2017-05-14

Elementary physics, dear Watson, elementary physics...

Elementary physics, dear Watson, elementary physics...

It's funny when people ignore very basic physics, like with this battery. When I say this is impossible, I'm sure there will be plenty of people pointing out that this battery uses new materials of which I have no knowledge, that they may use a new structure of which I equally have no knowledge etc. However, they miss the point.

The point is to get about 85kWh ("300 miles") through a cable within five minutes. Tesla is using batteries with 375V. Let us assume we charge directly with 400V (Hello Europe!), not 270V or even less. Let us also assume 100% efficiency, since we are dreaming anyway.

At 400V the 85kWh pack needs 212.5A for one hour to be charged. They want to do it in five minutes, so we need 12x the current, which is 2,550A. I searched for a gauge calculator that would accept this current, but I couldn't find any. Even assuming three "phases" (Let's stick to DC for simplicity.) we still have 850A, which for a cable with 1m length (rather short for charging) require 300mm^2. That is a block of 20x15mm copper. Plus insulation. And you need three pairs of those.

So, this marketing dream fails at something as simple as a cable. It isn't the first to do so. And neither will it be the last. Because, who needs physics?
http://gas2.org/2017/05/13/elecrtric-car-battery-300-mile-range-5-minute-charging-time-israeli-company/

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