E Pedal!! Or, maybe B ECO!!..or maybe D?

 There seems to be a growing resentment from the LEAF community from new drivers slowly realizing that E Pedal is not very efficient.  Its not hard to understand how they got that impression since E Pedal is capable of regen levels more than 50% higher than B mode. More regen means more range recovered, right? But that is a two sided street and you won't like the view.   So why do we have E Pedal and what is the best mode to drive in for best range?   To answer that, we have to clarify several different mitigating factors and even after addressing those factors, the key takeaway will continue to be YMMV. 

E Pedal

E Pedal was added to the Gen two LEAF when launched in 2018. It enables one foot driving where you could conceivably drive all day without moving your foot from the accelerator only touching the brake pedal to start the car.  E Pedal does this by a combination of increased regen approaching 60 kW and friction braking which can bring your LEAF from 40 mph to a complete stop in less than a block.  The amount of friction braking varies by SOC and speed. At street level speeds, friction braking kicks in at very low speeds only so its mostly regen slowing you down.  The only exception to the rule is when the SOC is high enough that regen is limited.  Friction braking increases at high SOC to make the "drive feel" consistent.  If you had an older LEAF (or a new one) fully charged, you know that the car seems to move a lot faster until some of that charge is used up. This is due to little/no regen and the considerable difference in how the car drives can be a bit disconcerting to some. 

B/D

D mode is probably the closest "drive feel" to a normal gasser. Car is responsive, only slows a bit when foot is removed from the accelerator, etc.  It has the lowest level of regen which means you maintain your speed longer. At 40 mph, it will take you just over 2 blocks to slow down to "idle" speed. 

B mode can be looked at as "2nd gear" in a gasser. Regen is stronger and you will feel a "sluggishness" (which isn't really possible in an EV BTW...) or heaviness when driving. B mode will take you to idle speed in just over a block. 

In both D and B, you must engage E Pedal or friction braking to come to a full stop. 

Efficiency

EVERYONE has an idea of what efficiency means and how to achieve it but only a handful do so why is that?  First off, regen is NOT your friend. 

Regen is like that credit card in your pocket. It is very handy and convenient when you need it but as we all know, too much reliance on credit will get you in trouble. Regen is the same. Yes it puts some of that charge back into the battery but at the expense of velocity; velocity that will use more energy than regened to recover. IOW, its a no win scenario. The house always wins and that is due to gravity. Gravity takes from the charge coming from the battery and takes from regen going to the battery. Of course, manual friction braking should never be used unless absolutely necessary. 

Now that we know what not to do, what do we do? Maintain velocity!  After all you didn't get your car to park, you got it to go, so whatever it takes to go is your goal. 

Negotiating Traffic

Above we talked about the different drive modes and how quickly they can slow you down. ALL of them would be just fine (actually not totally true and we will get to that) if you were the only car on the road. Well, that isn't going to happen so our efficiency goals are challenging in that constant changes in traffic conditions means constantly reevaluating the best drive mode. 

When I brought my 2018 home in February 2018, I was an E Pedal fanatic. It was awesome especially in the stop and go traffic I dealt with daily on I-5 but soon quickly realized that the high regen made driving efficiently difficult without a very high level of concentration to my driving.  At the time when I was doing daily phone conferences for work, etc. that was simply too hard for me to do.  It was then that I decided to make a goal of driving an entire month w/o touching the brake pedal. The only real way to do that was manipulating regen to match the flow of traffic. I haven't accomplished that goal yet and July 2022 is out of the running but I did make it to the 20th one month so I am confident it will happen! 

Anticipation

Expanding my "empty road" comment.  Even without traffic controls or traffic, drive mode still matters and the biggest reason is its difficult to maintain a steady flow of power without actually thinking about it. Now, we all know its easy to do for a bit because we have all done it.  But try doing that for an hour or even 10 minutes. Its tough!  So for most of my driving, I am in D mode (ECO is ALWAYS on simply because there is no good reason to turn it off) because its the lowest level of regen and so those tiny slips of the foot means just a small regen hit instead of the very large one E Pedal provides. 

