When the battery is fully charged you should see all four (4) indicator lights lit up on the base station. If the four (4) lights are not lighting up or all four (4) lights are lit up but the battery is only lasting a short period of time it is usually one of two scenarios that are occurring.
The battery has entered a "deeply discharged" state and cannot accept a charge. This usually occurs when the headset is left active for a long period of time or has not received a charge for a long period of time.
There is a minor internal electronic glitch that is occurring that is preventing the battery from charging correctly. This is usually caused by something like a power surge.
NOTE: If SCENARIO 2 happens it can cause SCENARIO 1 to occur.
The solution to resolve BOTH Scenario 1 and Scenario 2 is a two part process.
Step 1: On the base station there is a small recessed button. Press and hold this button for one (1) second. (NOTE: On the SD Series the button is near the #4 of the mic volume dial and on the DW Series it is to the right of the six white DIP switches).
Pressing this recessed reset button provides a jolt to the battery to jump start charging. NOTE: The headset should be in the charging position on the base station when the recessed reset button is pressed.
Step 2: After the recessed reset button has been pressed the LED battery indicator lights will begin flashing indicating the boost charge process has begun. Allow the headset to sit charging for a minimum of 30 minutes.
NOTE: If the unit is connected only to USB the lights will illuminate and the unit will have some functionality when used with a computer however the USB cable does not provide enough power to correctly charge the battery and in order to have full functionality and operate correctly the unit must be connected to electrical power.