All my Tx batteries show a voltage over 11 volts when fresh off the charger. If you are reading 10.5 immediately after charging the battery may need replacing.

The nice thing is that unlike a Rx/Servos a Tx puts a constant load on the battery. You may want to charge the battery and leave it on for an hour to see how it holds up (well away from anywhere you may interfere with anyone else). If in doubt, replace.

Terry