Cruise Control

Cruise control is a way of maintaining pace with traffic. You can bump your speed up or down in one mph increments as needed. So its a convenience thing but its not very efficient.  When the car slows due to small slopes in the road, the car will slow ever so slightly until it gets below its setpoint then overly accelerate to return to the set speed. IOW, its not very smooth. Unlike ourselves who can feel very small changes in velocity and increase power slightly to compensate, the car cannot. ACC is the same times 10. 

Now, I have used CC a few times especially when I was in the middle of something like a call or whatever during very light traffic but I tend to avoid it for the most part. I live in an area where traffic flow is not consistent aggravated by complete disregard for the "stay right except to pass" law.  So its a constant changing of speeds. 

Scenarios

Remember the final takeaway YMMV and that applies to everything here.  This includes what I am about to explain because I can only give you my experiences based on my local driving conditions which will be different than yours. 

A typical drive on the streets, I am doing 40 mph, I see the light 4 blocks ahead turn red, I know its weight controlled and there will be about 6-10 cars in front of me so what do I do?

I immediately shift to N because it maintains the most speed and requires least amount of work so yeah, I am lazy but in random uncontrolled observations, it also seems to get me higher numbers so...  Two blocks away, light turns green. I remain in N now going 35 mph. My hope is that the traffic will clear the light and I will pass thru the light at 25-30 mph using no regen at all shifting back to D.  During this time, my surrounding aura is happy, everyone is happy.  Life is good. 

Same scenario above but this time its a major intersection during a busy time of the day which means a longer light cycle which means no chance of maintaining most of my velocity. Light turns red, I am 4 blocks away, I immediately reduce acceleration to maybe one bar slowing to 25 mph then shift to N.  Aura is crashing! People around me are in a championship race to see who wins the "I spent the most time stationary at a stoplight" contest. Cars start zipping around me only to slam on their brakes to stop behind a line of cars still sitting at the red light.  I now have just under a block to go to get in line at the light and it turns green, I shift back to D or sometimes B if the line of cars is long enough but eventually ending up in D. My goal is to have the intersection clear as I roll up at very low speeds generally under 10 MPH but that only happens about half the time so E Pedal is engaged if a full stop is required. Aura starts to climb. My fellow drivers are piling up stationary seconds at the light; all is good. 

Big Hills

Being on the coast means everything runs downhill to the water. Since Olympia sits at the southern apex of Puget Sound and traffic flows around its eastern shore, I am facing major slopes in 3 different directions.  Now, most of this is all about knowing the area but when coming to a big hill, regen is unavoidable simply so how to take the greatest advantage? 

My process is actually probably not the best way as I tend to slow down all the way to the "maximum" legal speed limit which again affects the color of the local aura in a bad way, shifting to N which allows a quicker acceleration back to illegality then bounce from D to B to N as needed.  The big current hits from doing this is not a good thing for the battery as it will last longer. Realize you are pumping power equal to DC charging speeds albeit for shorter periods of time.  There are a few hills that have major arterial intersections at the bottom so traffic slows way down. In those cases, its generally less N and trying to stay in D so regen is lighter. 

The Choice Is Yours

All this may seem unnecessarily complicated and it is otherwise there would be no challenge. The next issue to consider is will all that shifting wear out the tranny? Well, no tranny so no tranny to wear out. But there is a drive shaft to the front wheels but that is NEVER disconnected even when in neutral so wearing it out? Not too likely. 

Now the key takeaway here is there is no single process that works if you are trying to maximize your efficiency. Conditions are constantly changing and each drive mode is designed to fit a very specific role.   The other key takeaway is that this is what works for me. You may decide to stay in a drive mode and simply control power flow to minimize regen. That does work but takes a lot of concentration, more concentration then I have. Others may find it easy to maintain that steady foot so its really all about doing what works best for you. 

