Some time ago, I contacted a company in Europe that is making a combination 
supercapacitor that has a electrolyte in it like NiCads or KOH that has a slow 
discharge rate like a battery.  

 

These are very large units which are about 15 inches wide by about 30 inches 
long and 12 inches high.  They are design to be used in street buses which fill 
up the compartments below the passenger compartment.  The range was between 10 
to 20 miles, depending on the terrain and the number of stops.

 

Back at the bus barn, the battery pack was charge at about 300 amps at a very 
high voltage which took between 10 to 15 minutes.  

 

I got a quote from the company of how many modules it would take to replace 
thirty each 250 ah 6 volt batteries and to fit in the same area of the 
batteries.  

 

The factory cost was $39,000.00 for the modules which would gave only a 20 mile 
range and a charge time of about 5 to 10 minutes with a 12kw charger. 

 

For me, this was not cost effected. 

 

Roland        


----- Original Message ----- 

From: EVDL Administrator via EV<mailto:[email protected]> 

To: Electric Vehicle Discussion List<mailto:[email protected]> 

Sent: Saturday, May 09, 2015 9:31 AM

Subject: Re: [EVDL] StoreDot promises electric car that charges in 5 minutes



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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