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 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