Finally, I hesitate to present these numbers simply because there are too many variables to consider. I am a power miser during Winter, toggling defrost as needed, chilling ALL the time (but still comfortable) so my efficiency is higher in Winter than most because of me, not the car.  But my 2018 I had a LT average 4.72 miles/kwh over 25,185 miles.   Now my Plus is a bit of a different story as the extra range simply put my mindset into a situation where I felt like saving range on the freeway was no longer a thing so I became a criminal exceeding the speed limits by a "gross misdemeanor" margin quite frequently; something that VERY rarely happened in my previous four LEAFs.  

Naturally that caused a drop in efficiency and at 35,000 miles on the Plus, I am at 4.48 miles/kwh but have exceeded 5 miles/kwh two months in a row and expect no different for July despite the HUGE increase in A/C use. 

FYI; I admit to a bit of tongue in cheek in describing the scenarios above especially the "racing to red" stuff.  But one thing I have noticed is that a lot more gassers are doing the slow roll from light to light like me. Really started noticing it a few months ago. I wonder why? 

LEAF Plus 2 Year Review and Degradation Update.

 Birth day; Ahr 176.09 SOH 99.79%

One year; Ahr 164.28, SOH 93.13%

Two years; Ahr 162.57, SOH 92.16

6 month loss; Ahr 8.01, SOH 4.54%

1st year loss; Ahr 11.75, SOH 6.66% over 14,669.2 miles

6-12 month loss; Ahr 3.74 SOH 2.12%

2nd year loss; Ahr 1.71  SOH .97%  over 13,012 miles

For the impatient, I started with the pertinent data. See a trend here? Granted, its only 2 years so might be hard to interpret. How about a picture? 

The chart tracks Ahr/SOH readings every 1000 miles taking time out of the equation. Instead of tracking actual readings, I extrapolated the numbers to what they would be if the current rate of degradation was maintained to 100,000 miles.  I did this to create a visual representation of the rate of degradation which makes the data much easier to interpret. 

To put it simply; 

If the slope is flat, the rate of degradation is not speeding up or slowing down. 

If the slope decreases, the rate of degradation is increasing. 

If the slope increases, the rate of degradation is slowing down. 

As you can see, after 6 months (7099.8 miles), the rate of degradation has been constantly slowing down. It had been my plan to predict when the degradation curve would flatten and show data to support my prediction but my ability to gather info from other Gen 2'rs has not been as fruitful as I had hoped and instead of delaying this post (2 year anniversary was Nov 16, 2021) any longer, I decided the data collected will be used for a separate topic. 

 I drove 14,669.2 miles the first year, 13,012 miles the 2nd year. I am just under 30,000 miles as of now. If I were to assume the rate of degradation over year 2 from here on out (which we already know is not true) then my numbers at 100,000 miles would be Ahr 153.16, SOH; 86.66%. IOW, it would be a monumental challenge qualifying for a warranty pack.  Of course, time is also a factor so the projected numbers assume annual mileage of 13,012 miles matches year 2 as well. 

Price of Gas

Like before, I seek out free charging when its convenient for me and generally its a lot during Summer but not nearly as much during Winter.  This year has been different because EVCS is offering free charging thru out the Chademo ONLY West Coast Electric Highway until upgrades to CCS/Chademo (Yeah, that's right. Chademo lives!) are complete at which time they will offer WCEH special pricing. No info on that but the $20 unlimited plan is not likely to survive this change. 

I am also lucky enough to have 3 Electrify America stations in town where all the Chademos work; an increasing rare occurrence it seems.  So a visit or two on their free holiday weekends is almost a given. 

Because of this, I almost maintained a balance of public charging with AC winning at 871.147 kwh over DC's 720.4539 kwh.  All the AC was free while DC racked up $28.05 in charges. The "real" total is higher due to money on various accounts used but that money was spent long ago so not counted here since...well, the expenditure did not happen in 2021. 

