No Active Thermal Management: Did Nissan Make the Right Call?

· · 11 years ago

After 14 months and 37,000 miles of driving my MINI-E, there is really only one glaring flaw that I can find with the car (besides only two seats that is): The lack of a sophisticated thermal management system.

As much as I love the car, and I really do love it, the passive air-cooling battery system is woefully inadequate for the hot summer days, as well as the cold New Jersey winters.

I'm not complaining. The MINI-E is is a prototype test mule—a car that was designed for an internal combustion engine and was retrofitted with a 35 kWh battery pack and an electric drivetrain. I knew there would be occasional problems and that the car wasn't really "production ready" when I agreed to be in the trial lease program. That said, the car has performed admirably and only needed to have two of its 48 battery modules replaced so far. I knew the lack of a thermal management system would affect the car's performance, and I accepted the possible inconveniences so I could have the opportunity to drive an electric car for a couple years.

Ready for Prime Time?

On the other hand, I'm not so sure Nissan LEAF customers will be as forgiving if the car falls short of expectations in extreme temperatures. Buying a $32,000 car is much different than agreeing to be part of a beta test for one or two years. Nissan has been defending its decision to sell the LEAF with basically the same temperature management system the MINI-E has—fans that blow cabin air across the pack to cool or warm it.

I really hope they have made the right decision. I really am pulling for the LEAF. I want to believe it's ready for prime time. I am hoping that the combination of better battery chemistry and the ability to warm or cool the cabin (and thus the batteries) while the car is still connected to the grid (the MINI-E cannot do this) will allow for better performance than I see with the MINI-E.

When I was at the New York Auto show this year, I grilled the Nissan representatives about this—so much so they really just wanted me to leave. Although they were steadfast in saying, "We are confident the LEAF will perform well in all ambient temperatures," I did get one person to concede that they are working on an active thermal management system and could possibly be an option for the Generation 2 LEAF for regions that are particularly hot or cold. Ah, so they are a little worried.

Warranty In Place

Recently, the CEO of Tesla said the LEAF's battery is "primitive." Strong words from someone that really isn't in competition with Nissan just yet. However, it did put the spotlight on Nissan and I think they need to make some kind of statement as to why we can feel confident that the car isn't under-engineered. The 8 year / 100,000 mile warranty is a good step in the right direction and shows confidence, but I think Nissan needs to be a little more forthcoming about why they decided to omit what just about every other auto manufacturer believes is necessary in an EV.

I have recorded battery temperatures as high as 119 degrees on my MINI-E and performance really suffers when the temperature gets above 105. In fact, the car refused to charge a few weeks ago because the batteries were too hot. Additionally in the winter, the range gets reduced by about 25% when the temperatures drop below 40 degrees. I have even had a few extreme instances on really cold days where the range was reduced by as much as 40%. Again, all this is acceptable for a prototype test car, but how will people react if this happens with the LEAF?

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