Charging voltages are no longer limited to 5v and haven’t been for a few years. To make things worse there are different fast charging protocols and compatibility is not guaranted. The only real way to measure power throughput is an inline charge meter that can handle voltages over 5v. Modern charging can be very misleading because percentages are not always as useful as we think they are, percent is merely how far between shutoff voltage and top voltage but the curent throughput is not linear during the charge cycle. I’m not a fan of charge speeds over 15w because of how it impacts battery longevity.