On the home front only $154.95 was spent to charge the LEAF.  My highest cost per mile happened in Feb and for a few reasons and yeah, it was weather related.  We had a huge snowstorm which meant February also had the lowest efficiency at 3.86 miles/kwh, lowest amount of free public charging (37.46 kwh) and home cost all tier two electrical rates. Despite all that, I still managed an "eye watering" 2.58 cents per mile (Yeah, its gasser eyes that are watering) 

Speaking of weather, the 2nd lowest public charging use was June. This was a bit of a shock to me.  My free AC charging mostly falls into two categories.  Volta while at the movies or the mall and Telsa SC while biking the trail.  SC Lacey has 4 Chargepoints that provide 2 hours free charging when Target is open and it borders The Chehalis Western Trail.  Biking is not only good exercise but for me, its Zen for the mind so when the weather turns good, I am on the trail 3-5 days a week so lots of opportunities to grab some free electrons.  

But this past June was when we had our all time heat wave and it was a doozy. With temperatures well over 100º, I wasn't about to hit the trail or much of anything else for that matter.  During the heat wave, we had temperatures in excess of 30º above normal so it was all about hiding my LEAF from the heat in my "not so cool" garage but better than sitting in a parking lot during the hottest part of the day! 

From the heat to the cold, we just finished up a severe cold streak that included temps in the mid teens and nearly a foot of snow. Because it was so cold, snow and ice dominated the weather for nearly 2 weeks.  Despite all that, I ended December averaging 4.0 miles/kwh but was primarily on the strength of a trip to King County and a disabled vehicle in the middle of the 405 that pushed my efficiency to 4.6 miles/kwh.  My average over just the last week of December was 3.4 miles/kwh including a 2.4 mile/kwh day which consisted of mostly doing donuts around town as work was canceled so had some free time. 

2021 Expense Summary 

Miles; 13,254.6

Fuel cost (including public charging fees);  $189.00

kwh used; 2919.01

Miles/kwh; 4.54

Cents/mile; 1.38 (Due to deposits with various public charging vendors, my true cost "this" year was less) 

Maintenance;  ZERO

Upkeep (Car wash, fluid replenishment, wiper replacement, etc); $168

Tab Fees (includes custom Seahawk plates, park access and some other stuff I'm probably forgetting); $328.25

Title Transfer fees and sales tax;  $382.09

BMS

Nissan's BMS is designed to be user friendly which is a politically correct way of saying no thought processes, no options, no nothing. Then they made it worse by removing their one and only custom charge setting without an explanation and naturally we filled in the blanks as to why. So when I relay my manual BMS processes, this the typical response. 

"I never know when I might have to go somewhere so we plug in immediately when we get home so our car is pretty much fully charged all the time. We like it that way. Ready to go."

"I have charged to 100% since day one and my battery is just fine. I have only lost one bar in 50,000 miles" 

"Charging to 100% all the time is ok because the batteries are designed to be charged that way. That is why Nissan removed the 80% setting. It is simply no longer needed" 

I could go on for days and back when we didn't have 100 miles of range and few public charging options, a lot of the concerns were quite valid.  But the attitude persists with 200+ mile ranges and MUCH more charging options. Nissan doesn't help with their hidden capacities, very early dire warnings to plug in, etc. But that is how cars work. My Prius gas light came on about 3/16th of a tank. In a 500 mile car, that is nearly 100 miles. But we Americans tend to run out of fuel on a very regular basis so manufacturers will not be changing any time soon. 

So I take it upon myself to control the SOC range I spend the most time.  Despite this, my full charges increased from 2020 to 9 in 2021.  Now you know how many longer road trips I did...almost. I had more than few leaving home at far less than 100% SOC but that was due to where I was going, what I was planning and time frame targets, etc. But ultimately, my goal is "living in the middle" SOC range that is. 

