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Disappointed about BMW iX DC fast charging speed

14026 Views 36 Replies 8 Participants Last post by Barkster, 11 mo ago

p=vi

Discussion Starter · Nov 11, 2020 (Edited)

BMW annnounced that the iX supports DC fast charging at up to 200 kW.

The Porsche Taycan can charge at 270kW and newer Teslas will charge at 250kW at the latest Tesla superchargers being rolled out.

Kia's upcoming EV crossover is supposed to support at least 250kW charging rate.

The Lucid Air can charge at more than 300kW. Presumably, the upcoming Lucid Gravity SUV/crossover will also charge at more than 300kW.

I don't want to buy fast charging tech that is already outdated from the moment the BMW iX is launched. Hopefully BMW is listening and makes changes as required.

1 - 20 of 37 Posts

ICS_UK

· #2 · Dec 14, 2020

I'd be happy on a 150kW charger at 40p/kwh 250kW at 70p/kwh to save a few minutes
I'm retired so the extra 5-10 minutes not a concern for me or longer on a 50kW

What is misleading is home charging at 11kW this is not going to happen for 99.9% of UK homes where it will be 7kW, so drive home with a low battery and its going to be mid morning next day before its charged.

Where as in Germany houses have 3 phase so 11kW possible

Reactions: 2

ecobimmer

· #3 · Dec 17, 2020

ICS_UK said:
I'd be happy on a 150kW charger at 40p/kwh 250kW at 70p/kwh to save a few minutes
I'm retired so the extra 5-10 minutes not a concern for me or longer on a 50kW

What is misleading is home charging at 11kW this is not going to happen for 99.9% of UK homes where it will be 7kW, so drive home with a low battery and its going to be mid morning next day before its charged.

Where as in Germany houses have 3 phase so 11kW possible

Volkswagen just started a 22kW DC Wallbox pilot project in Germany.

insideevs.com

Volkswagen Launches DC Wallbox Pilot Project In Germany

Volkswagen is launching in five German cities a new pilot project to test and gather practical experience of using new 22 kW DC wallbox.

insideevs.com

@ICS_UK what is the public charging station network like near you?

ICS_UK

· #4 · Dec 18, 2020

ecobimmer said:
Volkswagen just started a 22kW DC Wallbox pilot project in Germany.

Volkswagen Launches DC Wallbox Pilot Project In Germany

Volkswagen is launching in five German cities a new pilot project to test and gather practical experience of using new 22 kW DC wallbox.

insideevs.com

@ICS_UK what is the public charging station network like near you?

I live in Cornwall local 50kW CCS chargers thin on the ground but it is not a problem for my i3S I can drive all over Cornwall and back on a single charge. I've used the local one to me 5 miles from me when returning home with 6 miles of range left 5 miles to home. Trvelling up country more of a problem I can make Bristol, but along side the 6 Tesla chargers there is just one Ecotricity 1 output unit.
I've travelled as far as mid Wales with no range anxiety it's just not the car for long journeys hence the dramatic upgrade I previously had a 335d Touring for long journeys.

There is a 4 x 350kW station at the bottom of the M5 J28 which means for me I could drive the iX to London and back to this charge point for a top up for the last 60 miles and with 4 chargers pretty sure one would be serviceable.

XDrive

· #5 · Jun 2, 2021

2

Here are a couple of charts that BMW released of the iX's charging speed.

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XDrive

· #6 · Jun 11, 2021

2

XDrive said:
Here are a couple of charts that BMW released of the iX's charging speed.

View attachment 667 View attachment 668

Some more info about the iX's charging.

Charging at home overnight:

BMW wallbox (9.6 kW) - 475 km
Flexible fast charger (9.6 kW) - 475 km
Full charge in 11.5 hours
100 km (62 miles) range in 1 hour 41 minutes

Charging on the road for 100 km (62 miles) range:

DC Fast Charger (50 kW) - Approx. 21 minutes
DC Fast Charger (150 kW) - Approx. 9 minutes

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ICS_UK

· #7 · Jul 1, 2021

I thought the iX had a maximum AC charge rate of 11kW but looking at the small print it is 22kW for both models (BMW UK) but a real boost with so many of the UK charges AC Rapid (upto 43kw)

9) Minimum charging time at AC charging station with max. 22 kW, supply voltage 400 V, current 32 A (3-phase).

