cromka
8 hours ago
“and claims a charging rate of up to 11 kW and with an efficiency of about 90% for easy overnight charging.”
That’s a some 9kW lost on a 80kW battery. I get the convenience, but I think the best use for those would be when standardized and installed in public parking spots, for a brief charge bump, not to charge fully at home, e.g overnight, which is what Porsche aims for.
cisc
6 hours ago
> That’s a some 9kW lost on a 80kW battery
It's about the same as wired AC charging. There are always charging losses:
https://insideevs.com/features/711659/ev-charger-efficiency-...
onetwentythree
6 hours ago
The 90% efficiency of the wireless transmission would be on top of the efficiency of typical charging (which is mostly losses after the power reaches the vehicle).
cisc
6 hours ago
It's 90% from grid to battery.
1970-01-01
4 hours ago
It is not.
It is "up to 90%"
We all know what this means in reality.
unrented7977
3 hours ago
Do we? Because if you're invoking scare quotes, I don't think you have a good grasp on what's actually happening here.
90% is pretty good efficiency at this level of power. One cannot give an exact figure because it depends heavily on environmental factors, primarily temperature. 90% is pretty much exactly what I'd expect to see in the real world under same conditions.
beAbU
5 hours ago
> That’s a some 9kW lost on a 80kW battery.
*kWh
Using the right units is important.
cheschire
4 hours ago
"This may sound like one of those overly pedantic fixations... but it's not. Power and energy are very different concepts." -Technology Connections
solarkraft
5 hours ago
It will still be 90% efficient regardless of who uses it. In fact if it is used more, the total losses will be higher.
(Some of this becomes clearer when you have a feeling for the units: kW is a measurement of power, not energy)
helsinkiandrew
5 hours ago
> not to charge fully at home, e.g overnight, which is what Porsche aims for.
Wouldn't an overnight (usually cheaper) 10+ hour charge be a great use for (slow) 11 kW charging?
joinHNtheysaid
5 hours ago
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