Tuesday, July 22, 2014

How Big Is My Battery?

I am a day away from 10,000 miles on my LEAF and so far, it has exceeded my expectations by a good sum. The extra 7-10ish miles of range I have has really made a difference in the car's usability. But like all good things, it will not last. Degradation will happen and I might be seeing the first signs of it now.  The past 2 days in a row, I have had the full 284 GIDs but only seeing 22.0 Kwh available. This is a drop from the 22.7 kwh I was seeing before.  Now as a refresher, my highs from LEAF Spy.  Other monitoring devices might be slightly different

GIDs;  284   (up from 281 on the 2011/12's)_

Kwh available; 22.7  This number widely reported from other users as well

Ahr;   67.36  Again, widely reported by others.

SOH; 106.65%  This number has the greatest variance from other LEAFers. I have seen reports as high as the 109's.  I did see a reading of 107.10% on my LEAF once but I only record readings first thing in the morning so I will stick with that.

Ok, so a GID was thought to be 80 watt hours more or less. The values do seem to change at different SOC's although I suspect its partly accuracy issues with Nissan instrumentation along with the irregularities associated with measuring electrical charges in general.  So 300 GIDs would make a 24,000 watt hour battery right?  So the LEAF leaves roughly 16 GID or about 1280 watt hours unaccessible at the top end which means that all of the battery at the bottom end is accessible??

Well, of course that cannot be true, right?  After all, its generally accepted that the deeper the discharge, the worst it is for the battery.  So we have Turtle mode that warns us when we are getting to the danger point.

Ok, so yesterday, I drove 89.3 miles and due to the late hour returning home, I was driving much faster than I normally would be but monitoring my progress with LEAF Spy to insure I did not speed my way into a tow.  The last 20ish miles (traffic does not permit me to drive faster sooner even at 8 PM!)  was done at 70+ MPH and I realized something.

Despite having exceeded 95+ miles over a dozen times, I have never really come close to turtle. The other day, I drove 99.3 miles and still had 12 miles left on GOM (traffic was HORRIFIC) In fact, I just realized that besides not getting close to turtle, I have just barely hit VLB territory.

I had been under the impression that my "22.7 Kwh available" was not all available and that some of that at the lower end would be in turtle mode. Well, yesterday, I went all the way to .7 kwh and no turtle.  I then went to grab food and come home, down to .4 kwh and still no turtle.

I mean, what is the deal here? Nissan are you seriously allowing us to go to ZERO percent SOC? or is the instrumentation that far off, or...

Did you give me a bit extra and decided to not mention it?

I guess, the one thing that is possible is that my "22.0" available was actually still 22.7 and the BMS is making adjustments due to heat. It has been a lot hotter here (just now cooling off the past two days but at night only) and yesterday was a full Sun day so the car was VERY warm...

Either way, I hesitate to make any claims on capacity, degradation or longevity. With the readings I am getting, I simply can only say;

I will keep you posted!


  1. I assume that zero state of charge just means that the battery is as discharged as Nissan chose to allow, not that the battery has supplied all the energy that it is capable of. Lithium ion and related chemistries will supply some energy all the way down to zero volts, but will likely be destroyed in the process. Nissan had to define a "zero" point that wasn't too harmful to the battery.

    1. Well the 16 GID at the top that that we cannot access is 1280 watt hours or 1.28 kwh if a GID is 80 watt hours. Some think its more like 78 watt hours but even that would only be 1248 watt hours leaving 22.752 kwh left. if the 22.7 kwh is accurate then that leaves only .052 kwh as un accessible at the bottom? that seems too low to me!

  2. I have driven my 2014 to turtle on purpose. And here is what I found: Kwh stops for a long time on 0,5kwh left.. So you actually use much more then the remaining 0,5 kwh to get to turtle.

    The turtle finally said hello, but not before SOC was about 1,8%. Kwh starts to go down a bit in the end, after freezing for awhile at 0,5kwh ( can't recall how low it goes but I think something like 0,3 kwh). Lowest battery voltage was about 3.0.
    GID and SOC sync in the end at the mentioned 1,8 %.

    On my old 2011, turtle mode started from about 5% SOC and also 0,5kwh left but there was no delay when you got to 0,5kwh. Lowest cell voltage was 2,5.

    Some thoughts: Seems like the new battery has a much higher cell voltage at turtle mode. 3 volts is not that low so maybe it's not so hard on the battery to drive to turtle, compared to the old model?

    Could also mention that my car is showing as low as 60 ahr now compared to 66 when I got it a few months ago. I don't really care as I think the range is excellent (compared to my old Leaf). Also I think the number is wrong. It have not gone up much after quick charging, as you have suggested. I have a theory that it is in some kind of protection mode after a long road trip I had. Got all temp bars showing not including the red ones.

    Great blog! Keep it up.

    1. Thanks for the feedback! I have seen others reporting ahr in the 60 area as well. interesting yours happened right after a long trip with high TBs. Check back this fall after the weather cools. interested to see where you are at. As far as living or dying over numbers; you are likely correct in that your numbers are not a true reflection of your battery pack's status. mine bounces from the mid 63's to the high 66's. that is a pretty wide swing! as far as hot goes; never beyond 6 bars so far.