Survey: High Voltage Battery Junction Box issues?

[mkhuffman]

great survey.... going to get some good data there I think.

In the meantime, I have a new theory on root cause of contactor (HVBJB) failure.... I'm thinking is could start with low 12v system voltage causing contactor relays to 'flutter' and not close solidly, arc, and weld shut.

I'm thinking that if the 12v battery happens to be run down, lets say close to 12.0 v, you hop in the car, start, turn on 12v loads like heat/air conditioning, then drive off right away... flipping on the 12v loads pulls the 12v system voltage down before the dc-dc has time time to 'charge the 12v', and the contactor relay can't hold good contact while you are accellerating getting rolling, and weld themselves together; which the car notices probably at your next stop when the contactors fail to open. This might also happen at a DCFC station I suppose if the 12v system is low, you plug in the DCFC and have big current flowing and the 12v system voltage sags a bit and can't hold the contactors....

This may explain why the vehicles don't have, or solve 12v charging issues, avoid the HVBJB problem.

@SpaceEVDriver - I know we have a lot of responses to the survey already, but it would be good to know if anyone has had LVB errors or 12V low voltage warnings. I only got them when I had my ODBII reader connected with the car not charging and off. Those errors were caused by me, but what about LVB errors not caused by the owner? Could there be a correlation?

It is scary to think that by testing and stressing my LVB, I may have increased the risk of getting a HVBJB failure. Maybe.

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[dtbaker61]

@SpaceEVDriver - I know we have a lot of responses to the survey already, but it would be good to know if anyone has had LVB errors or 12V low voltage warnings. I only got them when I had my ODBII reader connected with the car not charging and off. Those errors were caused by me, but what about LVB errors not caused by the owner? Could there be a correlation?

It is scary to think that by testing and stressing my LVB, I may have increased the risk of getting a HVBJB failure. Maybe.

a good question to add would be 'have you ever gotten a low LVB warning, or noticed 12v system below 12.0v ?'

 

[cvk71]

I had the HVBJB occur around 1000 miles ago but I have not had the LVB warning at any time.

 

[Shayne]

Please fill out the survey in the first post. It's fully anonymous.

Not sure how to do that

Total voters 72 Poll closed Sunday at 9:01 PM.

 

[BadgerGreg]

Can you pipe in if you did not make the poll?
3 times ~600 km and last at ~9000 Km
Production Date: "2020-11-26",
received February 2, 2021
Hoping 3rd time is the charm?

Ouch...three-timer?!?! Glad you're making use of the membership card, though...

 

[mkhuffman]

Not sure how to do that

Total voters 72 Poll closed Sunday at 9:01 PM.

Dude.

https://forms.gle/w5VpcyMLv8LecH3G7

 

[AllenXS]

All fixed, working well.
They found a loose C1815C was not fully seated as well.

 

[LUV_RED]

I don't have my MME yet so can't take the poll, but was wondering if any of the cars that have had failures had chip holds on them after production to possibly drain the LVB.

 

[MightyMike]

So among other threads it seems that there is a theory forming that a low 12V battery might induce a condition in which the HVBJB might fail.

is there a way to evaluate the 12V battery to determine whether it is close to failing? Or do these batteries tend to fail suddenly without warning.

 

[dtbaker61]

So among other threads it seems that there is a theory forming that a low 12V battery might induce a condition in which the HVBJB might fail.

is there a way to evaluate the 12V battery to determine whether it is close to failing? Or do these batteries tend to fail suddenly without warning.

agm batteries do not generally fail suddenly....

easiest way to monitor is a $10 voltmeter left in an aux power port like the one in the center armrest. It should *never* read below 12.0 v, and should read 14.5v or so when the car is 'on'.

 

[TonyaE]

agm batteries do not generally fail suddenly....

easiest way to monitor is a $10 voltmeter left in an aux power port like the one in the center armrest. It should *never* read below 12.0 v, and should read 14.5v or so when the car is 'on'.

I like this idea.

 

[dtbaker61]

I like this idea.

https://www.amazon.com/Palumma-Char...0773BYS6P/ref=rvi_sccl_6/137-3075184-8366349?

or similar units are easy to find on Amazon....

 

[TonyaE]

https://www.amazon.com/Palumma-Char...0773BYS6P/ref=rvi_sccl_6/137-3075184-8366349?

or similar units are easy to find on Amazon....

Added to wish list. Thanks?

 

[Logal727]

All fixed, working well.
They found a loose C1815C was not fully seated as well.

Wait really?

 

[AllenXS]

Wait really?

that's on the service report.
I was going to ask if it was standing or had its belt on but thought better of it.

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