Not a massive amount about 60 miles per hour but better than the previously claimed 11kW

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NomoTesla

· #8 · Apr 18, 2022

So it looks like BMW has capped the DC charging rate in the US at 195 kW. Curious how this thread is aging. Anyone care about the car not charging at 250kW-300kW?

ICS_UK

· #9 · Apr 18, 2022

NomoTesla said:
So it looks like BMW has capped the DC charging rate in the US at 195 kW. Curious how this thread is aging. Anyone care about the car not charging at 250kW-300kW?

Its not capped they just designed it to be 195 kW I'm happy at that rate I got 5% to 75% in 34 min on my 50, surely you should stop for a rest after 250 miles of motoring

BMW have however capped the AC to 11kW it would have been far better at 22kW being what size the battery is

NomoTesla

· #10 · Apr 18, 2022

ICS_UK said:
Its not capped they just designed it to be 195 kW I'm happy at that rate I got 5% to 75% in 34 min on my 50, surely you should stop for a rest after 250 miles of motoring

Charging speed won't have much impact on taking a rest after driving 250 miles. Can still do that.

ICS_UK said:
BMW have however capped the AC to 11kW it would have been far better at 22kW being what size the battery is

That's too bad because my home EVSE can output 22kW.

hans.olbrecht

· #11 · Apr 19, 2022

Higher charging speed will increase current to the battery and the heat loss is increasing by the square of the current. Higher charging speed, could damage the battery. Cooling is key with higher charging speed.
Battery management is therefore extremely important for long-term capacity maintenance. Only Tesla and BMW have succeeded in this in the past 5 years. The choice is therefore: do you want to charge hyper-fast and a battery that only has 60 to 80% of its capacity after 5 years, or do you prefer to charge a little slower and still have a battery capacity of 90 to 95%?
I clearly have chosen for the last.
If you want to travel longer distance, take a break after 2 hours of ±20 minutes and charge your battery up tot 60 to 70% of his capacity.
To give you an idea on the time to charge 10% of the battery capacity on an iX40, I drop you the times depending on the SOC:

SOC	time
10->20	0:02:56
20->30	0:03:09
30->40	0:03:33
40->50	0:04:02
50->60	0:05:24
60->70	0:05:46
70->80	0:06:42
80->90	0:10:09

If possible, you can better stop charging at 70% an drive until 10% to start charging again.
Charging from 60% to 70% (7 kWh) takes about the same time as charging from 10% to 30% (14 kWh).
This has been calculated from charging specifications:
PS. : Only the newer 800V battery systems of some brands can charge faster, but the infrastructure there is now even less dense. But it will be the future.

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ICS_UK

· #12 · Apr 19, 2022

hans.olbrecht said:
Battery management is therefore extremely important for long-term capacity maintenance. Only Tesla and BMW have succeeded in this in the past 5 years. The choice is therefore: do you want to charge hyper-fast and a battery that only has 60 to 80% of its capacity after 5 years, or do you prefer to charge a little slower and still have a battery capacity of 90 to 95%?
I clearly have chosen for the last.

Agree with that there are quite a few i3's with 150,000 miles on the original battery that equates to around 2000 charges - I expect many Teslas as well with much higher mileages
The i3 94Ah battery was tested to 4600 full charge cycles thats around 540,000 miles

My iX 6%-70% 73kWh charge equates to 7.8 miles/min based on WLTP (195 kW max)

An Ioniq 5 which has a pretty rapid charge rate gets 11.7 m/min (225 kW max)
But considering the Ioniq has nearly 100 miles less range it would be stopping more often

hans.olbrecht

· #13 · Apr 20, 2022

ICS_UK said:
Agree with that there are quite a few i3's with 150,000 miles on the original battery that equates to around 2000 charges - I expect many Teslas as well with much higher mileages
The i3 94Ah battery was tested to 4600 full charge cycles thats around 540,000 miles

My iX 6%-70% 73kWh charge equates to 7.8 miles/min based on WLTP (195 kW max)

An Ioniq 5 which has a pretty rapid charge rate gets 11.7 m/min (225 kW max)
But considering the Ioniq has nearly 100 miles less range it would be stopping more often

The Ioniq 5 has a 800V battery system.
The i3/i8 was BMW's pilot project where they have learned a lot of competence in battery management, just as Tesla has learned a lot about battery management with the first Model S.
Both companies are pioneers in this subject.
They both have the 'fruits' about this in their new models.
The Ioniq has not this experience. So even with the 800V battery charging system (battery up to 697V, go to IONOQ forum - Ioniq 5 - Battery Overview), they should arrive at charging levels of 600 to 800 kw/h. But today they 'only' are at 225kW. It is quit conservative but for the customer, it looks like revolutionary.
Mercedes had the model B, but the number of vehicles are not at the same scale.

