120 Chapter 10 HEV Temperature Example 45 35 40 Temperature (°C) 30 20 25 10 15 5 0 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 1680 1800 Time (seconds) Figure 3 HEV temperature example. the temperature down below the ambient in order to ensure life, performance, and against catastrophic failure. Constant operation at high temperatures reduces cell life and speeds the aging process. This was demonstrated in 2012 when a group of Nissan Leaf owners in the Arizona region complained to Nissan about the low electric range and reduced battery capacity that they were getting with their vehicles after only a short period of time (Gordon- Bloomfield, 2012; King, 2013).
While there were not initially many of these complaints, there were enough to generate much unwanted national media attention for both Nissan and the industry in general. In the end, Nissan responded to these criticisms in an open letter on their MyNissanLEAF.com forum stating that: Battery capacity loss of the levels reported may be considered normal depending on the method and frequency of charging, the operating environment, the amount of electricity consumed during daily usage and a vehicle’s mileage and age. (Carter, 2012; Bailo, 2012) They then went on to state that:
Battery data collected from Nissan LEAFs to date currently indicates that less than 0.3 per- cent of Nissan LEAFs in the U.S. (including vehicles in service dating back to December, 2010) have experienced a loss of any battery capacity bars. Overall, this universe of vehicles represents a very small fraction of the more than 13,000 Nissan LEAFs on U.S. roads. Also, data received globally from other LEAF vehicles shows that this condition typically occurs to high-mileage cars or those in unique operating situations.
(Bailo, 2012; Carter, 2012) In essence, Nissan’s evaluation of the vehicles and the way they were being used found that the users who were experiencing this reduction in capacity tended to be driving about 150% of the average US annual mileage, some of whom were also using frequent fast charging.