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GM, BMW, Toyota: More Work to do on Batteries

A few days after GM magnanimously offered to give loaner cars to any Volt driver who might experience post-crash burning battery problems, BMW and Toyota announced that they would work together to develop lithium ion batteries for hybrids and all-electric cars.

This is what BMW’s Klaus Draeger had to say about why it was neccesary for the two auto giants to join forces:

Battery technology is crucial for the future of hybrid technology  – but also for the future of individual mobility. Whoever has  the best batteries in terms of function, cost, and quality in their  vehicles will win more customers. We want to set benchmarks in the  future with both: hybrid and electric cars.

It clearly makes sense for experienced and innovative companies to  pool their expertise and power with such future-orientated  technologies. Toyota and the BMW Group are perfect partners: Toyota is  the most sustainable and experienced producer in the high-volume  segment. And Japan, of course, is the country that has made hybrid  cars well known around the globe.

BMW will help out Toyota by supplying it with what it calls clean diesel engines that the Japanese firm can use to improve the cars it would like to sell in Europe, where diesel engines are preferred. Draeger characterized the battery partnership as involving basic research. Generally speaking, things like range and charging times are the main targets for research but…

BMW's all electric i3 concept car. Credit: BMW

GM’s experience with the Volt suggests that safety issues are still in play. Lithium ion batteries can reach high (flammable) temperatures if the separator material between the anode and cathode is breached, causing a short in the battery. That is why the problem with the Volt seems to happen in cars after impact  (crashed on purpose for safety testing) – presumably something compromised the separator in the battery.

Lithium ion car batteries come in different designs. Interestingly, no similar problems have yet been reported for the all-electric Nissan Leaf. Still, they commonly feature many individual battery cells that are grouped together and surrounded by an active management system that is supposed to prevent runaway reactions that would lead to fire. I suspect that these systems are still a p0int of design weakness. Even if they work pretty well, it seems a more competitive design for a lithium ion car battery would be one that does not require an additional surrounding system to prevent disaster.  (Some would call this “inherently safer design”)

To read more about the safety testing that revealed the Volt’s possible fire issues, check out the coverage in the New York Times.


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