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Comment by hugh3 | Hacker News Reader

Interesting, but severely lacking in technical details.

What kind of batteries does this car use? How expensive are they? What kind of special-purpose charging infrastructure is required? Have any crazy tradeoffs been made in order to make this possible (for instance, does the battery die after a few dozen charge cycles?)

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Batteries have a current limit that is defined based upon the capacity of the battery. Typical low-cost lithium iron phosphate batteries (which is the chemistry looks like they are using here) usually claim a top current limit of 10C, which would allow a full charge in just over 6 minutes. Really great lithium phosphate batteries can give you a current limit of 30C or higher, which basically means your charging times are limited by how large you want your battery wires to be. This is true for most electric cars.

The only reason a Tesla Roadster can't charge in 2 minutes is because Tesla didn't want to / couldn't engineer a low cost solution that dealt with customers buying two packs (one for the garage, one for the car), which were connected by a wire doing thousands of amps at many hundreds of volts. That kind of connection can be literally explosive, much less potentially fatal to creatures that use electricity to regulate their internal fluid pumps. It's all about how fast you can shove electrons down a wire, and very little to do with the batteries themselves for this kind of pack. Rewiring a pack in parallel to put out / accept that kind of current is trivial.

Doesn't this kind of fast charging although severely reduce the life of the battery? It sounds like a solution made for gas stations to transition to. Most people wouldn't mind waiting 6 minutes to fill up their car, it takes most people 3-5 minutes already to fill a tank.

That depends on the ability of the battery to get rid of excess heat, the surface area where the exchange takes place and the thickness of the electrodes.

If all these are designed with a very rapid charge regime in mind there need not be an issue.

stolen from slashdot, which stole it from the comments in tfa:

Translated from this page: http://adacemobility.wordpress.com/2010/10/26/das-wunder-von... [wordpress.com] "Technical Data Audi A2 DBM * * Subject Empty weight (including driver) 1260 kg Perm. Total weight 1600 kg Battery lithium-iron-polymer (260 Ah/380 V) cell voltage of 3.8 volts Battery weight about 300 kg Charging time about 4 hours due to mains phase current in the household (380) battery requires 6 minutes (future solution) Life time 2500 charge cycles (without loss of capacity) = Service life target: 500,000 km Top speed 160 km / h 5-speed sequential gearbox (race gear: shifting without the clutch) E-motor 300 Nm torque" So, the 6 minute charge is future/theoretical limits of the battery. The actual time is 4 hours; which is still very impressive. Sincerely, Neil

That's a respectable amount of torque. My main concerns were power and range and they seem to have fixed a lot of these, I could see myself owning an electric car for my next.

(260 Ah/380 V)

Please correct me if I've got the math wrong. I'm not really familiar with this area.

260 Ah/380 V = 98,800 Wh, or 98.8kWh

Though I don't pay my own electricity bill, I looked the rate up for here in Halifax[1] and the rate is CAD$0.11796/kWh (flat rate).

That means you could charge this for about CAD$11.83. Not too shabby.

Also, if I'm reading this right, there is another option to pay based on time-of-day usage. The 11pm-7am option is CAD$0.06028/kWh[2], making the total roughly CAD$5.98 per charge.

[1] - http://www.nspower.ca/en/home/aboutnspi/ratesandregulations/...

[2] - http://www.nspower.ca/en/home/aboutnspi/ratesandregulations/...

As soon as everybody would start driving EVs that price will not remain though, after all increasing demand would surely drive up the price.

We currently have large excesses of power at nighttime, (production cannot be scaled down and back up in a 24hr period) so the effect could be mitigated by that.

Agreed, a six-minute charge is a delightfully vague term. It's like saying a car only requires a 12v battery to start, it doesn't give any relevant information. I tell you it's delivering it at between 20-40 amps (for the starter motor) and has over 100 Ah it's very different than the 1100mAh of a cheap battery.

It's like saying I can fill a pool in 6 minutes, it provides no relevance. Am I using a 6" pipe from a water truck, or am I using a garden hose?

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