RE: Do your own JR 8103 Lithium battery replace?
If you are quick enough in removing the old and soldering in the new, then it wont lose its settings. If you take too long, then the voltage dies off and the internal calibration settings are gone. Once this happens, you have an uncalibrated transmitter on your hands.
From experience, althought the battery life is nominally 5 years ( ish ) I have replaced lithiums that still have sufficient voltage after 10 years.
What is the actual lithium voltage at the moment ??