Unfortunately, like another poster said, many usb-c devices are not compliant and only charge with an "a-c" cable. This is because usb-a defaults to 5V power, but usb-c defaults to no power output without negotiation or CC resistors. If you are in a pinch, a usb c-a adapter plus a usb a-c cable does work. In my experience these use the cheapest possible usb-c connectors that don't expose the CC pins, so to fix them, you need to remove the connector and install a new one. See [3] for power only and [4] for power+data.
Anyway, I always like to share 3 cheap products for anyone interested in upgrading devices to usb-c charging or connectivity. Since these are available from many aliexpress sellers but the actual listings come and go I will share search terms which hopefully work 1+ years from now.
- usb-c charging PCB for a lithium ion cell[2]
- usb-c connector with integrated 5.1kohm resistors, to easily use usb-c for 5V power without data.[3]
- usb-c connector with just enough pins for adding CC resistors and connecting to power and usb 2 data lines in an existing product, but without all the additional pins for usb3 and thunderbolt (because this makes it very difficult for a hobbyist to solder it in place without bridging pins). Unfortunately I don't know of a product with CC resistors + power pins + data pins so you do have to add CC resistors yourself.[4]
- small PCB with a chip to negotiate more than 5V (9V, 12V, 15V, 20V). Some of these offer fixed voltage and some are configurable.[5]
[1] https://en.wikipedia.org/wiki/Apple_Wireless_Keyboard#/media...
[2] "Ultra-mini Type-C USB Charger Module DC 5V 1A Charging Board"
[3] "USB 3.1 Waterproof Type-C Connector 16PIN 5A Female Socket Double 5.1K Resistor Support Charging And Discharging"
[4] "Micro USB-3.1 SMD 16P type-c Female Connector Socket"
[5] "usb-c decoy module"