The advantage Tesla has relative to most other EVs is having large packs.
The difference in maximum power not attributable to pack size is mostly* explained by superior cooling in the Tesla.
[…]
*There is also some difference in cell chemistry and perhaps pack resistance but I don't know those details
Ok, so “the advantage” you said before was large packs, but now what’s not attributable to pack size (e.g. as I already noted the smaller battery SR charges faster than a larger battery Hyundai or Kia) is attributable to superior cooling. I just said that, so you are agreeing with me now?
The massive parallel cell design is what allows for more cooling!
3p96s has WAY less cooling surface area than a 46p96s, so the Tesla packs can take higher current while safely keeping temperatures within spec with active cooling.
Meanwhile a 2p96s Leaf with air cooling only would probably melt if it took 250kW V3 supercharger rates
What’s the difference here? Pack architecture! Even liquid cooled systems that are only 3p can only cool so much surface area. And...
Since the 96S stays constant, as the pack grows in size the extra cells are placed in parallel. That is true for any and every EV on the market today.
No,
this is not
necessarily true for every EV on the market. It’s true for Teslas, more specifically within a pack family of Teslas like S/X (18650) or 3 (2170), but it’s absolutely NOT the case “for every EV on the market today”.
You can increase capacity by increase the cell pouch sizes used in each module that’s in series
without adding cells in parallel. The simplest example of this is the transition from the S with
more smaller cells to the 3 with
less larger cells. An example of it
not being true across Teslas themselves
Anyways, thanks for bringing this up and making me look up the Leaf, because the quote direct from Nissan below illustrates my point exactly with the advantage Tesla has with massively parallel 31 or 46 cell charging that splits the input current across all those cells in parallel and reduces heat much more than possible with just 2p or 3p like the Leaf:
“Nathan Herbrandson, Nissan’s vehicle program development manager for EV marketability, during a recent press event for the 2019 Leaf Plus in San Diego, California.“
[…]
“The key here is that number of cells that we have in parallel,” he said. “Previously, with the 40-kWh pack, we had 96 cells in series, like in a flashlight. In the previous generation we had two of those ‘stacks,’ if you will, of 96 cells. So you’re going from two layers to adding a third layer. That reduces your resistance. You can imagine drinking a glass of water. If you have one straw, you have some resistance from the straw. If you use two straws, you get less resistance, and reducing resistance obviously means you’re creating less heat.”
So. 46p LR better than 31p SR, much much better than 3p Leaf+, better than prior 2p Leaf.
Why? Less current, less resistance. Heat is I-squared R.
More surface area = more cooling. (vs Hyundai/Kona who use liquid cooling like Tesla, never mind silly Nissan with air cooling).
Tesla’s pack architecture allows for LESS heat to be produced AND more cooling. This is their advantage in charging speed.
Not Superchargers vs CCS DCFC. Not large pack size.
Source:
Updated Nissan Leaf Battery — 50% More Battery | CleanTechnica
