Internal backup battery

To test the battery, turn the unit on for a few minutes then turn the unit off and wait 10 minutes before measuring the voltage at the internal battery contacts, if the volgate is below 2 VDC then the battery is not holding and should be replaced.

The backup battery is required to maintain the GPS location values while the unit is turned off, with a bad battery each time the unit is turned on the satellite acquisition takes five to ten minutes and with a good backup battery the acquisition takes around 30 seconds if you have not moved from the last location.