Maybe the battery is fully charged and the led's turn off when its full?

Did you do the power conditioning step with the PTX3? Not sure if you even need to but worth looking in to. This is from the TPMC-3X manual.

Battery Calibration
For optimum performance after shipping or any time the unit’s power has been off for an extended period of time, Crestron recommends the following procedure be performed:
1. Place the unit on its docking station/charger and connect AC power.
2. Allow the unit to charge completely. (The green LED should be steady on for 15 minutes.)
3. Remove panel from the docking station/charger.
4. From the main setup screen, touch Diagnostics, then touch Battery Diags to go to the Battery Diagnostics screen. Touch Recondition Battery, then touch YES, Recondition Battery to confirm. (Refer to “Configuring the Touchpanel” which starts on page 15.)
5. Wait for the unit to shut off. This takes approximately five hours. Leave the unit off the dock the entire time. During this operation, the Battery Reconditioning screen shown on page 25 will be displayed until the unit shuts off.
6. Place the unit back on the docking station and allow it to charge completely.
7. Unit is now ready for normal operation.


Optimizing Battery Life
In order to maximize battery life, use the following settings:
1. From the main setup screen, touch Standby Setup to enter the Standby Timeouts screen (refer to “Standby Setup” on page 22). Use an Undocked Standby setting of 30 and an Undocked Power Off setting of 45.
2. From the main setup screen, touch LCD Settings to enter the Display Settings screen (refer to “LCD Settings” on page 27). Use an Undocked Brightness setting of 50.
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