I want to build my own coffee grinder using high torque motor (12 volts). Is there any available “driver” that can convert output from a single 18650 battery into 12 volts?
I want this grinder to be portable so I can use it without plug it into wall socket.
Sure, you just need a boost converter that can handle the watts necessary (and a 18650 that can handle the current). Look around on eBay. Depending on the requirements of the motor it may be easier/smaller to just run three 18650’s in series.
A “buck” driver is used to reduce the voltage, so that the output voltage is less than the input voltage. In this case, your input voltage is 3.7v (from the 18650) and you are seeking 12v output voltage. A buck driver will not work. You need a “boost” driver.