Current drop relay for coffee grinder auto off

[TyMonk]

I’m looking make a motor adapter for my hand coffee grinder. 
Obviously I know there’s electric grinders already but I fancy the project and like the idea of one grinder for both.
I’ve sourced a good motor and I’m pretty happy with the assembly but I would like to have an auto shut off feature. 
While under load  you can hear the motor putting in work so I’m sure there’s a significant current spike. 
Then once all the beans have passed through the grinder the motor returns to it’s no load sound/draw. 
My question is, is there a relay out there that I can set to switch off once the motors current draw drops? 
the motor is a 3.6v hand screwdriver powered off of what looks like a single 18650 lithium cell listed at 2Ah 
I have a roundabout knowledge of electronics but nothing all that impressive. 
Any help would be appreciated. 

Kind Regards 

Tyler 

[HarryA]

I gather you are looking for a circuit like this one. Do you have any idea what the currents are? Perhaps one could key off the change in voltage at the battery; low voltage turns a transistor on to  power a relay.

Edited: The circuit needs a momentarily open push button switch  between the battery and the relay coil to switch if off.