managing without tms

Discussion in 'LEAF' started by Paul K, Jun 1, 2018.

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  1. Paul K

    Paul K Active Member

    Nissan has taken a lot of heat (pardon me) over the lack of TMS in the battery packs. There are definitley some situations where this will be a major problem but others where it won't. I've started paying a lot more attention to my temperature bars as a result of the negative commentary and this is what I've found thus far. BTW my car is a 2016 SL with a 30kwh pack. Still have all the SOH bars at 32,000K but think I may have lost about 3% range since new.

    The heat does take some time to get out of the pack. I sometimes even gain a temperature bar after parking which indicates that without the air movement under the car the residual heat generated by usage is trapped like when you first turn off an ICE the coolant temp can go way up. It seems to take several hours for the bars to drop down to where they were at the start of the day. I imagine it would be worse having to park over hot ashphalt.

    With the summer temps here I usually find myself starting out with 5 bars and add a bar with highway use. On May 30, 2018 which reached 30degC here I did a run in which I was able to use a DCFC. It raised the temp bars from 6 to 7. It did not drop back to 6 bars all the way home (about 70km). A previous fast charge last year raised me from 4 bars to 5. So I can see where a long trip with multiple fast charges is going to make trouble.

    Another finding: SPEED KILLS! It's a real range killer. A recent run at 120km/hr showed I was getting only 4.6km per kwh. Second part of trip was on the two laners between 80 & 90km/rd and I got 6.7km/kwh. On my May 30th run I got between 7 and 7.5km/kwh which was really quite exceptional. Tooling around town I get as much as 9km/kwh.

    Higher speed driving (which the Leaf does beautifully) will heat the battery up more as heat produced goes up as the square of the current drawn and also means that much more charging and discharging takes place for a given amount of km driven. So a Leaf that's driven 5 days a week on a freeway commute should experience more degradation than one mostly used around town for the same amount of KM.

    So, for someone contemplating a Leaf purchase I offer these scenarios for your guidance:

    EXCELLENT: You're a 2 car household and use a gasser for longer trips and the Leaf for all your local gofer trips. Better love that Leaf. You're going to have it a long time.

    EXCELLENT: Your Leaf is used mostly urban/suburban with some highway trips but you keep your speed down, use climate control sparingly and only DCFC when you have to. This is my situation.

    GOOD: You have a commute with a short freeway sprint but can do the round trip on a single charge. You L2 charge at mostly at home.

    FAIR: Your commute is just a little past range so you top up at work or on along the way with an L2.

    POOR: Your commute requires a full charge at both ends. All this charging will shorten the life of the pack.

    BAD: You live in an area with lots of summer heat. You've got a lead foot and drive 75mph on the freeway with the a/c on. You want to drive the same way on longer trips topping up with DCFCs. The Leaf will probably end up being a disaster for you.

    I would love to see comments from other Leaf owners about their experiences.
    Domenick likes this.
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  3. Kenneth Bokor

    Kenneth Bokor Active Member

    Hi Paul, great write up and I totally agree. I have a new 2018 Leaf and I fall under the Excellent findings (both) as we have 3 vehicles, with 2 being ICE and the main one being the Leaf.

    One item I want to point out is that the Leaf can do even the Poor or Bad situations you describe. Longer trips with heat build up will just lengthen DCFCing successive sessions without any overnight or stops for longer cool-downs. Nissan claims that this throttling-down for DCFCing along with the battery chemistry change should lengthen pack life and slow down degradation. Not eliminate it completely of course.

    So far, I've only had to DCFC once and only for 20 mins as I just needed a bit more juice to make it back home after a longer trip. Current summer range with 25-35 degrees C temps I am seeing 260-300km starting ranges after full home charge. Perfectly capable for the majority of use cases.
  4. Paul K

    Paul K Active Member

    Not sure I'm doing this right. Time for a little update on this post. I had a 30kwh 2016 Leaf at the time. In 2018 bought a new "S" with the 40kwh pack. This combined with the emerging public charging facilities means that I can now go on much longer runs without needing the old ICE vehicle. One particularly long run involved 3 stops for DCFC top ups.
    For all the noise that has been made about battery overheating, I only got up to 7 bars after the 3rd DCFC. Now temperatures were slightly below freezing at the time and I actually enjoyed a small range increase as a result of the higher battery temp. It will be interesting to try this in summer temps.
  5. Kenneth Bokor

    Kenneth Bokor Active Member

    Hi again Paul, I totally agree and the Leaf is a very capable BEV, even without ATM. I did have the BMS update done later last year and that made an improvement in multi-fast charging over a single day.

    For the vast majority of the millions of potential EV buyers out there, the Leaf offers a great BEV solution.

    I just did a brief 21-month review (along with a talk with Nissan Canada) on one of my recent YouTube Shows. You can check it out here:


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