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To: thackney

They’re working on the wrong problem. It’s the long recharge time not range that is the problem. I wouldn’t mind a 200 mile range limit if I could recharge in 5 minutes.


48 posted on 02/11/2015 6:31:48 AM PST by central_va (I won't be reconstructed and I do not give a damn.)
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To: central_va
I wouldn’t mind a 200 mile range limit if I could recharge in 5 minutes.

A little quick math shows why that's probably not going to happen any time soon...

At 20 mpg, a car uses about 333 kWh (kilowatt-hours) of thermal energy - in the form of gasoline - to go 200 miles, as you suggest.

If we assume the engine and power train are about 15% efficient, that's 50 kWh of actual mechanical energy delivered to the wheels.

To put 50 kWh of electrical energy into a battery - at a recharging station - in five minutes, would require

50 kWh * 12 = 600 kW

of electrical power. That's a bit more than 2700 amps at 220 volts. The factor of 12 is because five minutes is one-twelfth of an hour.

And that's assuming that electric vehicles are 100% efficient from the charging station to the wheels on the road. They're actual efficiency is quite a bit less than that. I would guess that an overall efficiency of 80% is probably being generous. That would raise the current needed to charge you up in five minutes to about 3400 amps at 220 volts.

Keep in mind that the typical arc welder operates at something like 400 amps. Picture the cables and connectors used for a normal shop-floor arc welding setup. Now multiply the size (area) of those cables and connectors by almost nine, and you've got the size of the cables you'd need to carry the current necessary to charge your car in five minutes.

Not to mention that six or seven hundred kilowatts is probably something like twenty times more than a typical gas station uses overall, and then multiply that by four or five cars wanting to rapid-charge at the same time, and you can see the problem.

86 posted on 02/11/2015 10:22:38 AM PST by Steely Tom (Vote GOP for A Slower Handbasket)
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To: central_va

DC quick Chargers will allow you to recharge in less than 30 minutes now and remember with electric vehicles you pull out of the garage every morning with a full tank so you only need to rely on public charging stations on long trips also remember with Tesla the super chargers are always free and even the DC quick chargers that are not free are very cheap compared to gasoline on a per model basis right now I Drive a large gasoline burning SUV and if somebody told me I can wait for 20 minutes and fill up for free or a couple of dollars instead of by waiting 5 minutes for a $50 fill up at a regular gasoline pump I would take the 20 minutes everyday.


114 posted on 02/12/2015 1:53:48 AM PST by NavVet ("You Lie!")
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