The Participatory Science Platform has again stepped up to help Flip the Fleet! The Otago Science into Action partnership, headed by Otago Museum, allocates funds from the New Zealand government’s Curious Minds portfolio to support participatory and citizen science in Otago. The funding helped us get established last year, and now will help us figure out what is happening to Nissan Leaf battery health and what to do about it.
Naturally we are stoked – the battery health issue is puzzling and important, so it’s a relief to be able to test some ideas about what is causing the apparent rapid decline in battery health in the 30 kWh cars (see https://flipthefleet.org/2018/30-kwh-leafs-soh-loss/). There are three main parts to the work:
- Tests of the reliability of battery ‘State of Health’ as a measure of energy holding capacity of the battery
- Fitting “EV Black Boxes” to monitor their battery temperature, charge levels, and change in battery State of Health.
- Developing a battery care strategy for each participating family or business.
Thanks to all the new owners who have signed up or started scanning, we now have lots more data coming in. This will allow a revised and improved statistical model to be published shortly, so please keep the scans coming in the meantime. The colder weather is expected to cause the SoH to dip, and also reduce energy efficiency (km/kWh), so recent drops in your SoH and range will be partly related to season rather than battery degradation.
Checking the instruments
Originally the tests were to be completed by Walter Larason (EVs Enhanced) by calibrating the measures using a dynamometer – here the cars are run under tightly controlled conditions (same temperature, constant current discharge) to measure the total energy discharged when draining a fully charged battery until it is absolutely flat. He has made a great start on these and you can read about them at his EVs Enhanced Facebook page at: https://www.facebook.com/evsenhanced/. Originally we had thought that a small part of this work would be funded by the PSP grant, but things have changed a lot since Nissan announced a firmware recall. Walter now prefers to fund any further tests himself. Accordingly we will complement the information from Walter’s workshop and dynamometer tests with data we will gather from run-out tests in semi-controlled conditions, partly at the EV owners gathering at Highlands Motorsport Park on 9th September.
Monitoring battery temperature
The EV Black Boxes were developed by Vasily Levshin (Exact IOT Ltd) with funds from the Government’s Low Emission Vehicles Contestable Fund, administered by the Energy Efficiency and Conservation Authority (EECA). Our working hypothesis is that the 30 kWh battery’s health is particularly sensitive to warmer temperatures when held at high charge. The EV Black Boxes will track the battery temperature every minute in twenty-eight 30 kWh Leafs and four 24 kWh Leafs as they are driven around Otago through this winter and into next summer. The EV Black Box also measures battery temperature every minute throughout the charging cycle when when the car is switched off, so we can calculate how hot the battery gets throughout each day and week and season. We are looking for volunteers from throughout Otago to install the EV Black Boxes – please email email@example.com if you want to help in this way. We can build some more EV Black Boxes for Leafs and eNV200s outside Otago, but these people would need to pay for the set-up (the PSP grant can only be spent in Otago). Please enrol at https://flipthefleet.org/ev-black-box/ if you want to help the research this way. This would be your donation to the research and greatly increase the statistical reliability of the results. It also helps to have samples from all around New Zealand that experience different climate.
An EV Black Box is tucked away out of sight in a side panel of the Leaf or eNV200 and from then on can be forgotten. Over 130 data fields are transmitted, including the charge in all 96 cells in your battery pack, battery temperature, efficiency of travel and battery ‘State of Health’ .. a real feast of numbers for us science geeks!
Making sense of the data
The team’s statistical modelling is led by Daniel Myall (NZ Brain Research Institute). He’ll put all those data together to devise a charging regime that meets each family’s and business’ need for the car while minimising the rate of capacity fade in the battery. It’s all part of reducing ownership costs and minimising the unwanted environmental impacts of making batteries by making them last longer.
A community rally in Cromwell on 9th September
The Otago Museum grant, and sponsorship from Highlands Motorsport and ChargeNet NZ will fund a rally at Cromwell on Sunday 9 September 2018 . It will be a fun family day out with as serious scientific bonus. We’ll use the Highlands Motorsport Park (http://www.highlands.co.nz/) to do various tests of the vehicles’ instrumentation and efficiency. Using the race track helps standardise the tests and keeps people safe. ChargeNet NZ will offer free charging at their Rapid Chargers to all the participants traveling to the venue on the 8th (or 9th), and home again on the 9th September. Thanks folks!
The day will be co-organised by the Otago EV Incorporated Society and Flip the Fleet, and will be Otago’s main contribution to International Drive Electric Week. We are hoping for lots of people to bring their EVs to the rally – all types of EV are welcome, but we’d particularly like to include as many 30 kWh and 24 kWh Leafs as possible. Please RSVP to firstname.lastname@example.org if you are interested in attending. It would be ideal if some people reached Cromwell the night before and had their cars fully charged to start by 9 am on the 9th September. Others coming in that morning may need to charge up fully before starting. The event will finish about 2 pm.
Duncan Carncross will bring his “Dubious Device”, a home built electric roadster, to Cromwell to show alongside a few other speciality EVs. But the main event will be us all circuiting for science in our family wagons.
Where’s the funding going?
The Curious Minds grant is for $20,000. Most of this will go into purchase and connection of the EV Black Boxes and running the Highlands Motorsport event. A small amount remains for the main investigator’s costs, but in reality, Danial, Dima and Henrik are contributing nearly all of their time for free. We all do that cheerfully to try to help EV dealers and owners who are carrying the cost of the 30 kWh battery scare, and to try to minimise damage to overall EV uptake in New Zealand.
Henrik Moller, Daniel Myall, Walter Larason, Vasily Levshin and Dima Ivanov
20 May 2018.