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Published on September 29th, 2018 | by Maarten Vinkhuyzen

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Nissan’s Long Strange Trip With LEAF Batteries

September 29th, 2018 by  


The Nissan LEAF is infamous for its battery problems. It started with the fast degrading 24kWh battery in the original 2010 Nissan LEAF. That battery was not up to the hot conditions of US Southwest states. It was replaced by a battery with a different chemistry, the 24kWh “lizard battery” in 2014. In 2015, the model year 2016 (MY2016) LEAF got a slightly larger 30kWh battery option. In the MY2018 Nissan LEAF, an even bigger 40kWh battery was offered.

2018 Nissan LEAF 40kWh

When Nissan decided to build the Leaf, it discovered a little problem. The battery production capacity it needed did not exist, and the battery makers were not willing to invest the billions of dollars needed to expand production. Nissan intended to start production with 50,000 cars per year, growing to 300,000–500,000 in about 5 years. Batteries were crazy expensive in those days. From $400kWh for the cheapest laptop batteries to over $1,000kWh for high-quality batteries good enough for use in EVs.

The only option for Nissan was to start producing its own batteries. Up until now, all Nissan batteries have been made by AESC, the joint venture Nissan and NEC started in 2010 to make electric vehicle batteries.

To reduce costs, Nissan originally opted for a small (24kWh) battery without a thermal management system (TMS). When the heat in some places caused rapid degradation because it was too much for this battery, Nissan chose a better chemistry instead of adding a TMS, expecting that it would be good enough and a lot cheaper. A TMS would require an extensive redesign of the battery pack and the surrounding area in the car.

While this new lizard battery was still having faster degradation than other car batteries in the semi-deserts of Texas and Arizona, in most of the rest of the world, the problem was gone. This did not stop purists from demanding the only real solution, a great TMS, but the number of warranty claims told Nissan that the problems were over.

That is, until the new 30kWh battery in the MY2016 LEAF started to show the same problems as the original LEAF battery, but only worse this time. The rapid degradation of the battery is shown in an extensive statistical analysis by New Zealand EV user collective “Flip the Fleet” from March 2018. These findings confirmed the experience of many LEAF drivers, who had seen the maximum range of their cars rapidly decline and were met with disbelief by Nissan.

Yikes.

To say that the Nissan response has been lackluster is way too friendly. It has taken three years for Nissan to acknowledge that the problem existed and come with an explanation and solution. The explanation is that the software computing the charge of the battery contained a bug, reporting less capacity than there really was (resulting in less range) and reporting a depleted battery before it was empty.

Nissan does not have over-the-air updates like Tesla. That means you have to visit a Nissan dealer to get the patch applied. After the software upgrade, the 30kWh battery is as good as its 24kWh sister, as good as you can expect of a battery without a TMS.

The battery capacity is automagically restored to the level it really has and the range calculation is better than it was.

These LEAF batteries are adequate for temperate zones like Western Europe, Japan, and some parts of the USA, like New England, but they are not fit for regions with extreme heat or cold and the lack of a TMS makes road trips with repeated fast charging hard to do in any climate. The only way is leisurely wandering from charger to charger. Perfect for some types of holidays, but when you want to reach a destination, let alone a cannonball run from coast to coast, this is not the battery you want.

The long overdue new battery from LG Chem is supposed to have a TMS. But the waiting time for that larger battery keeps increasing. Now that the sale of AESC to a Chinese investor has been canceled and NEC is replaced by Envision as a partner in AESC, with Nissan keeping a 25% stake, we can expect AESC to stay on as the battery supplier for the Nissan LEAF and future Nissan electric vehicles. Knowing what we know now about batteries, it is time for AESC to develop a battery with a good thermal management system.

My advice would be to buy that technology (and equipment) from Tesla. They make the best and lowest cost batteries in the world. 
 





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About the Author

Grumpy old man. The best thing I did with my life was raising two kids. Only finished primary education, but when you don’t go to school, you have lots of time to read. I switched from accounting to software development and ended my career as system integrator and architect. My 2007 boss got two electric Lotus Elise cars to show policymakers the future direction of energy and transportation. And I have been looking to replace my diesel cars with electric vehicles ever since. And putting my money where my mouth is, I have bought Tesla shares. Intend to keep them until I can trade them for a Tesla car.



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