USB CABLES
If you want to use a fast-charger - the type of USB cable that you use matters!
When fast-charging, your charger communicates with a chip in the *cable* to check that the cable can handle the higher current.
This process is invisible to the user - so a non-compliant cable will result in slow-charging, even if Z-RAY and your charger want to fast charge.
Look for a cable that's sold as USB PD (Power Delivery) aware/compliant, or proprietary fast-charging standards.
Think Radio can't check all possible combinations of chargers and cables, and we've even found that premium brands are not always compliant.