Probable Base Price?????
07-17-2017, 06:14 PM
#31
It is a huge voltage drop and a huge power loss, with a correspondingly high cooling requirement. It's a fact of life for high performance EVs (which the Leaf is not by any definition). And why would they ever report that info publically? It's competitive advantage territory.
We tested various discharge rates and states of charge. The cells individually bottom out at about 42mOhm for really low discharge rate, 45mOhm+/-1mOhm for typical discharge rates and 20%-90% SOC, and go as high as 70mOhm at low states of charge.
There are cells with lower impedence, but they universally have lower energy as well, because there's a tradeoff between metal volume (low resistance, no energy) and jelly roll volume (high resistance, high energy).
We tested various discharge rates and states of charge. The cells individually bottom out at about 42mOhm for really low discharge rate, 45mOhm+/-1mOhm for typical discharge rates and 20%-90% SOC, and go as high as 70mOhm at low states of charge.
There are cells with lower impedence, but they universally have lower energy as well, because there's a tradeoff between metal volume (low resistance, no energy) and jelly roll volume (high resistance, high energy).
07-17-2017, 10:57 PM
#32
Instructor
I'm not going to share company proprietary reports and such, even heavily redacted. I personally did the experiments, as did several of my colleagues at 2 companies - who have themselves worked at every company that's publicly announced an EV product - and those were the numbers we were seeing.
If you have a non-proprietary source that says otherwise, of course, please feel free to share, but I stand behind my research and my teams.
If you have a non-proprietary source that says otherwise, of course, please feel free to share, but I stand behind my research and my teams.
07-18-2017, 01:21 PM
#33
I'm not going to share company proprietary reports and such, even heavily redacted. I personally did the experiments, as did several of my colleagues at 2 companies - who have themselves worked at every company that's publicly announced an EV product - and those were the numbers we were seeing.
If you have a non-proprietary source that says otherwise, of course, please feel free to share, but I stand behind my research and my teams.
If you have a non-proprietary source that says otherwise, of course, please feel free to share, but I stand behind my research and my teams.
could use improvement:
Re - Nissan's effective overall battery impedance
Rs - Nissan's single cell battery impedance
Re = Rs X 96 / 20, where Re = 56 millohms (new @ 30 C)
Rs = Re / 4.8 = ~ 12 mohms
The Leaf's max motor current is about 225 - 250 amps which results in only about
only a 15 volt battery voltage drop compared to the Tesla's voltage drop at 1000 amps
of about 60 volts (poor efficiency).
If these data are accurate, it's time for Elon to use those SpaceX physicists on Tesla's battery technology.
07-18-2017, 11:24 PM
#34
Instructor
Well, if your Tesla data are correct, Tesla's battery technology (Panasonic) compared to Nissan's
could use improvement:
Re - Nissan's effective overall battery impedance
Rs - Nissan's single cell battery impedance
Re = Rs X 96 / 20, where Re = 56 millohms (new @ 30 C)
Rs = Re / 4.8 = ~ 12 mohms
The Leaf's max motor current is about 225 - 250 amps which results in only about
only a 15 volt battery voltage drop compared to the Tesla's voltage drop at 1000 amps
of about 60 volts (poor efficiency).
If these data are accurate, it's time for Elon to use those SpaceX physicists on Tesla's battery technology.
could use improvement:
Re - Nissan's effective overall battery impedance
Rs - Nissan's single cell battery impedance
Re = Rs X 96 / 20, where Re = 56 millohms (new @ 30 C)
Rs = Re / 4.8 = ~ 12 mohms
The Leaf's max motor current is about 225 - 250 amps which results in only about
only a 15 volt battery voltage drop compared to the Tesla's voltage drop at 1000 amps
of about 60 volts (poor efficiency).
If these data are accurate, it's time for Elon to use those SpaceX physicists on Tesla's battery technology.
We're getting close to the point at which the additional energy per cell is offset by the increase in resistance and corresponding efficiency drop, but we're not there yet, and there are some new chemistries that may be promising in a few years. In the meantime, though, Sony, LG, Samsung, and Panasonic are all focusing on packing incrementally more energy into the same volume with as little of a resistance hit as possible, because that's what most high-performance and road-trippable EVs demand.
Or, as the shift from 18650 to 21700 occurs, fit 30-50% more energy in 46% more volume at 60% the resistance.
07-21-2017, 05:59 PM
#35
I don't see how 20,000 move at this price, which leans Panemera. The Germans have employed natual demand limiters in what they electrify. It doesn't look like a small battery, this time. The suicide doors probably ought to go. A lot else to find out, yet.
On the up side, one can imagine Porsche installing several of its 350KW chargers at race tracks. 20 minute DE sessions could use ~40KWh ea, and be topped off in as fast as ~7 minutes.
In the flesh I could see buying this car, but I can't see waiting as the trust level isn't there.
On the up side, one can imagine Porsche installing several of its 350KW chargers at race tracks. 20 minute DE sessions could use ~40KWh ea, and be topped off in as fast as ~7 minutes.
In the flesh I could see buying this car, but I can't see waiting as the trust level isn't there.
09-16-2017, 01:52 PM
#38
I truly hope the car they build is very faithful to the concept and it meets the performance claims they're making. If it does, I'm very interested. If it just looks like a Panamera, but with an electric motor, I'll have zero interest.
09-17-2017, 12:54 PM
#40
Could not agree more. I find the concept stunning and way more appealing to me than a model S but if production time comes and there's a drastic difference I'll be more than a little disappointed
