What circumstances would cause an electrical fire in a parked MME?

[rhfritz]

Can anyone explain why this would've happened and are we susceptible to this?

www.cnn.com/2024/09/30/us/video/tesla-fire-florida-hurricane-helene-digvid

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[JoanS]

Can anyone explain why this would've happened and are we susceptible to this?

www.cnn.com/2024/09/30/us/video/tesla-fire-florida-hurricane-helene-digvid

Incursion of sea water into the battery.

 

[Mach-Lee]

Can anyone explain why this would've happened and are we susceptible to this?

www.cnn.com/2024/09/30/us/video/tesla-fire-florida-hurricane-helene-digvid

Tesla’s have drain holes in the bottom of the pack, when submerged eventually the water seeps in and the holes open up even more. Then the water shorts out the battery pack. Ford packs do not have these drain holes.

Do not park an EV where it may become submerged in water. They can only handle a brief stint underwater.

 

[njb]

It's not just the water. Not that the water is fine, but the salt water is extra conductive.

 

[Tampamike]

It's not just the water. Not that the water is fine, but the salt water is extra conductive.

Actually, fresh water is more conductive. Don’t ever swim near a fresh water marina - stay current can kill ya.

 

[corradoborg]

Actually, fresh water is more conductive. Don’t ever swim near a fresh water marina - stay current can kill ya.

Sorry, @njb got it right. Saltwater is the more conductive fluid compared to freshwater. H2O itself isn't conductive at all. It's the dissolved impurities in water that determine its conductivity. Na and Cl ions conduct VERY well.

 

[HuntingPudel]

Actually, fresh water is more conductive. Don’t ever swim near a fresh water marina - stay current can kill ya.

That’s the exact opposite of what my middle school chemistry teacher said. We even did an experiment using pure water vs salt water and found that the pure water had infinite resistance. ?‍?

 

[Mach-Lee]

All the floodwater your car will end up in is conductive can short out the battery (because of dissolved ions), whether it's salt water or lake/river water. I want to emphasize that it's not just saltwater you have to worry about. But saltwater is more conductive/worse.

Pure water isn't very conductive, but it will still conduct a tiny amount of electricity. 18.2 megohms per cm to be exact. That's not enough to light up the light bulb in the chemistry demo, but if you push the voltage high enough and get the electrodes close enough it will.

 

[Tampamike]

That’s the exact opposite of what my middle school chemistry teacher said. We even did an experiment using pure water vs salt water and found that the pure water had infinite resistance. ?‍?

I stand corrected. Yes, saltwater conducts electricity better than fresh. However, I was half right. It is more dangerous to swim near a fresh water marina because any stray current will more easily go through you than the fresh water. In salt water the stray current goes through the water to ground. Back to our regular programming …

 

[ChasingCoral]

That’s the exact opposite of what my middle school chemistry teacher said. We even did an experiment using pure water vs salt water and found that the pure water had infinite resistance. ?‍?

Freshwater isn't pure water. Even the purest freshwater body has enough ions to be highly conductive.

 

[rhfritz]

Having lived in places where torrential downpours would cause freeway flooding, I recall driving my ICE through water that was nearly up to the bottom of the doors, mid-way or higher up the wheels. As I understood it, the concern was not taking your foot off the gas or you'd possibly get water in the muffler, stalling the car. Some folks additionally talked about water in the transmission. But in my ICE, it was survivable, and I had that car many years after. Would you drive your Mach-e in water that deep?

 

[Gimme_my_MME]

Having lived in places where torrential downpours would cause freeway flooding, I recall driving my ICE through water that was nearly up to the bottom of the doors, mid-way or higher up the wheels. As I understood it, the concern was not taking your foot off the gas or you'd possibly get water in the muffler, stalling the car. Some folks additionally talked about water in the transmission. But in my ICE, it was survivable, and I had that car many years after. Would you drive your Mach-e in water that deep?

Honestly you should never drive any car in flood water that deep as you don't know what debris or obstacles are present. You may hit a pothole that you couldn't see and now you are suddenly deeper than you thought. And you should never underestimate the power of moving water!

 

[RickMachE]

Having lived in places where torrential downpours would cause freeway flooding, I recall driving my ICE through water that was nearly up to the bottom of the doors, mid-way or higher up the wheels. As I understood it, the concern was not taking your foot off the gas or you'd possibly get water in the muffler, stalling the car. Some folks additionally talked about water in the transmission. But in my ICE, it was survivable, and I had that car many years after. Would you drive your Mach-e in water that deep?

I would read the manual on both cars, because it gives me that exact answer.

Unless it was a matter of life and death, no, I would not drive ANY vehicle in water that deep. No one should.

 

[rhfritz]

I would read the manual on both cars, because it gives me that exact answer.

Unless it was a matter of life and death, no, I would not drive ANY vehicle in water that deep. No one should.

I agree. The Houston freeways routinely flash flood. The bigger risk of driving was to lose sight of the road and end up in the bayou. But the point is that your car was going to end up in brackish water on otherwise flat, slow-draining land. But it's definitely a consideration with an EV whose entire undercarriage is battery. My Prius battery is below the trunk deck but above the gas tank.

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