Automated USB device efect

Hi there,

I've been googling around, but I could not find the solution for this puzzle. appreciate any help.

I bought a GPS tagger, and it charges by USB. However, it does not have an overcharging sensor, which means it HAS to be unplugged after 1 hour or so.

Is there any software/app to automate this taks? Basically, every time my Os identifies that this particular hardware is connected it programmes to eject it one hour later, this is what I need.

thanks a million,

fabrolino