52kw ID.4 Charging curve

Does anyone know where to find a charging curve for an ID.4 with a 52kw battery. I can see the bigger battery option on Fastneds website, but nothing for the smaller battery,

I keep trying to get more than 65kw but have failed, more often than not I get 54kw, starting with battery percentages from anything from 5-20% up to charges starting with 40 or 50%, I get the same result of 54kw per hour petering out to around 30kw once the charge gets into the 70% range. That's after a run (or not) to warm the battery.

Just wondering (assuming it is) if this is normal for the smaller battery and it charges at quite a lot slower rate than the larger battery, and why that might be.