Dear test drivers, kia ora koutou kātoa
We’re on a roll
The Flip the Fleet collective continues to gather a life of its own – 54 test drivers are now helping. Many are back-loading data from log books so we are retrospectively getting more data sets uploaded than there were participants in some past months (Fig.1 attached to this Email). We could still do with some more iMiEVs, i3s, Teslas and Zoes to give the KPIs for them a stronger test, so please shoulder tap friends or colleagues with those gems in their garage. Ecotricity joined as a fleet, and they have data from the first Leaf in New Zealand – welcome! There were a few more gaps than previous over the holiday period – please upload your data for December and January if you have the records but haven’t entered them yet.
Battery State of Health: this month’s example of how we will use your results
Your battery’s ability to hold energy, and hence your maximum range between charges, is expected to decline at some (as yet unknown) rate affected by accumulated age, distance travelled, your charging patterns, local climate and perhaps treatment before it was imported to New Zealand. Some would-be buyers of LEVs are put off by the fear that their car will soon be useless or have a low resale value if the range contracts severely. Flip the Fleet can help by measuring the rate of battery degradation to dispel myths and build confidence to buy electric.
Several Leaf and Outlander owners are monitoring their battery’s State of Health (SoH) using dashboard decoders and apps like LeafSpy and EVBatMon (measured as a % of the original energy holding capacity at time of manufacture). Here are some results from the test drivers:
- Some batteries are indeed showing gradual decline in SoH. For example, SoH of a Gen 1 Leaf (labelled ‘LeafG1#4’ in Figure 2) has dropped by 11% over the past two years; and another (‘LeafG1#5’in Figure 3) dropped by 5% over the last year and a half : we will eventually be able to predict when they will need to upgrade or swap their battery in order to retain their minimum practical range, and how that varies between models and regions.
- But take a look at the LeafG1#3 in Figure 3! Its SoH stayed relatively stable for 2.5 years – we know that this owner is following a very strict and low stress charging regime.
- There are bumps along the way! Sometimes the SoH jumps back up a couple of % before dipping again. Rebuilding of SoH can be quite strong – see the way LeafG1#4 climbed from 92% to 98% in 2014 after a prolonged period on a showroom floor or store (Fig. 2). LeafG1#1 also regained battery health in recent months (Fig. 3). We’ll build “regression models” to smooth out these bumps and calculate “statistical power” to estimate how many monthly measures of SoH are needed to reliably estimate rates of SoH declines. In the meantime we urge you to regularly measure the SoH rather than rely on a few measures – this will avoid being misled should you happen to measure during one of the bump ups (or dips) and so become complacent or unnecessarily alarmed about how your battery is faring.
- We don’t have many SoH data series for Outlanders yet (see the best two examples in Fig 2) – this is an important gap nationally because Outlanders are shaping to be the main PHEV component of the NZ fleet.
Software changes: getting our act together
We are currently working to streamline data uploading and working up more varied environmental outcome calculations for future months e.g. How many “virtual trees” have you planted in terms of equivalent CO2e emission savings by running an LEV? How many cows’ GHG emissions have you compensated for? One of our test drivers (from Zero Waste Ltd.) has offered to design a KPI around full life cycle (‘End of Life’) measures for tyres – she’ll probably calculate the time it takes for your EV to offset the making and disposal of the tyres. Please follow her example by telling us how you want to calculate LEV benefits in some human-scaled way.
Your last 1-Click survey will help shape policy
Results of your last 1-click survey on lane privileges for EVs were summarised in a submission to the Parliamentary Select Committee and MoT which you can read at www.flipthefleet.org/discussion. Flip The Fleet has asked to speak in the Select Committee hearing – In order to save air miles, we hope that some of our Wellington contributors would be willing to present the case on our joint behalf- please contact us if you can help.
With best wishes, thanks and utmost respect for your effort to help flip the fleet.
Dima and Henrik