12v battery is the weakest link to many

[Shayne]

Door locks are controlled by the BCM. It can’t run off a capacitor.

Which is a problem because a 12V power supply has not yet been invented My GPU boots off the CMOS battery ? Appears a little 12V battery is used to boot and run the system when sitting. Not being able to refresh the app helped with sitting but as far as booting and installing OTA the power supply seems to not be used and both drain the 12v ?‍

The 12V is a weak link in this design for sure. My GPU can be updated when running off a power supply the only one that can not totally is a UEFI update.

Why does the BCM boot and update off the 12V?

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[E90alex]

Which is a problem because a 12V power supply has not yet been invented My GPU boots off the CMOS battery ? Appears a little 12V battery is used to boot and run the system when sitting. Not being able to refresh the app helped with sitting but as far as booting and installing OTA the power supply seems to not be used and both drain the 12v ?‍

The 12V is a weak link in this design for sure. My GPU can be updated when running off a power supply the only one that can not totally is a UEFI update.

Why does the BCM boot and update off the 12V?

You mean your PC? Your PC doesn’t boot off the CMOS battery, the CMOS battery is only used to maintain power to some volatile memory chips to store certain settings.

As for the car, everything on the car runs off of the 12V system, including the HV battery. The HV battery is only connected to the car when it’s needed, otherwise it’s electrically disconnected for safety. If the 12V battery is too weak, it can’t flip the switch to connect the HV battery into the system. This is not only a Ford issue, but every EV is designed this way.

 

[E90alex]

Imagine one is dying of dehydration by a big clear lake but he can’t even lick a single drop of water.

The problem is your body (LV batt) is too weak to bring you to the lake (connect the HV batt).

 

[Flyer_313]

Kinda?

But telling people they’re worrying about the wrong battery is only partially true.

Sure, your 12v is way more likely to fail than the HVB. But if it does, it’s a super cheap and easy fix in comparison.


It’s like saying you’re way more likely to be bitten by an ant than a shark (true), but which one will you worry more about at the beach?

I’ve survived many an ant bite.

if you are very worried about the 12v battery, for a few bucks you can buy a volt meter that plugs into the 12v outlet. You can easily see the state of charge.

 

[Snakebitten]

if you are very worried about the 12v battery, for a few bucks you can buy a volt meter that plugs into the 12v outlet. You can easily see the state of charge.

Is that 12V outlet active at all times?
It'd be cool if it is AND you can see the value through a window without disturbing/awakening the car.

 

[Flyer_313]

Is that 12V outlet active at all times?
It'd be cool if it is AND you can see the value through a window without disturbing/awakening the car.

I use the outlet in the rear of the car. You do have to turn the car on (only the accessories, don’t put your foot on the break petal). You get a reading of your battery state of charge.

 

[Shayne]

You mean your PC? Your PC doesn’t boot off the CMOS battery, the CMOS battery is only used to maintain power to some volatile memory chips to store certain settings.

As for the car, everything on the car runs off of the 12V system, including the HV battery. The HV battery is only connected to the car when it’s needed, otherwise it’s electrically disconnected for safety. If the 12V battery is too weak, it can’t flip the switch to connect the HV battery into the system. This is not only a Ford issue, but every EV is designed this way.

Exactly but it has a power supply which charges the 12V. Why is it is sucking 12V's dead. It does not have the logic of a computer but it is trying to be one. Why is it all running off the 12V battery and not the power supply with some volatile memory retained by a 12V was my point. Whole logic does not work the 12V should close the contacts and then be done. Not boot the whole system. Booting the GPU and hard drives off the cmos battery was just an analogy. The contacts should close more often and obviously for updates. Time will fix it but maybe not on this model/manuf.

Would be nice to have non-combustible batteries and barely use the contacts (disconnect). If you can boot and update a PC off a power supply you can do it with this car. If it is government regulations that need changing that should happen. The 12V should be under panels and we never need to worry about it

 

[E90alex]

Besides the safety aspect, the HV battery needs to be disconnected to allow the BMS to get accurate RCV measurements to recalibrate and to ensure
stray parasitic drains don’t kill the HV battery.

The fact is lead acid batteries just simply can fail without warning. There is no real accurate way to measure 12V battery health on the fly except measuring voltage. The voltage can read fine but if there is a weak or damaged cell it won’t be able to support much load/amperage. This has happened throughout all history of ICE cars. It’s not just an EV problem.