Reactions: 1

NomoTesla

· #14 · Apr 20, 2022

hans.olbrecht said:
The Ioniq 5 has a 800V battery system.
The i3/i8 was BMW's pilot project where they have learned a lot of competence in battery management, just as Tesla has learned a lot about battery management with the first Model S.
Both companies are pioneers in this subject.
They both have the 'fruits' about this in their new models.
The Ioniq has not this experience. So even with the 800V battery charging system (battery up to 697V, go to IONOQ forum - Ioniq 5 - Battery Overview), they should arrive at charging levels of 600 to 800 kw/h. But today they 'only' are at 225kW. It is quit conservative but for the customer, it looks like revolutionary.
Mercedes had the model B, but the number of vehicles are not at the same scale.

Simply having a 800v system doesn't, by itself, make batteries charge faster. The batteries don't care about the voltage, they care about the total current (voltage x amps). The more current you dump into a battery, the more thermal management must be done to keep the pack at the optimal temperature. That's why you'll probably never see an Ioniq 5 hit its charging potential. It, like many EVs coming from legacy manufacturers, does not have a sufficiently designed cooling system.

ICS_UK

· #15 · Apr 20, 2022

NomoTesla said:
Simply having a 800v system doesn't, by itself, make batteries charge faster. The batteries don't care about the voltage, they care about the total current (voltage x amps). The more current you dump into a battery, the more thermal management must be done to keep the pack at the optimal temperature. That's why you'll probably never see an Ioniq 5 hit its charging potential. It, like many EVs coming from legacy manufacturers, does not have a sufficiently designed cooling system.

Not quote true a 800V charging at the max A from an Ionity about 500A is 400kW so 80kWh in 12 minutes a 400V batterry at 500A would take double the time to get to 80kWh

Technically speaking the higher the voltage the better the Ioniq battery if it was 800V would be pulling half the current to get the same charge rate as a 400V battery and as you say current is the killer

NomoTesla

· #16 · Apr 20, 2022

ICS_UK said:
Not quote true a 800V charging at the max A from an Ionity about 500A is 400kW so 80kWh in 12 minutes a 400V batterry at 500A would take double the time to get to 80kWh

No, it would not, because no car can handle 400 kW. In fact, most cars cannot even handle 200-250 kW because of insufficient pack cooling.

ICS_UK said:
Technically speaking the higher the voltage the better the Ioniq battery if it was 800V would be pulling half the current to get the same charge rate as a 400V battery and as you say current is the killer

I think you are confusing Amps with current. Current is amps x voltage. An 800v car charging at 250 kW is charging with the same current as a 400v battery at 250 kW. The only difference is the 800v architecture pulls half as many amps, leading to lower resistive losses. The same current goes into the batteries, however.

Charging speed is not just a function of the maximum output of a charger. A vehicle needs to properly cool the battery to accept such a high current without damaging the battery. This is where most of the cars fall off a cliff and cannot get anywhere close to the theoretical maximum that is often quoted in internet forums.

Another aspect of charging time that is very much ignored in marketing materials is the charging curve. This makes all the difference! The peak charging level is meaningless if the car cannot sustain that level as long as possible before tapering.

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ICS_UK

· #17 · Apr 20, 2022 (Edited)

NomoTesla said:
I think you are confusing Amps with current. Current is amps x voltage. An 800v car charging at 250 kW is charging with the same current as a 400v battery at 250 kW. The only difference is the 800v architecture pulls half as many amps, leading to lower resistive losses. The same current goes into the batteries, however.

