uktaxi said:
2011 Nissan Leaf now being used as a taxi in the UK with just over 32,000 miles on the clock. Getting regular rapid charges per shift (3 or more). A lot of the time these can be 15 minutes (or less) 'top up charges' between jobs.
Just ran the LeafSpy app for the first time and it shows a AHr of 59.34 & GIDs 247 (87.9%).
Thanks for the report.
Hope you will come back with more in the future.
First, realize that the app is not measuring your battery capacity, it is only displaying what your LEAF's own battery management system is reporting, along with whatever errors the cheap instrumentation produces.
The limited accuracy of using the "gid" count as an indication of
actual battery capacity has been known for years.
Ingineer:
The biggest problem with the Leaf's Instrumentation/BMS (in my opinion) is the use of the Hall-effect current sensor. These are not very accurate for coulomb counting and subject to accuracy degrading effects, such as centerline drift, effects of the earths magnetic field, temperature, etc. The inaccuracy of this is why "some gids are more equal than others". Nissan compensates for this inaccuracy by applying corrections to the SoC by sampling voltage and using it formulas that also take into account the temperature, internal resistance, aging, etc. This is why you can gain/lose SoC suddenly sometimes after power cycling. It will apply changes all at once if the car is power cycled, but if in use, it will apply a correction in the form of a drift which appears as faster/slower SoC counting than real energy out/in.
I was able to meet with the Nissan engineers from Japan last December, including the battery system engineer (I had a one-on-one with him). Their explanation for why we have no direct SoC display in the car was basically that they were afraid to show it and have these corrections occasionally make it "jump" which would "confuse the customer". The Battery Systems Engineer told me that cost was the reason they used the Hall-Effect current counter rather than a more-accurate galvanic shunt...
http://www.mynissanleaf.com/viewtopic.php?f=31&t=10040&start=61" onclick="window.open(this.href);return false;
Second, look at the AVT test results of capacity loss through 50 k miles in batteries with atypical use patterns similar to yours:
http://avt.inl.gov/pdf/energystorage/DCFC_Study_FactSheet_50k.pdf" onclick="window.open(this.href);return false;
As discussed here:
http://www.mynissanleaf.com/viewtopic.php?f=27&t=14271&start=20" onclick="window.open(this.href);return false;
You can see the relatively slow loss of capacity except during the seasonal periods when they experienced very high battery temperatures caused
both by high kWh throughput (multiple L2 or DC sessions and high miles driven daily) and extremely high ambient (Phoenix extended Summer) temperatures.
During the 10,000 mile driving segments where the batteries were not subjected to high ambient temperatures, capacity loss was only in the ~2 to 3 percent range, even for the LEAFs subject to twice daily DC charges from ~driven-until-stop SOC to "100%"
So, you should be able use the App to monitor your batteries temperature this summer to get a good idea of what to expect in terms of future actual capacity loss.
When was the Cab first put into service?
Has it already gone through a Summer of DC charging and high daily miles?
Have you observed any loss of range?