The problem is just exacerbated in EVs because the 12V is teeny tiny and there’s no early warning signs of a weakened battery like a slow/weak cranking starter. Combined with the fact that cars like the Mach-E have no easy way to open the door when the 12V is out.

You don’t see quite the same level of freak out about the 12V on Lightning forums for example because they can easily open the door and frunk even if it’s dead. They’re mostly concerned about charging the 12V to ensure getting software updates.

It’s an imperfect system for sure but there’s no great solution at the moment. Tesla for example has moved to a lithium ion LV battery which seems to be more reliable but if course that will increase cost, not just for the factory but make eventual replacement by the end user difficult and expensive.

 

[Shayne]

Besides the safety aspect, the HV battery needs to be disconnected to allow the BMS to get accurate RCV measurements to recalibrate and to ensure
stray parasitic drains don’t kill the HV battery.

The fact is lead acid batteries just simply can fail without warning. There is no real accurate way to measure 12V battery health on the fly except measuring voltage. The voltage can read fine but if there is a weak or damaged cell it won’t be able to support much load/amperage. This has happened throughout all history of ICE cars. It’s not just an EV problem.

The problem is just exacerbated in EVs because the 12V is teeny tiny and there’s no early warning signs of a weakened battery like a slow/weak cranking starter. Combined with the fact that cars like the Mach-E have no easy way to open the door when the 12V is out.

You don’t see quite the same level of freak out about the 12V on Lightning forums for example because they can easily open the door and frunk even if it’s dead. They’re mostly concerned about charging the 12V to ensure getting software updates.

It’s an imperfect system for sure but there’s no great solution at the moment. Tesla for example has moved to a lithium ion LV battery which seems to be more reliable but if course that will increase cost, not just for the factory but make eventual replacement by the end user difficult and expensive.

Question is why is it doing updates completely off the 12V so the lighting forums are concerned about it? That is one of the prime killers/abusers from what I have seen so far.

I think it is no different than the logic of booting and updating a PC which does not happen off the 12V CMOS battery. It runs off a 12V power supply. This car does not and counts on the 12V way too much. If it can get its 12V's from a 12V battery it should be able to get it from a 12V power supply ran off the big battery. It does but not to boot or update.

What about something like the KONNWEI KW208 tester?

 

[E90alex]

Question is why is it doing updates completely off the 12V so the lighting forums are concerned about it? That is one of the prime killers/abusers from what I have seen so far.

I think it is no different than the logic of booting and updating a PC which does not happen off the 12V CMOS battery. It runs off a 12V power supply. This car does not and counts on the 12V way too much. If it can get its 12V's from a 12V battery it should be able to get it from a 12V power supply ran off the big battery. It does but not to boot or update.

What about something like the KONNWEI KW208 tester?

The same reason your phone or tablet needs a minimum battery level before it will update even if it’s plugged in. It may not need to rely on the 12V for the entire update process but it may need to update the computer that controls the HV battery connection. It wants to be sure the 12V won’t die in the middle of an update and brick the car.

 

[Shayne]

The same reason your phone or tablet needs a minimum battery level before it will update even if it’s plugged in. It may not need to rely on the 12V for the entire update process but it may need to update the computer that controls the HV battery connection. It wants to be sure the 12V won’t die in the middle of an update and brick the car.

I disagree as that is the main phone battery not a tiny second one. If the MME HVB had to be over 50% I would agree but it is some tiny 12V that is the weak link. It would be great if it did updating off the big battery like the phone. The phone updates with the OS running not shutting it down, locking it and running away.

Since this car is trying to become a computer it is good to look at how PC's run. They run on 120V ac feed thru a 12V power supply to a MB and GPU. I can update all while running off the power supply. I am sure that can be extended to a 12V power supply that is feed with 365V or 500V DC. In fact our car is charging the 12V right now off the HVB.

Why does it need to boot every module and update off a 12V? This is a basic logic fault if you ask me. I would wait a few more seconds for the power supply to fire up to boot everything in the car. I do not think any modules would know if they are just killing the 12V or running off the power supply; should not matter where the juice comes from. Only thing that the 12V should be doing is closing the contacts to run off the big battery at lot more often and sooner.

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