I charge my batteries in the charging station of the Fly More kit and use the USB-C charger on my laptop. This has the Power Delivery standard and charging the 3 batteries is quite fast. If I only use the charger of my mobile, this also works, but much slower. The LEDs on the charging station also flash more slowly to indicate that Power Delivery is not active.

what is "so long"?
But apart from that, the charger must of course be able to deliver the necessary power.
With a reasonable 35W (or more, of course) charger, it's quite fast.