Just saw Rivian R1S burning on 101 Brokaw

[godfodder0901]

Ok so, am I missing something here?

I feel like towing improperly shouldn't cause A FIRE.

I can see it damaging the motor/inverter, but how does that cause it to catch fire??? That seems like a major design flaw if that's the case. These things are gonna get improperly towed all the time

I feel like a much more likely cause would be the fact that the battery was damaged in whatever wreck it was in before getting towed. (Or possibly the other wrecked vehicle being towed caught fire and it spread).

Maybe I'm off but improper towing causing it to go up in flames seems insane

A motor in reverse rotation, like these wheels would be, is just a generator. The power has to be dissipated in some way, and the most likely form is heat. This outcome doesn't surprise me in the slightest.

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[KBabione]

I may be wrong here, but I think the parking brake is only on the rear wheels. If the R1S had been in an accident or the battery was otherwise dead, the operator couldn't put it in "Tow Mode" which means that the motors were spinning and generating current that had no place to go while he was towing it - that would have generated a lot of heat and we see the result. Flame away if you have other opinions

 

[godfodder0901]

I may be wrong here, but I think the parking brake is only on the rear wheels. If the R1S had been in an accident or the battery was otherwise dead, the operator couldn't put it in "Tow Mode" which means that the motors were spinning and generating current that had no place to go while he was towing it - that would have generated a lot of heat and we see the result. Flame away if you have other opinions

Tow Mode isn't a thing. The Tow Operators Guide recommends Shipping Mode to preserve battery life and disable the alarm, but there is no mode that will disconnect the motors from the wheels while towing.

 

[mpshizzle]

A motor in reverse rotation, like these wheels would be, is just a generator. The power has to be dissipated in some way, and the most likely form is heat. This outcome doesn't surprise me in the slightest.

I may be wrong here, but I think the parking brake is only on the rear wheels. If the R1S had been in an accident or the battery was otherwise dead, the operator couldn't put it in "Tow Mode" which means that the motors were spinning and generating current that had no place to go while he was towing it - that would have generated a lot of heat and we see the result. Flame away if you have other opinions

My train of thought is that it would take A LOT of heat to cause the battery to combust spontaneously. Based on some quick googling, sounds like the point where a lithium ion battery combusts from heat is around 300 F.

In my mind a motor just sitting there spinning would, indeed generate a lot of heat - enough to burn up itself and the inverter. But I have a hard time believing that alone would heat up to 300 degrees, let alone getting the battery to 300 degrees. Remember, if the vehicle is not in "go" mode, there is no electrical connection between the motor and the battery.

I'm no engineer, but that doesn't seem right to me. Seems like it's much more plausible that some of the cells got shorted/punctured than it would be for the motor to get to 300 degrees.

 

[bigsky]

Imagine, just try to wrap your head around the idea of reporting, sensationalizing each of the gazillion more fires on ICE vehicles, and not because there are more of them.
Sensationalism at its worst here. A nothingburger in terms on news worthiness. Ho-hum.

 

[godfodder0901]

My train of thought is that it would take A LOT of heat to cause the battery to combust spontaneously. Based on some quick googling, sounds like the point where a lithium ion battery combusts from heat is around 300 F.

In my mind a motor just sitting there spinning would, indeed generate a lot of heat - enough to burn up itself and the inverter. But I have a hard time believing that alone would heat up to 300 degrees, let alone getting the battery to 300 degrees. Remember, if the vehicle is not in "go" mode, there is no electrical connection between the motor and the battery.

I'm no engineer, but that doesn't seem right to me.

The fire wasn't necessarily in the battery. The motors get to nearly 300 by themselves when warming the battery or preparing for DCFC, so it's not inconceivable that the inverter could be driven to well above that in the towing scenario. That much heat could easily cause any number of things in the vicinity to combust.

 

[KBabione]

Tow Mode isn't a thing. The Tow Operators Guide recommends Shipping Mode to preserve battery life and disable the alarm, but there is no mode that will disconnect the motors from the wheels while towing.

Yes - I got confused with the instructions for releasing the parking brake. Look what I found:

It even warns you that it will cause excessive heat and may cause a fire!

 

[bigsky]

Imagine, just try to wrap your head around the idea of reporting, sensationalizing each of the gazillion more fires on ICE vehicles, and not because there are more of them.
Sensationalism at its worst here. A nothingburger in terms on news worthiness. Ho-hum.

 

[mpshizzle]

he motors get to nearly 300 by themselves when warming the battery or preparing for DCFC

....WUT? I've never seen mine get above 115 or so!

 

[mpshizzle]

Says right there - Fire hazard. That's crazy. I stand corrected

Still though... 300 F when pre-conditioning doesn't sound right at all lol

 

[godfodder0901]

....WUT? I've never seen mine get above 115 or so!

G1 QUAD Overheating Motors | Rivian Forum - R1T R1S R2 R3 News, Specs, Models, RIVN Stock -- Rivianforums.com

 

[HaveBlue]

Rivian has permanent magnet motors. The rear can be decoupled with the clutches but in tow mode it will brake/park if you tow very quick. Not good if you ignore that. The front is also permanent magnet. Spin those by towing and the power is going to over heat everything without management.

Basically it's like towing an ice car if it is in park or in gear. Not going to be pretty.

Teslas have one induction motor that decouples if the coils aren't powered externally. It can free wheel safely all day.

 

[godfodder0901]

Says right there - Fire hazard. That's crazy. I stand corrected

Still though... 300 F when pre-conditioning doesn't sound right at all lol

The temp readout doesn't even turn orange until ~284...

 

[mpshizzle]

The temp readout doesn't even turn orange until ~284...

I knew the G1 quads ran hot.. but hot DAMN (literally) ?

 

[godfodder0901]

I knew the G1 quads ran hot.. but hot DAMN (literally) ?

Gen 2 will be a bit better because they have better cooling, but these temps aren't that extreme.

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