The BIOS will reset to its default settings if the back up battery (CR2032) falls to 3.00 volts or below. The battery is NOT rechargeable. A new battery will read around 3.32 volts and will on average last for 4 - 5 years. However, if the MC is not powered frequently, then the battery will be providing power to the BIOS chip more often and its life expectancy will deteriorate quicker. The ambient temperature of the battery is also a factor in its life expectancy.
Continuous cold conditions (below freezing) will shorten the life. Cold conditions (e.g when being trucked overnight) will also drop the output voltage, which could take the battery below 3.00 volts and cause the BIOS to reset. However, when the battery warms up the voltage will then return to near its original level, but the BIOS will have already reset.
The BIOS battery voltages can be read from the diagnostics pages of the individual consoles. Click on the MC in the diagnostics page (GUI as well for XL8). A diagnostics box for the MC (GUI as well on XL8) will open - scroll down to VBatt. The battery can also be measured while still installed, but with the mains power off. This will give a rough idea of the voltage. If the battery is still good, i.e. 3.01 volts and above, then the BIOS should not have reset. However changing the battery with the power off, will reset the BIOS, so it would be advised to replace the battery with the motherboard powered. It is recommended that changing the battery with the motherboard powered is only performed by a Midas Certified Technician who will take all the necessary electronic precautions to do the job safely.
If the battery is found to be 3.00 volts or below, then it is more than likely that the BIOS has reset, and then the battery can be changed with the power switched off. We do however still recommend that this is performed by a Midas Certified Technician. The new battery much be inserted the same way round as the one that was removed.
For the relevant BIOS settings and how to access the BIOS, you will need to submit a ticket through the Care Portal, where we will be able to help you further.
Issues that may be seen if the BIOS settings are reset, are that the time stamps in the logs will always begin at the same date and time for every power, thus overwriting the logs from the previous power up, and the MC may not start - this is mainly on XL8 and PRO3, PRO6, PRO9 that used the Kontron motherboards