Long v Short Journeys and Battery Heating

[sidehaas]

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.

Interesting results.
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.

[Benjiturp]

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.

Interesting results.
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.

Thanks for your thoughts and feedback on this, very helpful. Interesting that batteries aren't necessarily at 58kWh considering they're 62kWh gross with VW claiming the 58 as useable. Guess these things are never clear cut and the key thing is how I myself treat charging and driving to get the range I need, which today was actually ok, and more pleased with the efficiency of 4.0 miles/kWh .

The recalls you mention, I had heard of the tyre issue before, but forgot about that. Didn't know about the battery cell issue, but interestingly I cancelled an order a couple of months ago on a second hand Family spec as VW (the seller) told me the day before delivery that cell 12 needed replacing (few months wait for the part from Russia). My car has Goodyears fitted with 4mm left, so I suspect these are the originals.

The car is booked in for a 3.2 update in April, and they want the car for 2 days which seems long, so I suspect they'll be doing these checks but I'll call them to query and ensure it's on their list.

Hopefully I'll get new tyres out of it and confidence at least that the battery is ok.

[sidehaas]

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.

Interesting results.
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.

Thanks for your thoughts and feedback on this, very helpful. Interesting that batteries aren't necessarily at 58kWh considering they're 62kWh gross with VW claiming the 58 as useable. Guess these things are never clear cut and the key thing is how I myself treat charging and driving to get the range I need, which today was actually ok, and more pleased with the efficiency of 4.0 miles/kWh .

The recalls you mention, I had heard of the tyre issue before, but forgot about that. Didn't know about the battery cell issue, but interestingly I cancelled an order a couple of months ago on a second hand Family spec as VW (the seller) told me the day before delivery that cell 12 needed replacing (few months wait for the part from Russia). My car has Goodyears fitted with 4mm left, so I suspect these are the originals.

The car is booked in for a 3.2 update in April, and they want the car for 2 days which seems long, so I suspect they'll be doing these checks but I'll call them to query and ensure it's on their list.

Hopefully I'll get new tyres out of it and confidence at least that the battery is ok.

The battery check recall is always done together with the 3.2 update.
This website gives up to date info about recalls outstanding on your car if you input the VIN (there isn't a UK version):

https://www.dieteren.be/en/recall/?fbcl ... K2SbuAtNeU

We had a battery cell replaced recently under the recall. It was a hassle because of having to get the hire car, collect our car afterwards etc. But the process does at least seem to be getting faster (in the past some people have waited months due to supply chain problems, ours took 5 weeks which included clearing a backlog of a few cars before ours). So I try to look on the positive side of it ie we have a new battery module despite not having noticed any real problems.

[sidehaas]

Can I ask, by the way, where/how you got the 0% APR on a used car? I'm looking at slightly bigger ones like ID4 size to replace our remaining ICE and it would be very helpful!
Thanks

[Scratch]

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.

Has the car got a heat pump fitted?

[Benjiturp]

Interesting results.
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.

Thanks for your thoughts and feedback on this, very helpful. Interesting that batteries aren't necessarily at 58kWh considering they're 62kWh gross with VW claiming the 58 as useable. Guess these things are never clear cut and the key thing is how I myself treat charging and driving to get the range I need, which today was actually ok, and more pleased with the efficiency of 4.0 miles/kWh .

The recalls you mention, I had heard of the tyre issue before, but forgot about that. Didn't know about the battery cell issue, but interestingly I cancelled an order a couple of months ago on a second hand Family spec as VW (the seller) told me the day before delivery that cell 12 needed replacing (few months wait for the part from Russia). My car has Goodyears fitted with 4mm left, so I suspect these are the originals.

The car is booked in for a 3.2 update in April, and they want the car for 2 days which seems long, so I suspect they'll be doing these checks but I'll call them to query and ensure it's on their list.

Hopefully I'll get new tyres out of it and confidence at least that the battery is ok.

The battery check recall is always done together with the 3.2 update.
This website gives up to date info about recalls outstanding on your car if you input the VIN (there isn't a UK version):

https://www.dieteren.be/en/recall/?fbcl ... K2SbuAtNeU

We had a battery cell replaced recently under the recall. It was a hassle because of having to get the hire car, collect our car afterwards etc. But the process does at least seem to be getting faster (in the past some people have waited months due to supply chain problems, ours took 5 weeks which included clearing a backlog of a few cars before ours). So I try to look on the positive side of it ie we have a new battery module despite not having noticed any real problems.

I've checked with my local VW and yes the battery is getting checked out, plus I've added a service (might at well since it's due soon). Interestingly the tyre replacement isn't on their system to look at (I have the Goodyears) but I might push them on it anyway.

As for the 0% APR, I got the car through car supermarket.com. I had queried about the car before the 0% was applied. The day I was going to agree to purchase, the 0% finance was advertised on the car but the car had an increased retail price. Either way, with extended warranty and paint/interior protection the monthly cost is £290 with £1000 down which is pretty good (4 years, 10k miles/yr). I've not seen any others with 0% so far.

[Benjiturp]

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.

Has the car got a heat pump fitted?

No heat pump as far as I'm aware

[Midgex]

...
, I lost 2% of charge by the time I got to the end of my road, and 3% total loss after 3 miles. ...

- Energy loss in the first 3 miles is high suggesting the battery heater was running, or something else (no cabin heating at this time).

Without being in any way expert on this, I'd be inclined to think that a rapid change at the extreme is more about the measurement being refined than about excessive use of power.

If we were designing the monitoring system, we would want the car to stop trying to put more energy into the battery when it got to notional full capacity; and we would be concerned that the energy/range indication was reliable around the lower middle range, say 50-20%, since that is when decisions to charge or not charge en route are likely to be more critical; and then to underestimate slightly, or not overestimate at all, the range in the lowest range. Being 4 miles from home with 5 miles range is one thing, 5 miles away with 4 miles range is quite another.

Numbers as guesses.
Obviously better to be 4 miles from home with 44 miles range, but things happen.

[sidehaas]

...
, I lost 2% of charge by the time I got to the end of my road, and 3% total loss after 3 miles. ...

- Energy loss in the first 3 miles is high suggesting the battery heater was running, or something else (no cabin heating at this time).

Without being in any way expert on this, I'd be inclined to think that a rapid change at the extreme is more about the measurement being refined than about excessive use of power.

If we were designing the monitoring system, we would want the car to stop trying to put more energy into the battery when it got to notional full capacity; and we would be concerned that the energy/range indication was reliable around the lower middle range, say 50-20%, since that is when decisions to charge or not charge en route are likely to be more critical; and then to underestimate slightly, or not overestimate at all, the range in the lowest range. Being 4 miles from home with 5 miles range is one thing, 5 miles away with 4 miles range is quite another.

Numbers as guesses.
Obviously better to be 4 miles from home with 44 miles range, but things happen.

It stops charging the moment the voltage across any single cell teaches the maximum predefined limit (I think it's around 4.2V). There is some margin from that limit to the actual maximum voltage the cells should be at when the battery is truly full, and all the other cells are at slightly lower voltage because there is variation between them all. That's what creates the top buffer effectively.
That's what provides