Car Bricked While Driving. Any Thoughts on This

[kltye]

these type of products are designed to provide lots of amps, but just for a few seconds, to start an ICE vehicle... or very low amps for a *longer* time to charge a phone or run a 12v LED flashlight. Suitable for popping the Frunk, and perhaps enough juice to unlock your doors....

But ***NOT*** enough Energy to run an EV computer control system and computer for more than a few minutes if the HVB -> LVB charge system has failed and that is why the LVB is dead.

I would humbly suggest that carrying a 'jump battery' anywhere in a BEV is a waste of money and space. If you are worried about the dead 12v issues, you will be much better off to prepare for a significant energy transfer from a running vehicle with regular old jumper cables connected to your 12v 'connection points' for a good 20 minutes to transfer a meaningful amount of energy from the running vehicle to your (presumably dead) 12v battery... enough to get you to the dealership to figure out why your 12v is not getting charged.

5 minutes with a 2" hole saw will provide easy access to connection points so you don't have to remove plastic covers to get, or give, a jump. $2 plastic plugs available at any hardware store will make it look almost OEM.

https://www.macheforum.com/site/threads/how-to-add-access-ports-for-lvb-connection-points.4107/

LVB issues are more than just loose bolts - software issues might prevent the DC-DC converter to charge the LVB until the car is fully "on", for example. I had to jump my car with one of those packs after I flashed it with FDRS because the LVB died in the process. In my old C-Max Energi, one day I walked up to it and it was completely dead for no apparent reason. Managed to get in with a physical key and jumped it. Never had a problem like that again. You don't have to get a battery with a bazillion amps to start some computers and pumps, but it's always good to have one around to double-check what the issues are when you're out "in the field".

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[generaltso]

I had to jump my car with one of those packs after I flashed it with FDRS because the LVB died in the process.

Did you ignore the warning in FDRS that says to make sure you have the LVB hooked up to a power supply?

 

[kltye]

Did you ignore the warning in FDRS that says to make sure you have the LVB hooked up to a power supply?

Sure did! Actually, the power supply wasn't powerful enough, and I was doing an IPMA flash. Not blaming anyone or anything, and I wasn't willing to spend a ton of money on a power supply I'd use a few times a year, and I already had the backup battery from my old ICE vehicle.

 

[PCS2021]

Driving to work this morning going around a corner doing about 55 mph and my car died. No power, no lights, nothing. Steering and braking was almost impossible but I managed to get it to the shoulder. There was zero warning, just died.

Now I’m sitting here waiting for a tow truck knowing I can’t put it in neutral.

I’ve had the car for 4 months and have 8000 miles but have never had a single issue.



Edit - Problem resolved.

On advice from another member, I'm editing this thread.

Please read through for all of the details but here's the short version of the fix.

Found a loose connection in the 12 volt distribution box. Had to tighten the red wire on the right,

How and where do you find this electrical junction? Better now to check the tightness.

 

[dtbaker61]

How and where do you find this electrical junction? Better now to check the tightness.

- remove rear and side 'frunk' beauty covers
- remove frunk tub
- (optional, but suggested) open HVB relay connector to prevent dc-dc from energizing the post
- (optional, but suggested) remove battery 12v- connection to prevent accidental ground
- detach and move aside fuse box... low and behold, there is the 12v+ connection post/wire/nut.

... allow at least a good solid 1/2 hr labor to get to this nut, and probably another 1/2 hr to replace it all.

 

[JcMarin]

Driving to work this morning going around a corner doing about 55 mph and my car died. No power, no lights, nothing. Steering and braking was almost impossible but I managed to get it to the shoulder. There was zero warning, just died.

So, I understand the need for the LVB as every single ECU/Chip/System on the car is fed from the 12v, and I also understand that this can not be fed from the HVB and the need to separate both, but there has to be a better way or at least some redundancy if its that critical.

If some ICE have 2 batteries (mainly for start-stop) couldn't these EV have something similar? at least if the "start" battery dies the "System" battery would still keep some critical systems alive so you don't lose all control of the car while driving 55mph in a curve!

Maybe a separate Lithium battery for Critical systems?

 

[Jimmy2]

- remove rear and side 'frunk' beauty covers
- remove frunk tub
- (optional, but suggested) open HVB relay connector to prevent dc-dc from energizing the post
- (optional, but suggested) remove battery 12v- connection to prevent accidental ground
- detach and move aside fuse box... low and behold, there is the 12v+ connection post/wire/nut.

... allow at least a good solid 1/2 hr labor to get to this nut, and probably another 1/2 hr to replace it all.

Excellent step by step. Question: What tools are the best to carry around to make these steps as easy as possible?

 

[louibluey]

I would think, without looking it up, that the torque would be less than 10 fp. I would just but a 1/4 ratchet from Amazon to do the job.

I got the torque ratchet wrench and was just working with it using a 1/4" bolt in a vise. I was tightening two 7/16" nuts against each other with and without an electrical lug.

Using a 6" crescent wrench, I just hand tighten until it stops with some small force to tighten the nut. It is really difficult to explain that in words. I guess we just develop that muscle memory for different metals, types, and sizes of bolts over decades of assembling things. Also, it is more difficult to break a 1/4" bolt with a 6" crescent wrench.

