Portable Battery Pack

Aux battery has been discussed before - any additional battery capacity is better used if included in the main battery, and the driver should pay attention of low SOC warnings issued by the vehicle.

I see the possible scenario to walk and get more juice with the portable battery, though - resembling the spare can for fuel. But would it be practical? A portable pack of 200 cells (e.g. Panasonic NCR-18650) weights 10kg (22lbs) and holds 2.4kWh - enough to move a Model S for another 10 miles. And you have to walk to the next outlet, charge it, and walk back - or get a hitch.

An Aux battery pack would not be a bad thing. Based on the previous post, a 20kg pack could squeeze out ~ 20 miles. Another application for such a pack would be testing new battery & capacitor chemistries. Not sure how TM would see this; but new battery claims can be field tested using these smaller portable packs. Eventually, these smaller packs may even rival a 300-mile pack.

STxTesla said:

To calm some of the range anxiety that Tesla owners may develop while traveling long distances, it might be a good idea for Tesla to offer a portable battery pack...

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IMO it's just easier and cheaper to get dumb sockets installed everywhere so that you can stop and recharge... wouldn't take long on a 40A socket to get your 10 to 20 miles extra range.

It would be a very good idea indeed. I can charge the extra pack from my PV, while driving around. Next day, i can charge my second one.

The aux pack cannot be used to drive the vehicle, unless it has beefy power density. This comes at a trade-in for energy density and mass/volume, both adverse for portability.
You would hook up the aux battery to the car and wait until charge is transferred to the main battery.
Eberhards idea of "charge one, drive one" appears to me like a full battery swap. If the vehicle doesn't support that, you can use two vehicles. Or if parked for longer time, you could transfer charge from a stationary battery.

STxTesla said:

Perhaps AAA will be around with charge packs in the future to assist those that run out of charge on the highways.

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http://www.foxnews.com/leisure/2011/11/07/aaa-testing-mobile-electric-car-charging-stations/

Adm said:

http://www.foxnews.com/leisure/2011/11/07/aaa-testing-mobile-electric-car-charging-stations/

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Real AC power has trucks with fast DC charging and Level 2 up to 50 Amps.
Real Power