="asimba2"
edatoakrun said:
That being said, I think they are consistently wrong, in showing an ~12.5% loss of capacity, which has not shown up in my LEAF by either recharge or range capacity tests.
="asimba2" I just want to confirm I understand what you are saying. Leafspy shows a 12.5% capacity loss but 2 other tests (wall input & range test) shows less?...
Correct, but you are quoting results from over two years ago, when it was already obvious I probably had a significantly higher % of "new" capacity than my LEAF's LBC was reporting, but it was not possible yet for me to accurately estimate my actual loss of capacity.
="asimba2"...That's kind of where I'm at. I keep track of what percentage of the battery it takes on certain routine trips. Even though Leafspy is showing 11% capacity loss, I have noticed no degradation in driving range...
I experienced
no significant range loss in my driving (which is at lower speeds and with far more ascent and descent than for most) until I replaced my tires in July 2014 at ~29 k miles. My current range loss is much lower than my estimate of capacity loss (~13%, as per previous post) and I think that suggests that my 2014 ecopias have lower rolling resistance than my 2011 tires did, at equivalent levels of wear.
Vehicle efficiency is not constant over time, especially at lower speeds (and unless carefully normalized, neither is driver efficiency) so range tests have not been as useful for me as I initially expected, to determine my pack's relatively small decrease in battery capacity.
="asimba2"...Tell me if my method is somehow meaningless--using the dash display for SOC in %, I know that when my car was new it would charge to 80% and I almost always had 55% left in the battery when I arrived home. Fast forward to today and I still arrive home with 55% of the battery remaining. I would expect it to take 11% more battery if that amount of degradation had occurred. Yes?...
My 2011 does not have a dash SOC display, but it sounds like (from reading others' posts) that that display (like my 2011's dash charge bars) may be informed by the LBC's gid count, so all my comments from here on should be checked to see if they also hold true for 2013-on LEAFs.
As I mentioned previously, I never rely on the LBC as an indicator of kWh use or remaining battery capacity.
When I compare the nominal kWh use reported by my nav screen as I drive, (2011-12 LEAF dash m/kWh has the ~2.5% underreport error in miles driven as is reported by Carwings, which is why 2011-12 LEAF owners should never use dash m/kWh without correction) to the LBC reports it is obvious that gids contain such variable nominal Wh content (I've seen from ~ 40 nominal Wh to ~100 nominal Wh per gid, over ~ 20 miles of driving) that LBC reports are not useful for accurately calculating current capacity, or range remaining.
The only consistency I've seen in gid/nominal Wh content, is that the LBC always over-reports nominal kWh use at the top of the charge, and under-reports it for energy discharges from lower SOC.
In other words, from my LEAFs LBC reports, gids always have contained more nominal Wh when from lower SOC, than they do at higher SOC, when I have measured various segments of my available charge capacity using range/capacity tests.
So, if Nissan's engineers intended gids to be a display of units with constant Wh content, they failed, at least in my LEAF.
But quite possibly (IMO) at least some of the wh/gid variability was intentional, and just another means by which Nissan sought to
fool the driver into avoiding excessive relience on the bottom of the pack.
Another suggestion that wh/gid variability may be intentional, is in how it seems to vary ~consistently with certain driving conditions.
I've only seen very low Wh/gid from the LBC at the start of trips beginning with large descents, resulting in unsustainable (but mathematically correct) double-digit m/kWh nav screen reports.
It seems likely to me that Nissan engineers did not want external energy sources such as energy from descent (or maybe even a high-speed tailwind...) to be accurately represented in the LEAF's dash capacity bar display, lest the driver get unreasonable expectations of future range remaining.
Now, as to nominal kWh use reported by my 2011's dash, nav screen and Carwings reports, I have never been able to detect any variation in Wh content
over a single charge cycle with a range or recharge capacity test. I expect there are errors in the reports, but they are just not large enough for me to see over the other
noise in every range/capacity test.
However, while my LEAF's nominal kWh use reports are reliably constant in Wh content over a single charge, and over subsequent discharge cycles
in the short-term, there definitely seems to have been a change in Wh content/nominal kW over time, which can be observed by my LEAFs decrease in reported charging efficiency, which can be observed by comparing the use reported by a meter before your EVSE, to the nominal kWh use as reported by your LEAF.
When my LEAF was new, each nominal kW (reported on dash, nav screen and CW energy report) actually held fairly close to 1,000 Wh, as I saw from my first range/capacity test:
My earliest range test, on a hot Summer afternoon:
On 9/7/11.... When I reached my driveway, at 87 miles, I still had (less than) one bar, so I drove until I got the "very low battery" warning and simultaneously lost the last bar, at 91.5 miles. I got home with 93.4 miles, and between 5,500 and 6,000 ft. of ascent and descent, at an average speed of about 40 mph (those last 6.4 miles were up and down a hill at low speed). Since the last 1.9 miles after the "very low battery” warning were at about 20 mph and required about 150 ft. net descent with regen, I was probably still very close to the VLBW point capacity, when I parked.
According to CW, on this drive I used 18.7 kWh to drive 91.1 miles at average energy economy of 4.9 m/kWh.
I rechecked 2 other recent drives of 85-105 miles and each time CW has erred, under-reporting distance traveled, as compared with both my odometer and Google Maps, by 2.5%, +/- 0.1%.
Extrapolating from the chart, it appears CW may be saying the 1.7 kWh (8.5% from the chart, of 20.4 total kWh-anyone have a better number?) I had left at or near VLBW implies total available battery capacity of about 20.4 kWh...
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The most significant correction I'd make today, is that I have since range-tested the capacity from VLBW to turtle (but coarsely, and only once) and that seems to be closer to
~2.0 nominal kWh, so I probably had ~20.7 nominal kWh available to turtle, on that day almost four years ago, and to reiterate, each of those nominal kW probably represented fairly close to 1,000 actual Wh,
at that time.
Almost four years later, the same dash, nav screen and CW energy reports from range/capacity tests driven on ~the same route now seem to be reporting (as best I can estimate) ~11% error, each
nominal kWh now actually containing ~1,110 Wh, per kW from the meter (as reduced by the cycling efficiency shown by AVTA testing) and ~the same error shown by my LBC, over-reporting ~24% capacity loss, rather than what I believe most likely to be ~13% actual capacity loss from new.
That's ~13% down from the ~23.4 kWh average reported for 2011 LEAF packs tested by the AVTA, and more like ~15.5% down from the 24kWh spec.
This all assumes constant charge/discharge efficiency over time, which is another variable, a reduction in which probably means my actual capacity loss is slightly beyond ~13%.
But very unlikely, IMO, that cycling efficiency has decreased by ~11%, which would require explaining why my battery doesn't seem to be heating up much more than when new, during the charge/discharge cycle, and why my 10-bar-battery LEAF, on a warm day on a slow-speed route, still covers 100+ miles, in range/capacity tests, using only the ~87% (currently) of my total charge available, from "100%" to VLBW.