Your Joy Drive does not get power from your phone or tablet, it uses the battery built into the device.
When you plug the Joy Drive into some newer versions of Android, sometimes you will receive a message saying “Toolkit Mobile is using battery”
While it may appear that the Joy Drive is getting power from your phone according to this message, that is not the case. The Joy Drive uses a small amount of power to help it detect when a phone is plugged in, and that is what the phone is notifying you of.