How much I am helping my pack will likely take years to partially quantify. There are too many variables to driving style, location, terrain, weather, etc to compare my pack's stats to others (another reason I started the database of other LEAFers which was to be able to use THEIR PACK DATA) but I can say a few things that apply "most" of the time. 

**Location doesn't matter nearly as much as previous packs which is most notable in the "not quite Hell" areas where its hot but not extreme but even in extreme areas like Phoenix, Gen two packs are doing much better. 

**High milers benefit.  Most over the degradation curve drive  A LOT. By a lot, I mean over 30,000 miles a year.  On the flip side, very low milers are riding below the curve although that is not as predominant and an early indicator says those who started out low on the degradation curve are gradually catching up to the pack. 

** Time based degradation seems to have taken on a much greater role and the quarterly BMS adjustments seems to put an emphasis on that. For those unaware, unlike previous LEAF packs, the battery stats namely ahr and SOH do not bounce up and down several times a week like the gen one packs did.  Now the numbers would slowly drop but every 90 days or so, the numbers would change dramatically gaining or losing   chunks of rated capacity.  For lack of a better term, I labeled this phenomena as "The Adjustment" 

The Adjustment 2021

In my 2nd year the adjustments were kinder. MUCH kinder.  Unlike the 4 in 2020 which were all drops, 2021 was a split with 2 drops, 2 increases with the overall change of nearly zero. (-.09 ahr, -.05 SOH) leaving only the downward drift between the adjustments to account for the year's capacity drop which was also better in 2021 so very much a win-win or simply the BMS learning my habits and needs and adjusting accordingly?  The answer to that is a mystery to me so I am going to data dump ya and you can make your own conclusions. 

Now that we have 2 sets of numbers to look at, some interesting statistics.  First off, can't say how invaluable LEAF Spy is for this kind of stuff. I have archived EVERY LEAF Spy session covering all 5 LEAFs I've had (realizing of course LEAF Spy wasn't here in the early days of the 2011 and 12's) so being able to go back years to look for a specific data point is simply awesome.  Below is a spreadsheet on the adjustments and it seems like every time I update it, I add more stuff to it. Not sure if the stuff is pertinent or helping to obscure the obvious but at least I can and LEAF Spy is the reason why. 

First the chart

Adjustment Change Log

As always, you can click on the chart for a bigger, easier to read version. Ok, most of the headings are self explanatory so what I have going here

Adj Length; How long the adjustment lasted

Days bet adj;  Should be obvious if you understand my abbreviations; days between the end of one adjustment and the beginning of the next

ahr and SOH change; Change during the adjustment

ahr daily and SOH daily;  Change between adjustments

The rest of the data is how I charged between adjustments. Trying to see if too much DC was a bad thing. As you can see, I went way overboard on both options and basically determined its not what you charge with, its how you charge.  A lot of DC is probably fine as long as you are charging to a reasonable level. In my case, my target SOC was generally 70% which basically kept the batteries surprisingly cool. More on that later.  When collecting LEAF Spy data from other Gen 2's, I found no change in degradation rates based on the amount of DC charging. Maybe it was a change in NCTC or simply the additional range made it easier to pass up stations but hardly anyone relied even moderately on DC charging.  Now more than a few of you will say DC charging is bad since that is also when I lost most of my capacity but my loss is not out of the ordinary even among people who DC'd rarely if at all so keep in mind, there is a lot  more data going on than we see here. 

Notice the date drift?  More evidence its closer to a 90 day cycle than quarterly. Will need another year though to verify. 

Interesting that I have had two one day adjustments both in October? One up, one down. 

Speaking of the Oct 2021 adjustment; the gain only brought me back to even when considering the daily losses. Started the adjustment period with an ahr of 162.68 and ended with 162.66. 

My largest negative adjustment was January of both years. This is a time of year where I generally drive less. Makes me think the car is hiding capacity from me to protect the cells maybe? More on that later. 

In all metrics; Year one was much more severe than Year two. 

