Smart chargers aren’t always that smart.
I purchased a Hedbox RP-DC50 for my NPF batteries and thought that instead of having the same type of battery in both slots I would get a plate for my Nikon D850 batteries. Putting one of the D850 batteries in the charger and leaving it for a bit, I returned to the charger to tell me the battery was now at 100%.

Except this was a lie. Putting the battery into the camera showed that it wasn’t at 100% but 10% lower.

Charging the battery with the charger that came with the camera gave me a full reading.

Now I’m wondering if the RP-DC50 is charging my NPF batteries correctly. Maybe there is something to be said for dumb chargers.