Battery Low Down

Posted in: Comment, News and Updates

When we bought our electric car in 2014, no one explained that it wouldn't be able to go as far as promised in Winter or when it was cold in Spring or Autumn.  Being charitable, I'm assuming that the retailer did not know about this.  They do now, of course, and it's a real problem when it's very cold – as opposed to the south of England where the cold is only really of the pretend sort.

An article in The Conversation by Assistant Professor of Mechanical Engineering and Mechanics at Drexel University, explores this phenomenon by looking at low temperature battery chemistry.  This is his key point:

"Batteries contain fluids called electrolytes, and cold temperatures cause fluids to flow more slowly. So, the electrolytes in batteries slow and thicken in the cold, causing the lithium ions inside to move slower. This slowdown can prevent the lithium ions from properly inserting into the electrodes. Instead, they may deposit on the electrode surface and form lithium metal."

He also notes:

"If too much lithium deposits on the electrode’s surface during charging, it may cause an internal short circuit. This process can start a battery fire."

I've learned to live with a chilly battery and mercifully, it's never caught fire.  Naive chemist as I now am, I had assumed that the changing process would increase the temperature of the battery and so counter the outside temperature.  Ten Winters on, I no longer hope for this.

Ours is a small electric car which cannot go far.  We only ever charge it at home but range anxiety is never far away.  Indeed, even when the battery is full we're very conscious of the range which varies by 10-15% between Winter and Summer.  But it really is ideal for local travel and has been trouble-free apart from replacing an air bag sensor.  On the highest regenerative braking level it's possible to drive around without using the brakes very much (the brake pads are still the original ones).  But now, 10 years on, I read that this is not a good idea as range is better at a low-level of regeneration.  Who knew?

We're sticking with our small BEV and still resisting buying a big one for all the reasons that are well rehearsed.  Now the government is under pressure to relax its market distorting rules forcing manufacturers to sell a rising proportion of EVs every year.  I sense another NetZero U-turn coming up.

Posted in: Comment, News and Updates


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  • I often wonder whether putting more emphasis on Systems Thinking (also known as Complex Systems Science) might help bureaucrats, politicians and gung-ho environmental advocates (I could list a whole spectrum of groups) understand the bigger picture of what they claim are policies that will help the world thrive.

    Individual problems are easier to solve and hence complex problems are too often conveniently reduced to simpler problems to make it look as if simpler proposed solutions are what is needed.

  • Always good to hear a realistic point of view to policies that politicians want to ram through in order to make them look like they are doing something about a problem. After all that's what we expect politicians to do. It would be better if those politicians could think systemically and hear alternate voices that temper their enthusiasm to justify their positions over doing the right thing.