I think you need to go back to your school days kW = Amps (current) x volts / 1000

so 800V car at 250kW will draw in Amps or current same thing = 250000 / 800 = 312 A
so 400V car at 250kW will draw in Amps or current same thing = 250000 / 400 = 624 A

My 800V and 400V are generic the Ionic is well short of 800V as is the iX 400V

Sorry if in the US if you define power as current

A note on battery charging you cannot fast charge a cold battery either otiom tempertaure around 25C I think - hence the preconditioning function of Teslas and the iX
Once it gets going of course cooling vitally important

hans.olbrecht

· #18 · Apr 21, 2022

ICS_UK said:
I think you need to go back to your school days kW = Amps (current) x volts / 1000

so 800V car at 250kW will draw in Amps or current same thing = 250000 / 800 = 312 A
so 400V car at 250kW will draw in Amps or current same thing = 250000 / 400 = 624 A

My 800V and 400V are generic the Ionic is well short of 800V as is the iX 400V

Sorry if in the US if you define power as current

A note on battery charging you cannot fast charge a cold battery either otiom tempertaure around 25C I think - hence the preconditioning function of Teslas and the iX
Once it gets going of course cooling vitally important

Indeed Power (W) = Current (A) x Voltage (V)
So a 800V system will have a 312 A if charging at 250 kW and a 400V system at 624 A.
Heat losses are resistance (Ohm) x current (A)².
Higher current means more heat generation in the batterypack, thus needs more cooling.
On batterycell-level this is equal for each cell in the pack, nut all cables around needs more cooling.
That's the same raison why a iX50 can charge @200kW and the iX40 only @150kW. The batterypack of the iX50 is 50% higher then the iX40.
In Maths.
Global Current @200kW will be 4/3 of the current 150kW.
This current in a iX50 is divided to 50% more cells, so the current to each cell will 2/3 compared to the iX40.
As a result:
Current per cell will be 2/3x4/3= 8/9 of the current per cell in the iX40.
Heat generation per cell in a iX50 = 64/81 (±75%) heat generation per cell of the iX40 @max charging speed (200kW compared to 150kW. note heat generation = R x I²)
This proves that heat generation in cells are not the only parts that generates heat in a battery pack.
If this would be the case, the max charging speed would be higher for a iX50. (beside the higher current you need to pass trough the connector from your car)
It's complex because it's a combination between electric and thermic aspects.
But it is clear that a 800V system generates less heat during charging.

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Barkster

· #19 · 11 mo ago

Two days ago I went to the Ionity charging place at Cobham services on the M25 with my iX xDrive40.
I was the only car there at the beginning.
Plugged into one charger and got about 30kw/hr so moved to another charger and got about 70kw/hr, but this soon dropped off to less then 50kw/hr.
An Audi E-tron then plugged into the charger next to me and got 151kw/hr at one point - this dropped off a bit but he always had well over 100.
Then a Polestar plugged in on the other side of me and he was also getting well over 100. Both of these cars sustained rates at least twice as high as mine even though they were then over 80% charged. Why is the BMW so slow ?
I have seen 122Kw/hr once at Ionity at Jct11 of the M20 but really never seen more than 70 but most of the time less than 50.
I did have Cobham set as a charging destination on my SatNav (as I understand this pre conditions the batteries to accept a charge).
Why is the BMW charging so much slower than others ?

ICS_UK

· #20 · 11 mo ago (Edited)

Barkster said:
Two days ago I went to the Ionity charging place at Cobham services on the M25 with my iX xDrive40.
I was the only car there at the beginning.
Plugged into one charger and got about 30kw/hr so moved to another charger and got about 70kw/hr, but this soon dropped off to less then 50kw/hr.
An Audi E-tron then plugged into the charger next to me and got 151kw/hr at one point - this dropped off a bit but he always had well over 100.
Then a Polestar plugged in on the other side of me and he was also getting well over 100. Both of these cars sustained rates at least twice as high as mine even though they were then over 80% charged. Why is the BMW so slow ?
I have seen 122Kw/hr once at Ionity at Jct11 of the M20 but really never seen more than 70 but most of the time less than 50.
I did have Cobham set as a charging destination on my SatNav (as I understand this pre conditions the batteries to accept a charge).
Why is the BMW charging so much slower than others ?

I get 190 kW on my iX 50 you should be able to get 150. However if I turn up at a charger I’ve had as low as 20kW. So had you set the charger as a destination? And what was your charge state?
You can search chargers and navigate to them this preconditions the battery. Charging with anything more than 50% SOC is likely to result in a low charge rate.
You have Ionity at 26p/kWh worth going to them 2 not that far from Cobham.

sorry seen you did set Nav

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