JRP3

To me the big advantage of the NanoSafe is the potentially longer lifetime than other lithiums. If they really can last 20 odd years and thousands of cycles then the initial cost is less problematic. The fast recharge potential is a marketing bonus for now, until there are more high powered EV "filling stations".

tonybelding

I agree. . . The biggest selling point is their long service life. Thermal safety and stability are also important. So, you shouldn't have to isolate each cell in its own containment structure, and your need for cooling is reduced: air cooling could be practical.

My understanding is that NanoSafe batteries have considerably less energy density than standard Li-ion cells, but it's much more even across a wide range of temperatures. Again that translates to less temperature control equipment -- less "coddling" required.

malcolm

Long service life for the A123s is impressive, so long as you discharge up to about 2.42 C rate.

5A/ (90% efficiency x 2.3 Ah) = 2.42 C

http://www.a123systems.com/newsite/p..._FEB2007-1.pdf

The other question I have is, what is the variation between supposedly identical cells? Is it like this?

http://www.ibt-power.com/Battery_pac...Ion_CycGph.JPG

The above graph is a discharge at 1C to 2.75V, +25ºC.

vfx

"Altairnano as used by Phoenix Motorcars, Zap, and Lightning.
...
No need for sealed, managed storage systems because they are more inherently stable. "

Something I've not mentioned in several months but it was more about attitude than technology (more in a later post).

I saw the Pheonix at an auto show and quized a few of the folks there. The sales guy went on about their superior batteries and that they did not need a cooling system.

We were looking under the hood and I pointed out the car's radiator. In an elecrtic car? Turns out that their inverter needs cooling.

I don't know but maybe all that power going in so fast generates some heat.

malcolm

But if the currents through the inverters are sufficient to require cooling that must mean a big battery pack, allowing low C rates per cell, reasonable temperatures and minimal coddling.

The Volt approach seems to be limit everything to 53 kW. Well at least, that seems to be the figure for the generator, which is only allowed to charge the A123 16kWh pack up to 80% capacity maximum (12.8 kWh). A full charge can only be achieved through the more stable domestic socket. Presumably they won't limit the motor to 53 kW, will they?

TEG

I think you could probably engineer things different ways.
With more expensive parts you could probably build a more efficient inverter that generates less waste heat. Or you could use parts that could stand up to higher temperature. Or you could air cool it (as Tesla does).

Design decisions have to be made for the batteries, inverter/controller, and the motor itself. The eMotor on my RangerEV is water cooled, yet it makes only 1/3 the HP of the air cooled Roadster motor.

Someone I know at the Palo Alto EV rally was talking about devices with more or less "thermal mass". Basically you can engineer in passive heat dissipation. If you have enough material to conduct, transport and dissipate heat then you don't necessarily need active cooling systems.

JRP3

Here's something I've wondered about. What takes more mass and/or energy, passive cooling designed into the system or liquid cooling? I'd think that liquid cooling would be more efficient than adding surface area and mass for passive cooling since that extra mass has to be moved by the battery pack, but I don't know for sure.

JRP3

Altair speaks:
http://link.brightcove.com/services/...ctid1180952593

TEG

Along with Phoenix, they mentioned "ISE" as a partner/customer.

ISE Corp and Altair Nanotechnologies developing lithium batteries together - AutoblogGreen

...No mention of Zap!...