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Battery impact of very low power charging

Discussion in 'Model S: Battery & Charging' started by kiwi, Jul 21, 2018.

  1. kiwi

    kiwi Member

    Joined:
    Oct 1, 2017
    Messages:
    62
    Location:
    New Zealand
    There has been lots of discussion and research on the impact of very regular supercharging on battery life.
    It appears the answer is “not much”.

    I’ve moved out of my house for a few weeks (renovations) and am living at the beach, 1.5-2 hours away from work (long windy drive... but totally worth it!). I commute 2-3 days and work from home the rest. I only have 10A/240V charging via the UMC and a regular wall plug here, resulting in a rate of 8km/hour (I’ve been waiting on my referral HPWC for 10 months now).

    Basically the car is charging *all the time* to keep up. It takes nearly 2 days to get a full charge for 1 trip in and back. If I go in for 3 days of the week, my car is charging roughly 130 of 168 hours per week.

    I remember reading a battery researcher who mentioned that its better to reduce the amount of time L-Ion batteries spend undergoing chemical changes (charging) and so charging faster is better. Does anyone know of research or data on the impact of long term, very slow charging?

    Thanks
     
  2. Rocky_H

    Rocky_H Active Member

    Joined:
    Feb 19, 2015
    Messages:
    2,472
    Location:
    Boise, ID
    I do also remember seeing a paper with graphs on that a couple of years ago and seeing that same thing, where it has that bimodal effect: very fast charging is stressful on the cells, and very very slow charging has them in that charging state for really long periods of time, which is also a little harmful. I did try to look for one of those reports about it a week or so ago, but it's hard to find. Most people don't care about recharging batteries as slow as possible, so most of the studies don't look at that effect much.

    I think it's a less problematic effect than too fast charging, and 2.4kW is pretty decent--at least you're on 240V. You're just driving a lot of miles, and so you do what you need to do. At least this is something you're going to be able to change sometime in the next year or so, so it's not like a daily 10 to 15 year effect. I would just be glad you do have reliable home charging, and you're getting to rack up a lot of miles on electricity.
     
  3. mtndrew1

    mtndrew1 Member

    Joined:
    May 12, 2015
    Messages:
    436
    Location:
    Gardena, CA
    I think you’re referring to the presentation by Jeff Dahn at Dalhousie.

    I don’t have time to watch his presentation again (which was excellent) but if memory serves the primary impact came from long charging durations while at very high cell temperatures. This famously impacted the Nissan Leaf quite dramatically with premature degradation as it has no cooling.

    Given the Tesla has a sophisticated thermal regulation system I really wouldn’t give it a second thought if I were you.
     
  4. kiwi

    kiwi Member

    Joined:
    Oct 1, 2017
    Messages:
    62
    Location:
    New Zealand
    Hey @Rocky_H, @mtndrew1
    Thanks for the feedback.
    It is temporary, so its not going to matter I'm guessing.
    Talked to the local tesla service people for their opinion, and their
    line is that heat is the enemy, and slow charging will not build up any heat.

    I think that lines up with both of your comments.

    It sure does complicate charging - we have to make sure we arrive home with enough
    juice so that remaining juice + overnight charge gets us back into the city.

    Having said that... I'm driving an MX and living at the beach. Can't complain :)
     
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