We commonly get people asking if they should be concerned about the State of Health (SoH) of the battery in their Leaf or eNV200 dropping by several percent just after they have purchased it. In many cases this is an expected result of the method of charging changing from primarily fast charging (very common in Japan) to slow charging. This is illustrated in Figure 1 below, showing how sequential fast charges cause SoH to increase, perhaps by as much as 8%. When slow charging is resumed, SoH then drops back down. There is also often normal variation in SoH of about 1-2% even when the Leaf or van is continuously slow or fast charged.
Figure 1: Battery State of Health (SoH) as a function of odometer. There is large variation in SoH, especially with sequential fast charging. Even when only slow charging there is still variation on the order of 1-2%.
Hence if you do experience a drop in SoH following purchase, or see variation over time, this can be normal behaviour. When buying a car it can be useful to take into account that the SoH may drop by several percent post purchase if after a car with a certain SoH.
Daniel Myall, Henrik Moller, Dima Ivanov