You may not notice this happening but the control boxes that you use constantly are frequently updated by re-programming their associated software (Firmware FW)  This is what has changed since the Caddiehoe Chase usage.

The batteries eventually discharge on these units although they last for up to 5 to 8 years in practice. We regularly check the battery state of every unit in order to anticipate failures. This file here  gives the results of the latest check.

SPORTident BSx7/8 firmware 656 release notes
October, 2016
SPORTident GmbH • www.sportident.com • [email protected] • Arnstadt • Germany 3
Changes in the firmware 656 since version 649
Firmware version 656 introduces performance and stability improvements and fixes
known issues. No new features have been added since firmware 649.
Improvements
 Optimized power consumption, enhanced battery consumption counter accuracy
 Improved SIAC battery test display message:
o Station will show “WARN” (warning) for voltages ≤ 2,71 Volts
o Station will show “FAIL” (failure) for voltages ≤ 2,44 Volts
 Field detection improved for waking up the station from sleep mode
Fixed issues
 Fixed SIAC readout in legacy protocol mode