Interesting results.Benjiturp wrote: ↑Mon Mar 11, 2024 7:56 pm Hi all,
So today I did a full run from 100% to see what the battery degradation might be, and was pretty interesting seeing how energy was used over time. For background, July 2022 car with 25,500 miles, I believe 2.4 software, 2 of us in the car, 8°C on average, running in Eco mode and B on the drive selector. Used very little heating if any at all.
I covered 178 miles in total from the Wrexham area to Anglesey mostly along dual carriage way mostly cruising at 65mph with cruise control, using 93% of the battery. Efficiency was 4.0 at the end but flitting between that and 3.9. 19 miles were remaining on the range indicator, so total range for the battery is 192-198 miles.
This calculates that around 12% of the battery capacity has been lost when calculating against 58kWh, so a fair chunk which is a bit concerning. But considering the lack of decimal places for % and kWh this isn't completely accurate and if the consumption figure is generous then just a 0.1 change can make a big be difference to calculated degradation (e.g., 3.8 kWh would suggest 10% degradation).
In terms of discharge behaviour, I lost 2% of charge by the time I got to the end of my road, and 3% total loss after 3 miles. I recorded miles covered at 10% battery intervals.
16 miles @ 90%
37 miles @ 80%
55 miles @ 70%
72 miles @ 60%
91 miles @ 50%
109 miles @ 40%
122 miles @ 30%
141 miles @ 20%
170 miles @ 10%
179 miles @ 7% (19 miles remaining on the guage)
So a few thoughts on this.
- Deg appears quite high but then I don't know how the battery was used by the previous owner.
- With degradation in mind, is this acceptable as I have the car on a good monthly price (0% APR)?
- Energy loss in the first 3 miles is high suggesting the battery heater was running, or something else (no cabin heating at this time).
- Does anyone know whether the efficiency read out is accurate or similar to ICE cars which tend to over-estimate, as my efficiency today seemed a bit too good for the conditions.
I tend to believe the consumption data in the car. Some (including me) found that it improved a bit post 3.0 software update, but I do get some more indicated degradation if I do a calculation like yours now than I used to. My actual range hasn't reduced noticeably so I don't worry too much about it.
It's worth remembering that you can't easily measure the SoC in a battery like you can the level in a tank - indeed the BMS' estimate of energy consumption is one of the inputs to its estimate of battery %, rather than vice versa.
Also relevant to consumption of course are charging losses. If using a 7kw charger, your consumption from a home charger will be about 8-10% higher than consumption of the car while it's running (at least that's what I see). Losses are higher on a granny or if you run at a lower AC power, but lower if using a rapid.
It's worth bearing in mind that when new the car would not have had a full 58kwh available from 100% to 0%, but more likely 55-56kwh. This brings down your estimated degradation a bit.
I think your degradation is a little worse than ours (a January 2022 Family with 22000 miles) but not drastically so.
It is surprising that the car lost 3% inside the first 3 miles and that's not normal. High energy use due to the battery heater isn't a plausible reason in the current UK climate if it's a 2022 car on 2.4. My guess is that you have a problem with one or more of your battery cells being difficult for the BMS to regulate that might well lead to them being identified for replacement when you get the car updated to 3.2. When the recall for this battery cell issue was first published it was said that one of the observable symptoms could be sudden drops in % at the top or bottom end of the SoC range. If so, the positive aspect is that the recall might improve your car's battery performance, the negative is it means you'd have to send the car off to be fixed (you'd get a courtesy car). However I would emphasise this is only an informed guess and you can't know without getting the update and battery check recalls done.