Nissan Leaf battery degradation data: 24 vs 30 kWh batteries
In a recent study 283 Nissan Leafs manufactured between 2011 and 2017, had their SoH (State of Health) measured 1.382 times. The data is from 82 Nissan Leafs with 30 kWh batteries and 201 with the 24 kWh variants.
The study has some interesting conclusions and I recommend you to read it (only 14 pages), but in this article I’ll focus on one:
- 30 kWh batteries are more affected by charge/discharge cycles (distance traveled) while 24 kWh versions were more affected by time.
Why are 30 kWh batteries more affected by charge/discharge cycles?
It’s not surprising that the 30 kWh versions suffer more from charge/discharge cycles, since they are more often charged to 100 %. Remember that the option to limit the charge to 80 % was removed when the 2014 model year debuted (to game EPA range ratings). This means that none Nissan Leaf with the 30 kWh battery has this option.
If you want to improve your electric car battery lifespan, you should know that it’s better to charge to 80 % and discharge till 0 % than to charge to 100 % and discharge to 20 %. Nonetheless, if you can use the battery between a SoC (State of Charge) of 80 and 20 % even better… And if you really want to take care of your battery, try to use it only between 70 and 20 %.
Moreover, having the battery sitting at 100 % SoC is worse with the 30 kWh version than it’s in the 24 kWh variants. Because in the same conditions the 30 kWh battery will likely be hotter. In the 24 kWh battery pack, each module has 4 cells, while in the 30 kWh variant there are 8 cells per module. A more dense battery pack will dissipate heat more slowly.
Why are 24 kWh batteries more affected by time?
It’s also not surprising that the 24 kWh versions are more affected by time and older Leafs show much higher degradation levels, since the “lizard” battery only arrived in 2014 with the 2015 Nissan Leaf.
- 24 kWh battery (model years 2011-2014): higher degradation levels
- 24 kWh battery (model years 2015-2016): lower degradation levels (“lizard battery”)
While the “lizard” battery cells remained with LMO cathodes, they had the electrolyte improved to be more heat tolerant. Only in 2016, Nissan finally started using NCM cathodes in their battery cells with the introduction of the 30 kWh battery version.
Anyway, I think that this information is important if you plan to buy an used Nissan Leaf. Choose wisely.
Thanks “Leaf Owner” for the heads up!