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> Nissan Leaf had no battery management system when it launched. Citation needed? As far as I know even the 2012 Leafs had a per cell thermal management. I t

> Nissan Leaf had no battery management system when it launched. Citation needed? As far as I know even the 2012 Leafs had a per cell thermal management. I think in the earlier Leafs a lot of the intelligence on charging operation and battery cooling/heating was offloaded to the BCM module but it is a bit of a hyperbole to say that there was no battery management. They may not have had a dedicated BMS module in the OEM sense of BMS (like what Infineon now makes) but they certainly had temperature/charge management controls.

jnsaff2 4y ago
There is thermal management and then there is thermal management. Nissan leaf had cell level voltage and temperature monitoring, it also had a rudimentary heating element that would not let the battery freeze solid. Its battery also was poorly designed so some of the cells had worse conditions than others and the batteries "died" because a few cells went out of limits and the BMS would limit the performance/range of the car. The rest of the cells could go much further. Also you should never charge lithium batteries (other than LTO) below freezing as it forms crystals that are lost to the capacity. Leaf did not to my knowledge compensate for this. Moreover 24kWh battery doing 1000 cycles is about 100 000 km of driving. Then there is Tesla batteries that have liquid cooling and heating of the whole pack. Battery is never charged below freezing, also above freezing the charging is adapted to the cell temperatures and for fast charging the battery temp is raised up to 60C, above 65C the cooling kicks in. The batteries are much larger in Teslas, typically say 80kWh. That combined with better efficiency, better battery management, lower power draw per cell, etc means that they get more than 1k useful cycles out of it. Say 2k (tho they claim more, and there is considerable variability due to use and environment). So 500km * 2k cycles is 1 million km. The battery may degrade due to age before it reaches its cycles. Also as mentioned above. Tesla does draw up to 300kW out of the battery. The onboard AC charger is 11kW so if that is bidirectional then the it is really gentle on the battery. That said, I'm not dissing Nissan, they were truly innovative and we owe them lots of gratitude for popularizing EV's and they have also evolved their tech considerably. Others are doing battery management very well as well nowadays.

jnsaff2 4y ago

There is thermal management and then there is thermal management. Nissan leaf had cell level voltage and temperature monitoring, it also had a rudimentary heating element that would not let the battery freeze solid. Its battery also was poorly designed so some of the cells had worse conditions than others and the batteries "died" because a few cells went out of limits and the BMS would limit the performance/range of the car. The rest of the cells could go much further. Also you should never charge lithium batteries (other than LTO) below freezing as it forms crystals that are lost to the capacity. Leaf did not to my knowledge compensate for this. Moreover 24kWh battery doing 1000 cycles is about 100 000 km of driving. Then there is Tesla batteries that have liquid cooling and heating of the whole pack. Battery is never charged below freezing, also above freezing the charging is adapted to the cell temperatures and for fast charging the battery temp is raised up to 60C, above 65C the cooling kicks in. The batteries are much larger in Teslas, typically say 80kWh. That combined with better efficiency, better battery management, lower power draw per cell, etc means that they get more than 1k useful cycles out of it. Say 2k (tho they claim more, and there is considerable variability due to use and environment). So 500km * 2k cycles is 1 million km. The battery may degrade due to age before it reaches its cycles. Also as mentioned above. Tesla does draw up to 300kW out of the battery. The onboard AC charger is 11kW so if that is bidirectional then the it is really gentle on the battery. That said, I'm not dissing Nissan, they were truly innovative and we owe them lots of gratitude for popularizing EV's and they have also evolved their tech considerably. Others are doing battery management very well as well nowadays.