Loss during adjustment;  

2020 ahr; 8.79.       2021 ahr; .09%

2020 SOH 4.98%.  2021 SOH; .05%

Loss between Adjustment;

2020 ahr; 2.77.        2021 ahr; 1.57

2020 SOH; 1.62%  2021 SOH; .92%

So the real question now becomes will it continue to improve in year 3 or stay consistent? 

**NOTE**

Not all numbers will jive with the above due to offsets of years, adjustments, etc. Top section is "birthday" stats based on the November 16, 2019 delivery date.  These numbers here based on adjustments with the projected build date of approximately October 25, 2019. 

Niggles

Ok so the car still has quirks. Listed below in no particular order. Only mentioned because...well, its a reality. Nothing here really matters a whole lot to me. Its like my phone. It doesn't always stay in its lane but the road is empty so not a priority for me. We all have our levels of acceptance so YMMV. 

Steering wheel volume controls randomly do not function. Never lasts more than a single power cycle and ! still have the old school knobs which always work so guessing I have to say...Glad it aint a Tesla! But then again, they probably use an entertainment system with a higher degree of reliability. 

When playing SAT radio, I will see random reboots of the center screen that I can just about predict to the second. Doesn't matter. With constant signal drops, its a bit irritating to listen to so I have passed on the last half dozen freebie periods. I will say Amazon Prime music seems to work quite flawlessly.  Most of the time, I am listening to news radio anyway. 

Air flow changes on its own. Seems to happen a lot more during Summer with A/C then any other time of the year so wondering if its simply a bad circuit design or insufficient ventilation causing issues due to heat buildup although I can't say that I have had experience with OEM equipment that even needed ventilation?  Who knows?  But it happens. 

Huggables

As the years roll by, I have lost perspective on a lot of reasons why I love EVing. But the horrors of the alternative comes crashing back immediately after cranking up a smoke machine.  With 3 distinct drive modes, driving has become a bit more fun. Its become a challenge of mine to go an entire month without touching the brake pedal one single time. (after startup of course) I am approaching my 4 year anniversary of E Pedal (2018 delivered February 16, 2018) and have yet to make it although I did make it past the 20th 3 times. 

The Drive

My driving style has morphed during that time as well going from nearly 100% E Pedal to B Eco to the current D/B Eco. My change was encouraged by talking to John, a 2015 LEAF owner who rolled 200,000 miles on his original 24 kwh pack with 11 capacity bars.  

11 BAR 2015 LEAF with ORIGINAL BATTERY PACK! 

And no, there is no typo in that last statement. Its a monumental achievement and so understanding how he did it was a no brainer.  He charged to 100% every night at home, charged to 80% on DC to make it home every day.  So what was his secret?  Well due to his location, it was better to take the state highway to work than I-5 which would require driving thru a half dozen daily bottlenecks.  The state highway was also a bit shorter but slower. Speed limit was 55 but slowed to a crawl driving thru every small town on the route. He admitted it took a bit more time but was also a much less stressful drive. 

This got me to thinking on what effect higher regen and the accompanying higher level of power to regain speed had on the rate of degradation?  We all know that cycling is a factor and one charge cycle rated as 0 to 100% so two 50% charge/discharge cycles is one cycle, 3 charging sessions adding 25% is one cycle, etc. 

So my year 3 experiment (actually started last June) will be minimizing regen as much as possible. This means my primary drive mode is D Eco. I still use them all including N but the one thing I realized during my driving is I am constantly evaluating other drivers and predicting what they are going to do which causes me to completely remove my foot from the accelerator frequently for no more than a split second and I was doing this a lot. Since D has the flattest regen profile, I figured a smaller hit to the pack has to a good thing, right? 

Projects for 2022

The big thing will be the driving style adjustment but when doing random experiments, I stumbled across other observations I will be repeating to see if its a fluke or simply an unnoticed fact of life. 

