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posted by Fnord666 on Thursday May 16 2019, @04:11PM   Printer-friendly
from the your-mileage-may-vary dept.

Autoweek (and other car news outlets) summarize some independent testing: https://autoweek.com/article/green-cars/how-much-does-cold-weather-cut-electric-vehicle-range-quite-bit-aaa-study-finds

AAA partnered with the Automotive Club of Southern California's Automotive Research Center for its tests, which allowed it to run drive-simulating dynamometer tests in 20-, 75- and 95-degree Fahrenheit temperatures in a controlled laboratory setting. This is way more scientific than anything we'd be able to achieve toodling around in an EV in Detroit the next time a polar vortex hits.

A handful of key points pulled from the report:

- The increased use of HVAC systems in extreme temperatures has a bigger impact on EV range than decreases in battery pack efficiency caused by the temperatures themselves.

- Moreover, while both extremely hot and extremely cold temperatures affect range, you'll incur a significantly larger penalty when heating up a cabin than you will cooling one down. Compare that 41 percent decrease at 20 F to a mere 17 percent decrease at 95 F.

- The BMW i3s saw the biggest reductions in range in both hot and cold conditions, losing 50 and 21 percent of range in cold and hot conditions, respectively.

- The Nissan Leaf was the most versatile, losing 31 and 11 percent of range in cold and hot conditions, respectively.

The other test cars, Tesla S, eGolf and Chevy Bolt fell between these extremes. The article includes a link (pdf) to the original report with many more details. Worth reading if you live outside southern CA and are considering an electric car.

This AC is considering an electric car, and I'm fortunate enough to have an attached garage to keep it warm-ish, probably above freezing, even if the outside temp gets down to 0F (-18C) which is a typical low for my location. That means that any trip will start with a cool (not cold) battery & cabin...but after parking outdoors at my destination(s), I'll have a reduced range for the trip home.


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  • (Score: 2) by KilroySmith on Thursday May 16 2019, @05:08PM (6 children)

    by KilroySmith (2113) on Thursday May 16 2019, @05:08PM (#844347)

    >>> Do I have to replace them after 8 years?
    Batteries don't generally fail (although it can happen, much like an engine failure in an ICE), what happens is that over time their capacity reduces. In the Tesla world, it's expected that the batteries will still be at 90+% capacity after 200,000 miles (300,000 km). See:
    https://electrek.co/2018/04/14/tesla-battery-degradation-data/ [electrek.co]

    I love my Tesla Model 3.

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  • (Score: 2) by Snow on Thursday May 16 2019, @06:42PM (3 children)

    by Snow (1601) on Thursday May 16 2019, @06:42PM (#844398) Journal

    it's expected that the batteries will still be at 90+% capacity after 200,000 miles (300,000 km).

    I'd feel more comfortable to see the actual results. There will also be more (hopefully cheaper and better) selection then too.

    • (Score: 2) by KilroySmith on Thursday May 16 2019, @06:46PM (2 children)

      by KilroySmith (2113) on Thursday May 16 2019, @06:46PM (#844401)

      >>> to see the actual results
      Well, if you had followed the link I so helpfully provided, you'll see that the data is from real-world usage, with a smattering of data going up to 250,000 km. Is that close enough for you?

      It also has data for an EV that doesn't have a temperature-controlled battery - which shows why keeping the battery happy is a good thing.

      • (Score: 2) by Snow on Thursday May 16 2019, @07:02PM (1 child)

        by Snow (1601) on Thursday May 16 2019, @07:02PM (#844413) Journal

        The sample size in the provided link is small with sparse datapoints beyond 150K kms. I'd also like to have more confidence in how the batteries hold up with Canadian winters and the constant freeze/thaw that happens here.

        If I'm going to drop $40k, I want to know it's going to work as advertised.

        However, I'm glad there are people like you that take the plunge. Someone has to lead the pack.

        • (Score: 0) by Anonymous Coward on Thursday May 23 2019, @09:05PM

          by Anonymous Coward on Thursday May 23 2019, @09:05PM (#846795)

          There's lots of good data for the chemistries being sold right now. Basically if you don't charge or discharge below 2-3 Celsius, you can expect cell life to match the published capacity drops for charge cycles. Panasonic and others publish their cell specs*, which do vary by cell chemistry and so you have to match to the pack in the vehicle you're considering.

          Freeze/thaw cycles have minimal performance on most lithium chemistry cells, so long as they're not charged/discharged while freezing but you're Canadian, you're probably used to engine warmers (and therefore, amusingly, non-electric cars with electric plugs dangling out the front).

          *they have to so that engineers can plan devices around the capacities and performance windows of the cells!

  • (Score: 2) by bob_super on Thursday May 16 2019, @08:28PM (1 child)

    by bob_super (1357) on Thursday May 16 2019, @08:28PM (#844450)

    > Batteries don't generally fail (although it can happen, much like an engine failure in an ICE), what happens is that over time their capacity reduces.

    I read that you reach a cliff effect, sometimes around 40-60%, where the most degraded modules can just short and cause the rest to not work anymore.
    That problem could be solved by having the manufacturers make the batteries modular enough that someone could change/remove the worst ones and keep driving on the remaining less-degraded ones, but we're not there yet. Right now you have to change the whole battery, which does give you essentially a new car.

    The whole repair-rather-than-replace will probably come, as usual for these kinds of things, in another decade, through a mandate of the EU.

    • (Score: 3, Informative) by Luke on Friday May 17 2019, @04:36AM

      by Luke (175) on Friday May 17 2019, @04:36AM (#844600)

      The Nissan Leaf battery is modularised and you can replace individual cells.

      You can even replace lower capacity batteries with larger units (eg put 24kW -> 30kW).

      These guys: http://evsenhanced.com [evsenhanced.com] know all about it, and have equipment available to assist with battery swaps etc.