Is Morris Garages deceiving EV customers?
Misrepresenting data harms the customers
Housekeeping
New merch - HEPA filters for MG ZS EV are selling out fast. Last few left to be dispatched in the current production run. Order them now.
If you’d like to request HEPA filters for other cars, then please let me know.
What’s cooking at MG?
MG provides vital car data on the On Board Diagnostics port (OBD). I’ve argued why this data is crucial and how innovative products can be built around it. One such metric available on the OBD is the State of Health (SoH) of the High Voltage battery pack.
The SoH of the 2022 ZS EV Facelift car goes down ~0.0102% every day.
The data by MG isn’t a marker of SoH but a marker of how old is the battery pack. The company is misrepresenting data which is crucial in warranty related cases, insurance cases and resale of electric vehicles. Their system design shows that there’s little weightage on the charging patterns, external temperatures etc and more weightage on how the battery pack ages.
Before we dive into the data, let’s understand what is SoH and why is it important.
State of Health
SoH helps one understand the battery capacity of the car. A 100kWh battery pack with 85% SoH can dispense only 85kWh of energy when fully charged. A new battery pack with 100% SoH would dispense 100kWh of energy.
As the battery ages, the capacity to hold charge reduces. Continuous fast charging will also have an impact on the SoH. There’s no clear guidelines on what this means for the ZS EV, but Windsor has an advisory to slow charge their cars after a certain number of fast charging sessions. The ZS EV battery pack is from CATL SAIC JV whereas the Windsor’s pack is from Octillion. Tata cars, ie Punch EV also get their battery packs from Octillion, and come with a similar advisory. Drop me a message if you’d like a deep dive on Octillion.
Continuous exposure to extreme temperatures, high or low, will stress the battery pack, thereby impacting the SoH. This gets further amplified if the cooling or the heating of the battery pack isn’t upto the mark.
Long durations of non usage can negatively impact the capacity of the battery to hold charge.
The data that represents the age of the battery pack is being used to wrongly identify as the health of the battery pack. If a customer is getting poor range for any reason, they will find it very difficult to convince MG that the battery pack is at fault. The SC will always look at this “SoH” metric and say that it is within specification.
A customer with not much degradation will also not be able to discover the real value of the car in the second hand market. Any smart buyer will look at the car’s SoH and see the “degradation”. Higher SoH indicates higher retention of the battery capacity. If someone would like to just sell the most expensive component of the car - the battery pack - they too will be deceived due to these SoH readings.
Data
Here’s a link to the spreadsheet. You can copy the data and play around with it. Here’s the link to the interactive chart.
The OBD data was collected from 16th July 2024 to 29th October 2024. The OBD data and the dates of the measurement led me to an average of 0.01% degradation per day, irrespective of whether the car was majorly stationary or doing road trips with back to back fast charging sessions.
The data from the service center during the 60,000 km service tracked with the measurements from the OBD app. The service center reads the data from a proprietary software after connecting to the OBD port.
This gave me confidence that the data by the app is also something that is read by the MG’s team. Using 0.01% degradation per day, I back calculated the SoH. The value was 104.77% at the date of purchase. The facelift 2022 MG ZS EV was newly launched and deliveries had started mid April onwards. It is safe to assume that the production of the car would have happened early April. The SoH also tracks to 105% in early April.
Similarly, this SoH will show ~75% at the end of eight years from the date of purchase, just enough to avoid battery warranty claims.
Similar signs of degradation are seen in other MG cars in India (unverified by me) and various MG forums in UK.
The battery warranty terms are not clear in the manual. There’s no definition of what consists internal quality standards. This is anti customer behaviour and MG should clarify what these are and what are the clear terms and conditions for a user to claim battery pack replacement, should there be a need to.
Let us look at other visible signs of degradation in the car. The guessometer shows full range of the car as 400 km in the ‘normal’ mode. The car started showing signs of battery degradation in April 2024 at the start of my Delhi - Kolkata road trip.
It started showing 398 and it is now at 393 km in a matter of 6-7 months. While charging, the battery needs additional time to balance the cells after it has reached 100% state of charge. Once the cells are balanced, then the car is expected to hold charge at its peak capacity, thereby showing the maximum possible range on the guessometer. A few entries are marked on the interactive chart where it is likely that the cells were not fully balanced.
“Software is the achilles heal for Chinese OEMs. SoH is not so simple to calculate, it needs diagnostic tools to analyse and make algorithms for predicting SoH correctly. The Chinese found a short cut. The unnatural display of degradation and real value reduction for customers in places like Europe would be challenged legally.”
- Mehrab Vakil, a community member across EV groups in India who owns ZS EV, Tata Nexon EV, Mahindra E2O among other cars.
“Cars coming out of the showroom at less than 100% itself is concerning. With 5-10km on ODO, the car is already at 99%. Few years down the line, when companies like Cars24 and Spinny join the electric bandwagon (to buy second hand cars), they will look at SoH as a key metric. In ICE cars too, they look at engine health. Local second hand dealers will also look at SoH, which will impact ZS EV prices as well other EVs. SoH is critical to the value of the car. I usually sell cars after three years of usage, but had I purchased the ZS EV, I would have taken a huge hit.”
says Shashank Wagh, a community member across EV groups in India owning non MG electric cars.
In times to come, the insurance of the car will be linked to the SoH of the battery, if there are rising concerns of changing the battery packs, as is in the case of Tata. In an electric car, the biggest contributing factor to the IDV is the battery pack.
Ironically, Tata cars have a good battery pack in terms of degradation and they don’t have such time based SoH reduction like MG.
MG hopes that people will replace battery pack after 8 years. We know that Teslas, BYDs and even Tatas have lasted way beyond 1,00,000 kms on a single pack without much issue. What do you think is the rationale behind this logic by MG?
This information was brought to my attention by MG ZS EV Owners group on WhatsApp.
We have reached out to MG for comments and explanation on 0.0102% degradation per day. The article will be updated once we have a response.
This piece can be re-published (CC BY-NC-SA) with a line mentioning ‘This was originally published on ExpWithEVs.in’ and a link back to this page. In case of re-publishing, please alert priyansevs@gmail.com
Text, data and editing - Priyans Murarka
The SoH on LFP batteries are hard to compute.
What MG is doing here is that to err on the side of caution, they decrement the SoH value by 0.01 every day irrespective of the battery health.
But they also do a real measurement of health when the car is charged on AC from a low SoC to 100%. Personally I have seen my SoH jump from 95% to 97% and this has been replicated on many ZS EVs.
I know of folks with 60k KMs ODO and car age of 2.5 years to have 98%+ SoH because of this. So nothing to worry and I believe MG is doing the right thing here from a tech perspective.
Tesla also has a similar problem and they recently introduced an option to do deep discharge and calculate health via software. Maybe MG can do something like that
So I have emailed them regarding this before even reading this blog.
Since then no replies have been received so far.