Tesla Motors Club
This is my first post on the forums, what a fantastic community!
My question relates to Tesla's fast charging of Panasonic cells.
Every spec sheet that I've seen from Panasonic lists the maximum charge rate as 0.5-0.7C. With Tesla's 120kW Superchargers, they would be charging at 1.41C. Are they accomplishing this through active thermal management? Surely you can charge a battery faster than its suggested charge rate, but I would expect reduced lifespan of the battery. Is temperature management the only thing that limits the maximum suggested charge rate of these cells?
It's my understanding that the Model S uses the Panasonic 18650PF cell, which has an DC resistance of around 43 mOhms. Other 18650 cells in the industry with similar internal resistance numbers are rated for a 1C max charge rate. I'm wondering if Panasonic is rating their cells to a reduced charge rate in order to maximize cycle life to 80% of initial capacity.
I expect that because Tesla is using a liquid cooling system, it can safely support a faster charge rate, with minimal added stress on the cells. I imagine that the standard 0.7C rate is with the expectation that most applications of this cell are for power tools in sealed enclosures, so the charge rate is reduced to manage temperature, and increase safety margins since cooling is only passive.
Can any one firm up my speculations?
Cheers,
Tommy
My question relates to Tesla's fast charging of Panasonic cells.
Every spec sheet that I've seen from Panasonic lists the maximum charge rate as 0.5-0.7C. With Tesla's 120kW Superchargers, they would be charging at 1.41C. Are they accomplishing this through active thermal management? Surely you can charge a battery faster than its suggested charge rate, but I would expect reduced lifespan of the battery. Is temperature management the only thing that limits the maximum suggested charge rate of these cells?
It's my understanding that the Model S uses the Panasonic 18650PF cell, which has an DC resistance of around 43 mOhms. Other 18650 cells in the industry with similar internal resistance numbers are rated for a 1C max charge rate. I'm wondering if Panasonic is rating their cells to a reduced charge rate in order to maximize cycle life to 80% of initial capacity.
I expect that because Tesla is using a liquid cooling system, it can safely support a faster charge rate, with minimal added stress on the cells. I imagine that the standard 0.7C rate is with the expectation that most applications of this cell are for power tools in sealed enclosures, so the charge rate is reduced to manage temperature, and increase safety margins since cooling is only passive.
Can any one firm up my speculations?
Cheers,
Tommy