I know this for the
Mavic 2 and think it's the same for the mini.
You can NOT fast charge. The battery management system on the battery controls the charge rate. There are charges that advertise as "fast charge" and either they are just trying to provide false marketing or they are doing parallel charging (charging 2 or more batteries at the same time).
Fast charging is when you charge at > 1C rate. 1C = 1 x the capacity of the battery. If the battery is a 1100mah battery then a charge of 1.1Amps would be 1C and take about an our (for a full charge). If you were able to charge at say, 2.2Amps, that would be 2C and considered a fast charge.
So, don't fall for the "fast charge" hype. DJI batteries control the charge and only let you charge at a 1C rating which takes 60+ minutes to fully charge.