Using the 1/4" ratchet torque wrench, about 90 - 100 inch pounds seems okay to me. 110 inch pounds was okay, but might be pushing the very outside edge of deformation depending on the metals and thread pitch. Perhaps in most cases with a typical electrical lug, there is slight deformation of the softer metal of the lug first.

Interestingly, it is very easy to over torque (on purpose) and sheer the 1/4" bolt with the longer one foot handle of even the relatively small 1/4" torque wrench.

I tried tightening the outer nut on a lug with just the 6" crescent wrench alone several times. As best as I can tell, I end up at about the same place as with the torque wrench set to about 100 in lbs.

I guess the reason hand tightening works so well (at least with some experience) is that the nut just stops. The amount of the force needed to turn the nut further past the initial stopping point increases rapidly, so with some experience, you can just feel it (about proper torque) for a given length of tool arm. In some circumstances, for example, techs prefer the shorter crescent wrench for just that reason, it is more difficult to over torque the nut on the lug.

Anyway, I am glad to have a small 1/4" ratcheting torque wrench now, but I think the human indication of tightening small electrical connections is just about as good, at least outside of a factory assembly setting. That is probably why the Ford Work Shop Manual just says in trouble shooting, to be sure the connections are tight or something to that effect (with no published torque values).

For those with less experience, a good final check is to gently try to rotate the electrical lug. Generally, if you can cause the nut to turn by pushing sideways on the lug (do not deform or bend the lug!), the nut is too loose.

 

[Jon]

Maybe a separate Lithium battery for Critical systems?

I think this is a great idea. No reason not to have some redundancy to prevent a single point failure.

 

[dtbaker61]

So, I understand the need for the LVB as every single ECU/Chip/System on the car is fed from the 12v, and I also understand that this can not be fed from the HVB and the need to separate both, but there has to be a better way or at least some redundancy if its that critical.

If some ICE have 2 batteries (mainly for start-stop) couldn't these EV have something similar? at least if the "start" battery dies the "System" battery would still keep some critical systems alive so you don't lose all control of the car while driving 55mph in a curve!

Maybe a separate Lithium battery for Critical systems?

not a great idea to use a lithium battery in places that will likely be <0C

It would be smarter to have a better, very visible indicator on instrument panel if LVB ever drops below 11.9v... something more informative than 'stop vehicle now', indicating that LVB is not charging properly, and service is required immediately.

 

[louibluey]

not a great idea to use a lithium battery in places that will likely be <0C

It would be smarter to have a better, very visible indicator on instrument panel if LVB ever drops below 11.9v... something more informative than 'stop vehicle now', indicating that LVB is not charging properly, and service is required immediately.

Interesting, maybe that is what Ford was trying to do with those various 12V warnings that many of us got during the winter. But, they just don't have it right yet.

 

[louibluey]

So, I understand the need for the LVB as every single ECU/Chip/System on the car is fed from the 12v, and I also understand that this can not be fed from the HVB and the need to separate both, but there has to be a better way or at least some redundancy if its that critical.

If some ICE have 2 batteries (mainly for start-stop) couldn't these EV have something similar? at least if the "start" battery dies the "System" battery would still keep some critical systems alive so you don't lose all control of the car while driving 55mph in a curve!

Maybe a separate Lithium battery for Critical systems?

If you are driving, the DC/DC converter is the redundancy. If the DC/DC converter is not already running, it will come on at lower 12V bus voltages. So in a sense, MME can "feed" the 12V bus from the HVB.

I suspect this failure is very unusual, if not a one-off. Such failures are prevented by proper electromechanical design, and good assembly techniques with QA/QC backing up critical assembly points.

It may be in that electrical systems, there are places where one single path just makes sense, such as to be able to fuse open all 12V high current in some failure conditions.

 

[dtbaker61]

Interesting, maybe that is what Ford was trying to do with those various 12V warnings that many of us got during the winter. But, they just don't have it right yet.

a $10 voltmeter left in any one of the 'power outlets' is cheap insurance that might make people feel better ?! But, you have to actually look at it once in a while as well as remember that it should NEVER show less than 12.0, and not less than 13.0 when the MME is 'on'.

https://www.amazon.com/KEWIG-Charge...ef=pd_day0fbt_img_sccl_1/137-3075184-8366349?

 

[Lockesmith]

- remove rear and side 'frunk' beauty covers
- remove frunk tub
- (optional, but suggested) open HVB relay connector to prevent dc-dc from energizing the post
- (optional, but suggested) remove battery 12v- connection to prevent accidental ground
- detach and move aside fuse box... low and behold, there is the 12v+ connection post/wire/nut.

... allow at least a good solid 1/2 hr labor to get to this nut, and probably another 1/2 hr to replace it all.

Thank you for highlighting the optional steps. I am terrible with electricity so just want to double-check my understanding. If I open the HVB relay and remove 12v- battery connection, will nothing happen if I accidentally short myself/wrench to the frame while tightening this?

 

[dtbaker61]

Thank you for highlighting the optional steps. I am terrible with electricity so just want to double-check my understanding. If I open the HVB relay and remove 12v- battery connection, will nothing happen if I accidentally short myself/wrench to the frame while tightening this?

Right

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