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Nissan Leaf Quick Charge vs. L2 Charge Study

Discussion in 'Technical' started by techmaven, Mar 19, 2014.

  1. techmaven

    techmaven Active Member

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    #1 techmaven, Mar 19, 2014
    Last edited: Mar 19, 2014
    Apparently the Idaho National Laboratory (INL) has been conducting an experiment with two pairs of Nissan Leafs to compare battery degradation with charging off L2 versus charging with Quick Charging:

    QUICK CHARGE = QUICK DEGRADATION? | Simanaitis Says

    There is a marked effect on using quick charging on Nissan Leafs. Further, the batteries themselves have degraded significantly at 40k miles (over 20%). These cars are tested under a pretty significant duty load - about 140 miles a day with two near full charge cycles. What's even more disturbing is the slope of the degradation. The Panasonic paper on NCA degradation showed a slope that was steep and first and then leveled out. The INL study on the Leaf has an accelerating degradation.

    Paper by Panasonic on restricting DoD for longer cycle life, look at the 2nd graph:
    Development of High Power and Long Life Lithium Secondary Batteries


    Still though, it points to the fact that Nissan's choice of using an air cooled battery pack with lithium manganese chemistry was pretty short sighted.
     
  2. ReddyLeaf

    ReddyLeaf Member

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    A couple of threads on this topic over at MyNissanLeaf.com:
    My Nissan Leaf Forum View topic - INL L2 vs DC initial capacity test results after 50k mi+
    My Nissan Leaf Forum View topic - 2013 LEAF AVTA testing

    While I won't dispute the Leaf's battery degradation at higher temperature, I will say that the Leaf performs well for it's likely intended use: short (<40 mi), in-town trips at moderate temperature. Outside of that range, it struggles due to it's lack of thermal control and smaller battery.

    The Leaf is seeing significantly greater DOD and cycling than the Tesla due to it's 75-85 mi EPA rating (2011-2013 models). I haven't done any detailed calcs, but I would be surprised if the Leaf DIDN'T have 20% degradation under those conditions. Data I've seen suggests ~2000 cycles for LiIon batteries (yes, all over the place depending on chemistry and DOD). For the Leaf, that's around 150 Kmi. Best case for the Leaf is TaylorSFGuy in Seattle who should now be approaching 120 Kmi and is around 75% battery. In contrast, 2000 cycles in the Tesla should occur around 600 Kmi (we'll have to wait a while for that one), hence the reason for Tesla's unlimited mileage warranty on the battery.

    There is no question that the Tesla is a higher end product with more distance capability than any other EV on the market. I always tell people to use the product that makes the most sense for their specific needs. If you drive 150 mi/day, then get the Tesla. If it's only 30 mi/day, then the Leaf (or Volt, FFE, etc) will work just fine. My needs don't justify a Tesla (as much as I've tried), though I may reconsider a used X when my Leaf reaches 150 Kmi (probably in 2025).
     
  3. renim

    renim Member

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    No
    it suggests the targets Nissan set for battery pack were not adequate for southern US consumers.

    or to state it another way

    improved electrolyte purity / additional electrolyte additives / finer NCA blending / tougher Manganese Spinel dopants

    could, with skill, make an ambiently cooled battery pack with lithium manganese chemistry with better longevity than its below ambient, cooled commodity NCA equivalent.
     
  4. David99

    David99 Active Member

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    Exactly! I really wanted to get a Leaf or a BMW i3. But I realized for my driving needs neither would work. I tried every possible scenario to make it work, but it didn't. The Tesla fits my needs so I went with it despite the high price. If I had a different job with a normal commute, the Leaf or a similar EV would be my car for sure.
     
  5. ReddyLeaf

    ReddyLeaf Member

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    ^ Agreed! My experience in LA was a 3-4hr drive across it to Malibu at 2 am. I can easily see needing 200+ miles of range in LA. Up here, it's less than 20 mi across our metroplex and my commute is 8 mi (which I mostly bicycle in the summer).
     

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