[hans.olbrecht]

I was triggered by a post of brownbottle to do some research on DC charging stations. And I found some information, dealers will not tell you but it is worth to know.

A 150kW/175kW DC charger is designed to provide a maximum power output of 150kW/175kW, but this does not mean that you will always receive 150kW of power when you use it to charge your BMW iX. There are several reasons why you may not get the full 150kW output:

• EV battery state of charge: The state of charge (SOC) of your EV battery will affect the charging speed. If your battery is low on charge, it will accept a higher charging rate, which means you may receive close to the maximum power output from the charger. However, if your battery is already partially charged, the charging rate will slow down to avoid damaging the battery.
  For iX following charging curves are available:
  
  
  
  
  
• Battery temperature: Charging a battery generates heat, and if the battery temperature is too high, the charging rate will be reduced to prevent overheating. Conversely, if the battery is too cold, the charging rate will be limited to avoid damage to the battery.
  For iX: don’t forget to select the charging point as destiny of your navigation system. The temperature of the batteries will be preconditioned to let it possible to absorb the 150kW.
• Charging cable and connector limitations: The charging cable and connector used to connect your EV to the charger also have a maximum power rating. If the cable or connector is not rated for 150kW, the charging rate will be limited to the maximum rating of the cable or connector.
  For iX: exactly this is the weak point.
  Normal charging cables are limited to 400A or less. (Voltage is normally no problem as they are almost all designed up to 1000V). Water cooled cables are limited to 500A.
  Now the iX has a 94p2s (iX40) or 94p3s (iX50 and iX60) battery configuration. This results in a battery Voltage of 94 x 3.5V = 329V. When charging at 400A, it will result in an absorption of 329x400= 132kW. For a cable supporting 375A, this results in 123 kW. If the charger is equipped with a water cooled cable the same calculation will deliver 165 kW and the charging power will be limited by the car to 150 kW.
  For the same reason, the iX50 charge in the beginning is limited to 329x500=165kW. When battery Voltage is increasing when the SOC is increasing, power will increase by 500A up to 4.14V per cell (just below the 4.20 limitation for NCM811 batteries). Switching to 400A by the car will reduce charging power to 156kW.
  Remark: The BMW i4 will not have this problem, since his battery configuration Is a 108p3s which gives a battery voltage of 108x3.5=378V resulting in a power charge of 142kW for a 375A cable and a 151kW for a 400A cable.
• Charger limitations: While a 150kW charger is designed to provide a maximum power output of 150kW, it may not always be able to do so. The actual power output may be limited by factors such as the quality of the electrical supply, the temperature of the charger, and the number of vehicles charging at the same time.
  This is logical from the point of view of High voltage electronics.

In summary, while a 150kW DC charger is capable of providing a maximum power output of 150kW, the actual power output you receive will depend on several factors, including the state of charge and temperature of your EV battery, the quality of the charging cable and connector, and the limitations of the charger itself.

Remark: All 300/350kW chargers I know are equipped with water cooled cables.

 

[electric_journey]

@hans.olbrecht Cool. Thanks for sharing. I suspect many iX drivers would not care or have the interest in all these technical details. They will just want a simple answer as to why the car doesn't charge as quickly as "marketed" on the BMW website. Unfortunately, there are far too many technical things that an EV driver needs to be aware of that you don't have to think about when refuelling an ICE car.

It's not like someone filling up with petrol has to consider, how much fuel is left in the tank when filling up, or how many other cars are filling up at the same time or the ambient air temperature and whether their "engine" has been preconditioned or the quality of the pipe supplying the petrol?

Either they need "market" EVs with all of these caveats much more clearly upfront to manage expectations or work on technical fixes that mean someone recharging an EV at a public charger doesn't have to think any more than when they used to fill up with petrol or diesel.

 

[hans.olbrecht]

@hans.olbrecht Cool. Thanks for sharing. I suspect many iX drivers would not care or have the interest in all these technical details. They will just want a simple answer as to why the car doesn't charge as quickly as "marketed" on the BMW website. Unfortunately, there are far too many technical things that an EV driver needs to be aware of that you don't have to think about when refuelling an ICE car.

It's not like someone filling up with petrol has to consider, how much fuel is left in the tank when filling up, or how many other cars are filling up at the same time or the ambient air temperature and whether their "engine" has been preconditioned or the quality of the pipe supplying the petrol?

Either they need "market" EVs with all of these caveats much more clearly upfront to manage expectations or work on technical fixes that mean someone recharging an EV at a public charger doesn't have to think any more than when they used to fill up with petrol or diesel.

I fully agree.
Moreover, in practice there is not such a big difference.
Charging at 150 kW is in any case only limited between an SOC of 10 to 30%.
The 'lost' time is barely 1 minute (7 and a half minutes instead of 6 and a half minutes to get from 10% to 30%).
Still, it keeps users busy and no one can give them an explanation.
That's why I wrote this article (because in a way we are all ambassadors for this new mobility) and perhaps the best advice to other users:
"It depends on the charging installation. Take another or accept the extra minute."

 

[Rich-UK]

I fully agree.
Moreover, in practice there is not such a big difference.
Charging at 150 kW is in any case only limited between an SOC of 10 to 30%.
The 'lost' time is barely 1 minute (7 and a half minutes instead of 6 and a half minutes to get from 10% to 30%).
Still, it keeps users busy and no one can give them an explanation.
That's why I wrote this article (because in a way we are all ambassadors for this new mobility) and perhaps the best advice to other users:
"It depends on the charging installation. Take another or accept the extra minute."

Wish I'd seen this before choosing between IX50 and IX40! We chose the IX40 and charging speeds have been frustrating to say the least. These graphs now explain why, especially when we have been topping up from say 50% battery, so even in perfect conditions (highly unlikely), we would be lucky to get 100kwh at 50% dropping down to 50kwh at 80%. The IX50 appears to perform way better, achieving maximum charging rate up to 40% battery and achieving double the charging speed of the IX40 at 80% at nearly 100kwh. IX50 owners probably do not need to charge up to 100% due to increased 100 mile range whereas IX40 owners are more likely to need a full charge en-route. For example, we do a regular 200 mile motorway journey. Range can drop as low as 160 miles in cold weather so we normally top up around at around 50% to get us to our destination.

 

[NomoTesla]

You people are spoiled! My 2013 Model S only hit 115 kW for the first 5% and throttled down thereafter to 20 kW at 90% SOC. The vast majority of the charging curve was spent at around 70 kW. With that said, I still managed multiple interstate trips and the car was a pleasure to use for long-distance travel for almost 10 years.