Liquid-cooling may add complexity to battery packs. Even so, it is the best option under all weather conditions: it allows for more precise and effective temperature control in the most expensive component for electric cars. The Nissan Leaf and the Renault ZOE opted for air-cooling for cost reasons and the video above shows why that may be more expensive in the long term – for customers, mind you.
James, from the James & Kate YouTube channel, is one of the technicians at Cleevely Motors Ltd., a British garage that is specialized in EV repairs. In this video, he and his colleague Matt repaired a 2018 40 kWh Nissan Leaf with a little less than 120,000 miles on the clock. Working as a taxi, it is charged four times a day.
The EV came to James and Matt with range issues. A brief inspection revealed one of its modules was failing to balance. When the technicians took out the battery pack, they saw that the rear module stack was expanded.
As James explains, that happened because the rear module stack is the one that gets the hottest. If it has constant fast charging and heavy use such as this Leaf has experienced, that can lead to the expansion this video reveals.
Some commenters in the video said James and Matt should have replaced all the modules that are expanded but this was not what they decided to under the request of the car owner. Whatever was working should stay in the car and the technicians just replaced the defective module. The fully operational ones remained in place.
The repair process shows that people with the right knowledge can probably keep these Leafs running for quite some time. James and Matt checked all the modules, found the defective one, replaced it, put everything back together – with a ratchet strap because of the expansion – and reinstalled the battery pack in the car. It all cost £900, according to James – way less than Nissan charges for its battery packs.
It is a fact that this Leaf had more in these three years and 120,000 miles of use than most EVs may see in a lifetime. Despite that, the battery pack of a car with liquid-cooling submitted to the same challenges would very likely be in much better shape if its battery management system worked as intended. It is not by chance that Nissan abandoned air-cooling and CHAdeMO for the Ariya. Remember that when buying your EV.