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Comment by ajross | Hacker News Reader

The chemistry isn't a mystery. But certainly sealing a battery so it doesn't short when submerged in seawater isn't rocket surgery either. It's an engineering goof, and a pretty severe one. Figuring out how it happened is worth investigation, and given the context some of that is going to appear in the mainstream media.

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There is no way you're going to waterproof an electric car to the extent it can survive total immersion in seawater without doubling the cost. Immersing an electric car in seawater will kill it. Immersing a gasoline burning car in seawater will kill it. Immersing a gasoline burning boat will probably destroy the engine too.

Dropping a car in the ocean is far, far outside of the design envelope. It is simply not reasonable to expect the manufacturer to add cost to endure that unlikely of an event.

The rather famous 'Top Gear tries to kill a Toyota Hilux'.

https://www.youtube.com/watch?feature=player_detailpage&...

The part when the Hilux goes in the English Channel (which is salt water).

A diesel, with a far simpler ignition system. (well, old gas cars or dirtbikes with carbs are kind of the same way, but lack of spark plugs makes diesels even better with water)

An ordinary car battery (you know, with the exposed terminals on top) will short if you submerge it in salt water. It's not a problem specific to hybrid cars in any way, and it's kind of weird that the article tries to paint it as such.

A lead acid battery won't start a fire if you drop it in the ocean...

How do you know it didn't short outside the battery at a relay or junction point?

I know nothing, obviously, as it's still a "mystery". I do know, however, that putting a FET switch and a current sensor inside the seal is hardly rocket surgery...

If it was so easy to regulate extremely high voltages and current during extreme shorting, expensive line transformers wouldn't explode either during hurricanes.

A FET that handles that much power requires substantial heat sinking. You could make a hole in the seal for the sink, so the switch is inside and the heatsink is outside, but then you have to worry about how this will affect the integrity of the seal. It has to handle high temperature and pressure.

>>But certainly sealing a battery so it doesn't short when submerged in seawater isn't rocket surgery either. It's an engineering goof, and a pretty severe one.

No it is not. Look, it's not as if "being submerged in water" is a common condition for these cars. They are commuter cars, not off-road vehicles. I'm sure the manufacturer's engineering team could come up with an automatic sealing mechanism, but that would come with trade-offs from both price and complexity perspective. At the end of the day it just is not worth it.

Why is it a goof not to design the car to survive complete salt water immersion? Combined with protecting all the electronics and interior, I imagine that would add a large price to every single car for a situation everyone knows totals the car anyway. I don't think I'd pay anything extra for that feature, at least.

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