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2017 Chevy Bolt EV Premium - Metallic Grey
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Discussion Starter #1

What are the odds they were using some uncertified charger?
What are the odds they had rats eating away their harnesses to the point of short circuiting?

THE HUMANITY!!!!

:)
 

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No Bolt expert here ... don't even own one (yet), but white smoke reminds me of burning coolant out the exhaust in an ICE vehicle. Makes me wonder if the battery coolant was burning somehow?
 

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2019 Chevy Bolt LT, Cajun Red
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Link please?

 

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What are the odds they were using some uncertified charger?
What are the odds they had rats eating away their harnesses to the point of short circuiting?

THE HUMANITY!!!!

:)
Some sort of uncertified charger? Unfortunately this is not a plausible failure mode. The only reason this would ever cause a fire would be a bad connection in the actual J1772 plug itself, and it would happen at the charging port, having nothing to do with the charger itself.

It's probably the fuse under the back seat, as everybody's been saying for ages. And it ought to be investigated, so these problems are identified, and standards of quality are set in the industry.

The government won't kill electric cars over this, whatever it is. But if they make a rule of "no crappy fuse holders" we'll all be better off.
 

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Some sort of uncertified charger? Unfortunately this is not a plausible failure mode. The only reason this would ever cause a fire would be a bad connection in the actual J1772 plug itself, and it would happen at the charging port, having nothing to do with the charger itself.

It's probably the fuse under the back seat, as everybody's been saying for ages. And it ought to be investigated, so these problems are identified, and standards of quality are set in the industry.

The government won't kill electric cars over this, whatever it is. But if they make a rule of "no crappy fuse holders" we'll all be better off.
The reports in the articles has been that the fire starts at the rear seat position, or 'back' of the vehicle as it's described. Things break, design snafu's get weeded out over time. Sheet happens.
 

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It's probably the fuse under the back seat, as everybody's been saying for ages. And it ought to be investigated, so these problems are identified, and standards of quality are set in the industry.
That was my first thought in the other thread. However, a couple of those incidents seemed to have happened while the Bolt was parked and not charging. I can't imagine a scenario where that fuse would have any significant current running through it while the car is parked: certainly not the level of current demanded while driving. The fuse sits on top of the battery and being at the upper section of the battery, is probably just a weak spot for anything that fouls inside the battery. Seems more likely to me that if some cells went critical inside the battery, the heat may escape there first and the MSD is likely not the cause of the failure but rather just a weak point to release the energy. It's not like the fuse can "short out"... a fuse is already a "short".

Edit: in addition, for someone like me who did the recall himself (replaced the MSD with the updated part)... makes me wonder if mine went up in flames, they could blame me, saying I installed the fuse incorrectly. Hmm...

Mike
 

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That was my first thought in the other thread. However, a couple of those incidents seemed to have happened while the Bolt was parked and not charging. I can't imagine a scenario where that fuse would have any significant current running through it while the car is parked: certainly not the level of current demanded while driving. The fuse sits on top of the battery and being at the upper section of the battery, is probably just a weak spot for anything that fouls inside the battery. Seems more likely to me that if some cells went critical inside the battery, the heat may escape there first and the MSD is likely not the cause of the failure but rather just a weak point to release the energy. It's not like the fuse can "short out"... a fuse is already a "short".

Edit: in addition, for someone like me who did the recall himself (replaced the MSD with the updated part)... makes me wonder if mine went up in flames, they could blame me, saying I installed the fuse incorrectly. Hmm...

Mike
But a loose fuse or connections within can arc.
 

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But a loose fuse or connections within can arc.
That is certainly true. The reason I think that unlikely is if that were the case, wouldn't it arc when the car is being driven and consuming 100kW from time to time and not when it is parked and presumably not using much (if any) current? I suppose it's possible that the fuse could have started to catch at the end of a drive and not been noticed since it's under the seat but statistically they should catch while driving and we wouldn't have all three cases occur after the car is parked.

Mike
 

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I believe the fuse joins two halfs of the battery and always has voltage to it so it is always live". I may be wrong but pretty sure. 400 volts DC can make a pretty big spark. This all may have to do with the MSD recall but of course I am guessing. I would not be surprised if some GM engineers are about to be fired for not putting this main fuse in a thick metal box like fuses are suppose to be in. Isn't it out in the open when you lift the seat?
 

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Anything we say now is speculation, and I will add my bit here, I think it may be the BCM inside the battery, I can imagine it trying to balance a battery cell and for some reason getting stuck in the discharge cell mode, overheating and triggering the fire.
The fuse had to be recalled because it was degrading, over time the maximum current it can handle was being reduced until a point when it could not even manage the normal load of the car and just became an open circuit.
 

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The fuse can only connect one leg of the battery (my guess is the negative leg). But there's more in that MSD than just the fuse. There are also other contacts in there. If I had to guess, the other contacts are probably there to detect the voltage drop across the fuse to determine whether or not the fuse is "healthy". They also may be there to detect the amount of current passing through the fuse (to give you your kW reading). In any case, it's possible that the "other" circuitry in the MSD failed and burned and not the 500A fuse itself. Something to think about. Being under the rear seat, I suppose it's possible that gum wrappers or other seat-prone debris could get near the MSD. That thing is pretty sealed though so I don't see a scenario where bits of trash could get INSIDE the MSD.

Edit: I wonder if in the fire cases, people were sitting in the rear seat prior to the car being parked? The MSD is pretty well recessed below the seat but what if, in certain cases like a "weighty" person sitting in the middle, it could put stress on it. Then when they move/slide out to get out of the car, it is stressing something?

Mike
 

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The MSD is indeed in the middle of the pack, splitting it in two. However, it is not always live. When the car is turned off, there are two relays, one on the positive end terminal, and one on the negative end terminal of the battery. One would be sufficient to have an open circuit, and no current through the battery, but there are two for redundancy.

The MSD itself has no additional parts, other than blade contacts, and a fuse. I do not believe there is a way for this ceramic fuse to explode, or get hot enough to start a fire. The socket it fits into does have other sensor leads to monitor its health, and I suppose part of that system could fail and cause a fire.

1602777425497.png

My money is still on the Battery Mangling System. The BMS, by design and necessity, is always live.

1602777546863.png

I can verify, from watching the temperatures on Torque Pro, that it generates enough heat, when operating normally, to make module 6 warmer than any of the others, just by sitting on top of it.

12-29-18-1.jpg
 

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It is not stuff getting into the MSD, or the BCM, it is sparks getting out that concern me. This is why the electrical code requires all junction boxes, fuse panels and switches to be fully covered. Boxes in walls can not be recessed behind the front of the sheetrock. I have never looked at the MSD but have seen pictures.
 
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