How long is the battery life of a GPS tracker, when used to detect motion only?

[patrickdiviacco]

I was looking at GPS Trackers such as Spark Nano 4.0. I wanted to apply one of these devices inside my boat to exclusively use it for motion detection in case of theft.

The battery life of this device is of 2 weeks, for accurate tracking in movement. But I can't find how long it last for the motion detection task.

I'm planning to deactivate it then, when I'm sailing to save the battery.

thanks