Max range dropping at 100% charge

[Paulnz5]

Hello. We have been very happy with our 2021 MG ZS EV we bought just under 12 months ago.
After several months ownership I remember commenting how the maximum range wasn’t decreasing (seemed to be sitting about 261/262km). However over the last 6 or so weeks it’s range at 100% charge has dropped to 241 km (originally it was about 265km).
We have traveled 16000km of which 97% would have been charged on the 3 point plug granny charger. We mostly try to keep it in the 20-80% range, however it is charged up to 100% once a week for an intercity round trip.
Thoughts and how does this compare to others.
Thank you for any responses.

 

[Coulomb]

My guess is that a lot of it is due to being winter in the southern hemisphere.

I didn't reset my trip meters for a long time, and that left the estimated range after a full charge at the 273km point for about a year. Just recently, it came down a couple of kilometres. I then reset both meters to see if that changed it, but it didn't. Now my range at 85% SoC (per the car, about 80% SoC per OBD2) is different to the usual numbers. I don't know if that's because of the meter resets, or because I might be dipping below 100% SoH. My car is 14 months old, only 7000 km.

I recently saw 100% SoH on the unofficial Thai app, but I haven't verified that with another app. My guess is that I'm at say 99.7% SoH, which rounds to 100%, but it's far enough below 100% that my figures are now starting to fall below what they were at 100%. Remember that SoH falls quickly in the first year, then more slowly after that, and the rapid fall is masked by pegging the reported SoH at 100% for most of that.

So my figures won't be much help to compare with yours, as I don't have enough age or kilometres to get much past the 100% SoH cap.

I charge to 85% (per the car) most of the time, going to 100% once a month or before a long trip. Long trips have been very rare, unfortunately. No fault of the car.

 

[ChrisR]

I've had a similar drop recently. For the first 15 months the maximum range stayed at 263km when I did a balance charge roughly once a month (regular charging is normally to 80%). But the last two full charges have gone down to 250km. I also hadn't reset the trip meter for a while and wondered if that was the cause or the colder weather (though still rarely below 20C during the day).

I've still only done a bit over 12,000km so I'm a little surprised at 95% SOH but I'll keep checking after winter.

 

[hmadsen]

The range is affected by a lot of things.

• Speed
• Temperature
• Driving style

If i reset the trip meter and do a "Motorway only" run, the range when fully charged will be less, than if i do 200 miles at city and country road speeds.

The range is calculated, based on the consumption in the last XXX miles, so if it is cold and you do a lot of motorway driving, the range will be showing as a LOT less, than if you do country road driving in the summer when it's 20c+ all of the time.

 

[Coulomb]

The range is affected by a lot of things.

Sure. But when the two trip meters are reset, the BMS seems to throw away all history and give an estimated range based solely on its SoH (State of Health, estimated battery total capacity). That's why this figure can be solidly 263 km for many months after manufacture, as the SoH is reported as exactly 100.0% for that period.

So drivers get used to that predictable number, and wonder what it means when it eventually starts to go down.

 

[hmadsen]

Sure. But when the two trip meters are reset, the BMS seems to throw away all history and give an estimated range based solely on its SoH (State of Health, estimated battery total capacity). That's why this figure can be solidly 263 km for many months after manufacture, as the SoH is reported as exactly 100.0% for that period.

So drivers get used to that predictable number, and wonder what it means when it eventually starts to go down.

Aah i see.

I have not reset mine yet (The "lower" one) so i did not know that.