There’s another reason why Nissan developed its own battery – cost. Nissan Leaf is intended as a production vehicle for the general consumer, so it needs to be sold at a price affordable for most drivers. Cutting the cost of the battery is key to reducing the overall costs of the car.
Miyamoto joined Nissan in 1981. Following involvement with development of batteries for one of Nissan’s earlier EV efforts, the Nissan Altra, Miyamoto then became the engineer responsible for creating Nissan Leaf’s battery.
(EV) Experience makes a difference
And before Leaf went on sale, experiments were conducted for over a year with a prototype vehicle in Arizona, California, New York, Detroit, and other places, in order to test if the data acquired from the previous EVs actually worked as expected in reality.
A battery without a cooling system?
When a battery has a cooling system, then more space and cost are also needed to install the system, and that can also mean a vehicle that costs more and a battery that deteriorates faster. In a nutshell, a battery without a cooling system has more merits for the customer.
A battery that can control its heating temperature without a cooling mechanism is also longer lasting, since the biggest cause of a battery’s lifespan being shortened is overheating. In other words, having a cooling system to lower the temperature of a battery in case of overheating has adverse effects on the battery’s durability – it’s better to engineer a battery system that works to avoid overheating to begin with.
A laminated structure for layout flexibility
The structure is thin but with a wide surface area, making for superior heat release qualities, and a major reason why the Leaf battery system does not need a special cooling mechanism.
The biggest challenge for the battery development was whether such a slim laminated battery cell design could actually work as part of an automobile in reality. Developed in partnership with a laminated film manufacturer, the lamination material was selected after looking at different varieties of plastic and thickness, and eventually a special lamination was developed just for Nissan Leaf. In the years leading up to Leaf going on sale, the reliability of the lamination was checked on test cars, before the right material was found for the final model.
A battery working with the whole car body
Take the safety performance in case of collision. Of course, this means possessing sufficient durability if the battery itself suffers an impact. In addition, body structure also plays an important role. By carefully designing the vehicle and battery structures, it becomes possible to provide a larger battery mounting space and maintain safety performance.
An EV battery that only a carmaker could create
To give an extreme example, if we take out the back seats of the car and load more batteries it is, of course, possible to further extend the cruising distance range of the vehicle. However, Nissan Leaf is a five-seater, and is setting the standard for the post-gasoline car era’s EV vehicles for the general consumer. Due to the spread of EVs, now you can sometimes hear people talk about how, if you just have a motor and battery then anyone can build a car these days – not just carmakers. “Well, yes, you can ‘build’ a car,” explains Miyamoto. “But I always want to say to them that they should try making one to the level of Leaf! With an EV, you also need to ensure the safety of your passengers.”
A safe and secure EV could only be created since its makers thought holistically, creating a car design that considers the entire vehicle: Not the battery technology by itself, but also a car body, motor and controls that work in tandem with the battery. That is why Nissan is pouring its energies into developing fully intuitive and integrated EV batteries.
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