Water Safety

Water Safety

What would happen to the passengers when a vehicle either partially or fully submerge in water? It is rare but I do see cars get stuck in deep water during flood season and there's a chance you might accidentally drive the car into a lake or off a bridge... With so much electricity, would I be electrocuted?

Vawlkus | 28 October, 2010

I believe that the crash sensors in a Roadster & Model S would be activated by the initial touch of water, and would disconnect the battery before the car is more than 1 inch submegred (those are guesses).

Timo | 28 October, 2010

OTOH, the battery uses liquid coolant, so that is protected, and wires are also insulated, so water is not dangerous until it reaches unprotected live connectors. If you could make those water-proof too then you could drive under water. Most submarines run on electricity.

I think the lowest failure point is the engine. That is air-cooled and low on chassis, so it probably also has exposed live connectors. Second is PEM (where ever that is in Model S).

In fact placing battery in floor makes protecting it and connectors in it from water quite big issue. Otherwise you could get stranded in shallow 20cm deep water puddle.

Fast swapping can affects this. In cold climate ice tends to form inside car in any structural gap, so if there is a possibility to battery to get ice forming near connectors and those are exposed it can be difficult for sensors to pick up. I hope that has been considered in designing.

Vawlkus | 29 October, 2010

I was under the impression that the underside of the car was one solid piece. Water'd not going to be getting into that, even if the battery is removable, I seriously doubt the fit is less than water tight.

In fact, the only place I can see water ingress is through the grate in the front. Provided the motor isn't on the very bottom of the car's frame, water would need to build up to the top of the wheel wells before it could come into contact with the motor.

If the Tesla crew are smart (and I believe they are ;) ), then they've got a drain in the motor compartment and a water deflector so that water is directed downward, and air is channeled upwards, so that the air will cool the motor, and the water will drain away.

Tim10 | 29 October, 2010

I believe the PEM, Motor and battery back are supposed to be liquid cooled which should mean they are water tight. Only possible concern would come from power cables/connection points and I suspect there will be an auto disconnect of the battery if an event like this occured.

Timo | 29 October, 2010

With ice it is a bit different issue than just being water proof. It would need to be air tight to prevent ice from forming. Any moisture in air freezes at cold climate, so if there is any kind of gap for it to build up it will build up. It might then reach the connectors. OTOH, that kind of ice is pretty poor conductor, it is basically distilled water and pure distilled water is nearly insulator more than conductor (add in salt and other impurities and it starts to conduct). I don't think 500V is enough voltage to make ice conductive enough to cause short.

In any case you would be pretty safe in the car even if that kind of electric short happens. It's like car in lightning storm. If car gets hit by lightning car chassis works like Faraday cage, and you are safe inside (lightning doesn't care one bit about being insulated off ground, it has already traveled through air for several hundred meters, so that 10-15cm doesn't matter one bit). Battery shut down is more a safety measure for really getting submerged under water, protecting both battery and passengers.

SunCoulombs | 15 September, 2013

It would be much more interesting to know how you could escape, if you are submerged in a lake and the doors are locked. Due to the increased weight in any case is not much time for that.

pmilkman | 15 September, 2013

On the submerged escape question, I'm not sure how it would be different than any car with electric windows and door locks.

Without a mechanism to break glass, you would have trouble getting out of a suddenly, fully submerged situation...but that's true of any modern car.

Probably best not to turn your Tesla into a submarine. Musk will be building those sooner or later anyway.