One thing will be charging efficiency and how it relates to SOC.  I saw a rather drastic variance on DC charging efficiency as the SOC rose. Efficiency would start out quite high but in charting a DC charge curve on EA one day, I noticed that my ability to predict the time EA would flip over on the Kwh counter was rather flawed. I kept missing it and couldn't understand why.  So looking at the data later, I found that at high SOC, the charging efficiency was dropping significantly.  I hadn't noticed because I so rarely (like nearly NEVER!) DC above 90%.  So will be charting that to eliminate random car flukes, LEAF Spy data, batt temps, and whatever else I can think of. 

Of course my pursuit of RapidGate continues. I didn't have a good chance at that last year mostly due to EA's dumbing down Chademo to 120ish amps.  When 200 is possible, its hard to quantify if you can't stumble across a 200 amp machine conveniently located in the right spot.  My Tahoe trip was derailed by wildfire although we did do the 10 Falls Hike in Oregon during REALLY hot weather but apparently it wasn't far enough and we did spend the night (although the overnight low was in the upper 80's) which probably made the difference. Even a few side trips home the next day didn't really matter. I will say I was surprised at how well the pack managed in 100º temps at 70 mph though. 

HELP!!!!

Still need more LEAF Spy participants! The only way I can make this work is I need the same person to submit several data points over YEARS. Anything else is simply interesting.  So thank you if you have been submitting shots on a regular basis...all 5 of you...Yeah, only 5 of you. 

Another thing is if you have been saving your logs on Dropbox or something, you can pull out significant data and post them as well. 

Date,  ahr, SOH, HX, miles and L1/L3 count and I can work with that.  Doing this gives us a better picture of how driving style, climate, location, and charging habits affect us. John is a perfect example that none of us really knows where the ceiling is. Did he simply win the traction pack lottery or is he the reason he has done so well?

Until next time! 

Gen Two LEAF BMS draft

 As soon as the Gen two LEAF batteries hit the streets with the 40 kwh 2018 model year, it was quickly apparent that Nissan had moved into an entirely new direction with battery management. Despite the pack being larger which implies more ability to take a faster charge longer, that did not happen. The DC charging knee on the 30 kwh packs was greater than 80% SOC. This made getting a significant boost in range in a reasonable amount of time quite easy.  One no longer had to wait until the SOC range was near zero to enjoy all the current the station had to provide. So it made sense that it would continue in 2018. But the knee dropped to no more than 70% SOC and depending on the temperature of the pack, could be as low as 45% SOC. As a reminder; the knee is the point on the charge curve when power stops rising because the current is dropping.  

Crazy BMS

The Gen One BMS would generate battery stats that bounced around on a near daily basis. changes of 2 or 3% within a few days was not uncommon. This led to some crazy theories of what was or wasn't good for battery health. But the  one thing that didn't seem to happen was a change in the range of the car. Maybe there was a change but I never noticed anything significant or more importantly anything "usable."  Now, I had 6 years experience with 24 kwh LEAFs and noticed a drop in range that was not all that extreme but in retrospect, the range was so limited that a bit more limitation didn't really impact my thinking. I had to charge on the road frequently to do my job when  the  pack was new so... nothing really changed when  I lost 10% of my range. 

On  the flipside, my 2016 S30 never had any discernible degradation over the nearly 30,000 miles I drove it and those miles were piled on VERY quickly. It was the best pack I had and I missed a great opportunity to find out how far Nissan had progressed. 

January 2018 116.2 miles on a single charge during "less than desirable" winter weather. Don't let that bar fool you. I was plugged into the EVgo DC at Tacoma Mall when I snapped this pix. 

82.34 ahr is the new pack parameter and that is where it was 400 miles and 3 days later 

when she was killed on the streets of Tacoma, WA. This was the 14 month LEAF Spy

shot. 

RapidGate, IceGate, And Adjustments

As we now know, DC charging was no longer predictable as it once was. The Gen two packs introduced a concept known as "RapidGate" which reduced the starting current on a DC charge when the temperature of the pack was "warm" at the beginning of the charge.  The 40 kwh  packs would see as little as 1/3rd the normal current on its 2nd or 3rd DC charge of the day.  Although the ramp down in current was more gradual, the slow rate of charge frequently doubled the time of the stop. 

