Breaking Down Tesla's Battery Day with Ravi Kempaiah

PTFC Brian

New Member
https://insideevs.com/news/446430/video-tesla-battery-day-phd-scholar-ev-researcher/

I love my ST2, but I also follow several EV sites, and its really fun to see the cross-over in technology between bicycles and cars (planes and boats). But, this was especially exciting to see the recent interview with Ravi. Please see the attached link.

Ravi is far too modest, however his energy storage knowledge and research is very impressive! After Tesla's Battery Day, I didn't quite understand how and why the improvements to the electron path in the new tab-less 4680 battery worked. Ravi does a fantastic job of explaining as well as breaking down the new efficiencies.

Hopefully this battery can make its way to future Stromers.
 
I watched the video and it was very informative.

Ravi, on a real world example:
The top shelf Stromer battery is 983 wh and is quite heavy and is certainly expensive at $2000.

If 4680 batteries were used in that sized shell (as close as possible):
What watt hours could it have?
What comparative weight, 60%?
What cost is possible?

It would be amazing to have much more energy stored in much less weight and much less expensive!!
Thanks for all your work on this issue!
 

bluecat

Well-Known Member
The top shelf Stromer battery is 983 wh and is quite heavy and is certainly expensive at $2000.

Only a few year ago, German battery assembler claims the 21700 cell to be the future. Now, Tesla comes up with a 46mm x 80mm cell, which will increase the problem: The dead volume.

Of course, this is a problem only for the E-Bike industry, not for the automotive. Take the current Strommer battery and guess, how many 4680 cells might have space. So you see, energy density is not all. Currently, some brands offer dual battery systems. This means, taken two batteries out for recharging every time. Not the way of easy commuting.

How must the downtube be shaped to offer enough space for so many 4680 cells that the capacity ist clearly higher than 1 kWh? The new ST5 will come with a broader top tube, maybe the downtube will be reshaped for other cells than the 18650.

The swiss brand Speedped offers a 2.4kWh battery:
 

Ravi Kempaiah

Well-Known Member
https://insideevs.com/news/446430/video-tesla-battery-day-phd-scholar-ev-researcher/

I love my ST2, but I also follow several EV sites, and its really fun to see the cross-over in technology between bicycles and cars (planes and boats). But, this was especially exciting to see the recent interview with Ravi. Please see the attached link.

Ravi is far too modest, however his energy storage knowledge and research is very impressive! After Tesla's Battery Day, I didn't quite understand how and why the improvements to the electron path in the new tab-less 4680 battery worked. Ravi does a fantastic job of explaining as well as breaking down the new efficiencies.

Hopefully this battery can make its way to future Stromers.

@PTFC Brian and @MinnBobber ,

Many thanks for the kind words.

What was unveiled at the battery day event was so impressive on so many levels. For the last 3 decades, cylindrical cells were done in a very similar way. But, Tesla is radically re-thinking the battery design from all angles. This is very akin to the iPhone moment when Steve Jobs announced touch screen based interface, iOS eco-system and a deep vertical integration within the company that completely changed the phone industry.

With the new 4680 cells, Silicon anode, Lithium extraction, cathode production and Tera factories .... Tesla is doing something similar. IF they succeed at this, it will change the landscape of electric transportation and energy storage forever! Because once the cost of a battery pack is less than $100 USD /kWhr, it completely changes the equation of manufacturing and service. Those companies that don't adapt and change, will become like Nokia and Kodak.

I don't think we will see 4680 cells in E-bikes anytime soon. In about 4-5 years, other manufacturers like LG, Panasonic and Samsung will adopt something similar.
Perhaps we will see 1kW battery packs weighing ~70% of what it is today and that would mean a weight reduction is 2-3lbs for a Stromer battery.

Really optimistic about the future of EVs and it's possible because of early adopters and enthusiasts like you.
 
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FlatSix911

Well-Known Member
https://insideevs.com/news/446430/video-tesla-battery-day-phd-scholar-ev-researcher/

I love my ST2, but I also follow several EV sites, and its really fun to see the cross-over in technology between bicycles and cars (planes and boats). But, this was especially exciting to see the recent interview with Ravi. Please see the attached link.

Ravi is far too modest, however his energy storage knowledge and research is very impressive! After Tesla's Battery Day, I didn't quite understand how and why the improvements to the electron path in the new tab-less 4680 battery worked. Ravi does a fantastic job of explaining as well as breaking down the new efficiencies.

Hopefully this battery can make its way to future Stromers.

Great video... here is the direct link. ;)

 

bluecat

Well-Known Member
With the new 4680 cells, Silicon anode, Lithium extraction, cathode production and Tera factories .... Tesla is doing something similar. IF they succeed at this, it will change the landscape of electric transportation and energy storage forever! Because once the cost of a battery pack is less than $100 USD /kWhr, it completely changes the equation of manufacturing and service.

I believe, the cheaper manufacturing costs will be key. The, higher energy density will become available not only for experimental sailing planes. At the time, german automotive industry has no clear target in terms of EV. They add batteries and electric motors to conventional cars. This end up in heavy weight and low range.

But I'm also aware of Mr. Musk always spectacular announcements. $ 35'000 for a Tesla Model 3 - and as it finally reached Switzerland, the entry price was around 55'000 CHF. Even today, the entry price is still 45k CHF. With other words: I would be happy if a breakthrough in battery technology takes place - but I will believe, when its there.