How long does the battery last on the Personal Tracking Devices?

We currently have a few personal devices available which suit different purposes

TMT250 which is small, 2G and gives 1-2 days of use between charges

GL320MG which is slightly bigger and 4G capable, which lasts 1-2 weeks

Pebble Tracker which is a small and simple 2G device which lasts 5-7 days

All can be easily recharged