The cells can charge in 5 minutes to 90% or better. These have been
available for years.
However, no one will pay for a charger large enough to charge a car in 5
minutes. It would cost ten or twenty times more than the car.
Such a charger would be as big as a sea container.
Bill D.
On 5/9/2015 9:31 AM, EVDL Administrator via EV wrote:
On 8 May 2015 at 19:11, len moskowitz via EV wrote:
we'll take a car that has a zero charge and recharge its batteries to
100% capacity.
Let's look at this a bit more closely.
First, let's consider how much power he needs to do this. He says his car
will go to "Beersheba and back." From Tel Aviv, that's 140 miles, a pretty
substantial range for anything but a Tesla. So let's postulate that he's
charging at the other end. Now we have 70 miles per charge. He might have
a very efficient car that can manage 100-150 Wh/mi, but let's say it's a
more typical 250 Wh/mi.
Thus he needs to put .25kWh/mi * 70mi == 17.5Wh into the EV's battery in 2
minutes. That's a brisk 525kW at the battery. Allowing for 85% charging
efficiency, he needs an electrical service that can produce about 620kW.
Seems like a lot, eh? Well, according to the Sierra Club, a typical US
Walmart Supercenter uses over 28,000 kWh per day. (Yeah, I know. I had to
pick my jaw up off the floor too.)
Assuming 24h operation, that's an average load of 1166kW. I'm not an expert
on such things, but I'd guess that it peaks at around twice that, maybe
more. Still, let's conservatively say that its peak capacity is 1500kW.
Thus the electrical service that supplies that store could charge 2 of these
cars at once.
That's still a fair bit of power, but for a demo that's probably mainly
meant to line up investors, it's quite do-able.
Second, and more importantly, I'm skeptical about the 100% claim. Eighty
percent I'd believe. But unless he's changed electrochemistry in some
pretty major ways, it's going to be really tough to charge that last 20% at
525kW without things going bang.
David Roden - Akron, Ohio, USA
EVDL Administrator
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