But that was only half the story. I don't make it a habit of camping at charging stations. 95% of the time, I don't have the patience to sit in my car watching my SOC inch upwards so I have a routine where I do double duty on charging by taking care of personal needs and desires.  It was one of these times during the winter I noticed that I was already past the charging knee on my return 15 minutes later.  So I started tracking my starting battery temperature and when the knee happened and discovered "IceGate" where the charge starts to slow as low as 45% SOC instead of the near 70% we would see in ideal conditions when the pack was in the low to mid 80's ºF. 

Now the Bolt has issues in cold weather but speeds up when the pack heats up. The LEAF? Not so lucky. Several experiments both verified that RapidGate and IceGate are tied to the temperature of the pack when the charge begins.  So plug in, charge 5 minutes to gain a bit of warmth, unplug and restart the session? Well, tried that and it didn't work but only tried it twice. I am not done with that theory but that is a good 6 months down the road (I didn't do "any" DC charging this past winter) 

Gen Two BMS Goes In A Whole New Direction

 Gen One packs would retain their "new pack status" as much as several weeks so the parameters for ahr and GIDs were fairly well known parameters But the Gen 2 packs starting with the 40 kwh in 2018 changed all that.  As I always did, I recorded LEAF Spy stats the very first minute I sat in my new LEAF and I am glad I did because those numbers would not appear again.

The very next day after 93.5 miles of driving I was at 175.99 ahr and 99.77% SOH and the slow decline had begun.  So will your plus look like mine when you pick it up? Doubtful...in fact, VERY doubtful. Its been nearly 3½ years and there is still no real consensus on what the new Gen Two pack parameters are. Like my 40 kwh, the LEAF Plus BMS would run in two distinct modes;

Daily Mode

The ahr and SOH drops slowly or remains the same. They NEVER go up...EVER. Not even a single .01%. No amount of warm weather, temperature, DC charging, heavy use, or very light use would change this pattern.  All the things I just mentioned were used as theories on how to "boost your range" on the Gen One packs and yeah, they might have moved the battery stats up or down but an actual boost in range? Not sure anyone ever proved that. 

TBT, it was all quite boring. I mean I started only recording SOH and ahr only when it changed. My log was filled with a ton of blank spaces. Grasping straws, I started logging "longest stretch with no change" Yeah...I was that bored!

The Adjustment

Just as I was falling asleep at the log, some excitement came along... the bad kind. Just before my 3 month anniversary, I hopped in my car, started it and did the daily LEAF Spy recording and had to do a double take. 

I seriously thought I would drop a capacity bar before the end of the month! I had no idea what I was doing wrong! The only full charge the car ever had to this point was the one at the dealership when I picked it up (remember this!) 

When it finally stopped, I breathed a huge sigh of relief and continued on my merry way. It was winter which means a lot less driving than normal so I was over 70% SOC very infrequently as the plus range was more than enough to cover several days of usage even at that modest SOC.  But "exactly" 3 months later on April 25th, it did it again! This time it wasn't nearly as dramatic and only lasted 3 days but I was on pace to only have 55% capacity remaining at 100,000 miles. It was then I realized that something was off. VERY off. 

Experiments 

Since this was my 2nd Gen Two LEAF pack, I kinda already knew what to expect. Large early drop lasting 18-24 months that eventually drops to 1% a year more or less.  So when picking up my Plus, I started formulating experiments to see if charging/driving habits would change anything. By now, Nissan was very aware of LEAF Spy and its growing list of followers and I have to think they weren't extremely happy about that. As mentioned earlier, too many of us were using LEAF Spy stats to evaluate how well we were doing on our charging habits.

Gen one packs hid true pack parameters which explains why gen one packs would retain the new pack numbers for several weeks or more.