I do not fast charge often, and have never paid attention to how fast it is, but decided to today. I was at 56%. I had preconditioned the battery. Air temps 70F. I was at an Electrify America 350 kW CCS charger. According to the published charging curve this should be a 14 minute charge, and should start around 135 kW and end at 100 kW.

It took 22 minutes. Max charge was 90 kW, ended at 78 kW. In theory, this car should be able to go from 40% to 80% in 22 minutes. This was sad to see to say the very least.

 

Some people at work, some of whom have Lyrics, said that this is not unexpected. Mostly because the battery probably was NOT at proper temperature. I had about a 20 minute highway drive and I did choose to pre-condition on the screen about 5 minutes out from the charger. Thing is the car immediately told me it was ready to charge. People are saying "technically true, the car can charge at any point, but is hardly an indication that the battery is actually at optimal temperature". So my battery probably was not as warm as it should have been to get full charging. And not much to do different to reliably make this better.

Sigh.

 

DCFC speed definitely leaves a lot to be desired, especially when compared to the new wave of 800V EVs. On top of that, Ulitim EVs are sensitive to battery temperature and as a result, the charging speed can vary greatly.

From what you described, 90kW max at 70F ambient with preconditioning sounds more like a station issue. If it is battery pack related, usually you still see high charging rate briefly, then BECM quickly ramps down the speed.

How long did you precondition the battery? For my car with the latest BECM software, I usually precondition the battery for 20-30 minutes to ensure consistent charging speed. 70F ambient temperature does not guarantee that the battery pack will be in the right window with a 10-minute preconditioning.

On my car, the charging speed is relatively consistent for the first 50kW. Beyond that it is a bit of a draw of luck. Therefore, charging from 20%-80% is more trustworthy than starting from 10% range.

For reference, best case scenario, my car can take 60kW in a little over 25 minutes. I feel 20-80% in ~30 minutes is something I can rely on. 10-80% in 35-37 minutes is possible, but not something the car can repeatedly do, especially not in the afternoon.

 

The total drive was about 15 miles long. I selected "prepare for fast charging" about 5 miles away. It nearly immediately said I was ready to charge. (Technically true, but certainly not optimal). It's beginning to sound like that isn't long enough and the battery probably wasn't optimally warm.

 

Wondering how I know if I have all the latest software. I did get the recall installed. I am on AA14. I have no idea if I have the latest BECM software.

 

Even though, like others, my ZDX has always indicated an immediate readiness to fast charge as soon as I hit the pre-condition button, it's my understanding that it could take 30 minutes or longer depending on the temp of the battery. In cold weather it must be warmed, when it's been driven hard it must be cooled. I understand that when it's cold one can warm it quickly by surging on the accelerator, causing the electrons to get excited. Good for a cold morning fast charge experience.
Additionally, the few times I've fast charged I have seen very unimpressive results. Without documenting the details, my impression was that charging has never lived up to the claim of 190 kW DC fast charging capability as stated on the window sticker! Even at 400 kW dispensers with no one else plugged in I might have seen 120 kW for a short period with a drop off into the 90's or 80's.
Still love the car, however!
John

 

No way to tell without an OBD-II scanner. However, there are only two or three SPS2 updates since the OTA one. These updates have similar charging performance, maybe prioritize slightly towards the 20-40% window than the original software.

The biggest difference is that the radiator fan and compressor are less noisy under heavy load like a deep DCFC session. If I remember correctly, the car can sound like a jet engine with the original software and OTA update. In comparison, the car sounds more like a powerful, whining fan with newer software. So you can infer the BECM software from the cooling system noise.