Most EVs maintain their 12V batteries, but not all the time.

I believe my i3 only maintains the 12V battery charge while the car is on and maybe while it's charging. If you let the car sit for an extended period, the 12V can definitely die.
Here is an excerpt from the service manual. This appears to indicate the HVB is able to charge the LVB even when the vehicle is turned off and off plug. Do you read this the same way?

Ford Mustang Mach-E Darren Palmer talks Mach-E 12V battery and first OTA software update 1612145659228


And.....
Ford Mustang Mach-E Darren Palmer talks Mach-E 12V battery and first OTA software update 1612145778234
 

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I think I know what Darren is talking about and assuming the system works as intended......then the 12v battery shouldn't ever go flat. It would take quite a perfect storm of events to drain that thing without any sort of warning.

However, real world reports tell a different story. There are reports of the pre-production cars experiencing flat 12v battery which is contrary to how the system is designed. Maybe those are isolated cases and a valid explanation exists but until we learn of those details.....I will remain somewhat skeptical and cautious.

According to the documentation I have read, the door latch modules have an energy storage feature that allows them to open the doors even with dead 12v battery. The question I have is how can a 'module' operate without the 12v battery? The secondary question is how does that module received it's signal to open? Will it open for anybody or only for an authorized person. How is that person authorized.

The system is nearly identical to the Lincoln Continental hardware. The difference there is the Lincoln has place for a key. The MME does not. Maybe the engineers at Ford came up with a super clever system. I would have just put a key cylinder in the rear liftgate.

I guess we will see what happens in real world situations.
The strategy for keeping the 12v system charged with the main HV battery was not finalized until after the pre-prod cars were built.
 

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And since we are on the subject.....
The service manual talks a bit about those two wires in the front bumper. They only become viable when the 12v battery SOC falls below a certain threshold. If the 12v battery is operating normally.....then those two wires in the bumper are not functional.
 

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The strategy for keeping the 12v system charged with the main HV battery was not finalized until after the pre-prod cars were built.
Thanks. That explains the issue with pp vehicles then....

So, how does the door latch module receive it's signal to unlatch? It appears the Lincoln system has separate lock and open mechanisms but the language for the MME makes it appear like one module is double acting and it unlocks as well as opens the doors. How does that module know it's okay to open the door if the 12v battery is flat?

Is there enough energy stored in the door latch module to operate the B-pillar controls? If so, then must one use the keypad to unlock and the touch button to open?

(I am assuming the RKE or PAAK is useless with a dead 12v battery......) If that isn't the case then that is truly a remarkable engineering feat.
 

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if you know your car is going to sit for a while, how about you keep 80% in battery and remote start car for a short bit to keep it from completely killing 12v.

not sure why this is such a big issue, the past 20 + years I have had to jump start my car 0 times. I guess I should consider myself lucky, because it seems like some people have to jump start daily with all this concern....
 
 




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