The CPU cards in the Omega and Median frames use the following non-charging Lithium batteries depending on the CPU card version: The battery is used to backup system data like config data and online data.

Current CPU card part # 710746Z (July 2008 to present)
This version of the CPU card is fitted with a battery holder and allows for field replacement of the battery, the part # for this version of the battery is Clear-Com part # 400068Z, Renata CR2477N.

CPU card part # 710746Z (up to June/July 2008)
This version of the CPU card is fitted with a battery with solder tabs and is directly soldered to the CPU pcb. This version of the battery is Clear-Com part # 400035, supplier is Renata CR2430RH1 or Varta CR2430 PCB2.
It is recommended that the CPU card be returned to the factory if the battery needs to be replaced in order to avoid damage to the pcb. It is possible to update this version with a battery holder that would allow for infield replacement of the battery. Check with the factory if you are uncertain of the card version.

CPU card part # 710437Z
This version of the CPU card is only fitted with a battery with solder tabs and is soldered directly to the CPU pcb. This version of the battery is Clear-Com part # 400035, supplier is Renata CR2430RH1 or Varta CR2430 PCB2.
It is recommended that the CPU card be returned to the factory if the battery needs to be replaced in order to avoid damage to the pcb.

Battery Life Expectancy
Older Eclipse Omega/Median : approx 73 days.
Newer Eclipse Omega/Median with Socketed CR2477N Fitted : approx 247 days.

CPU card will retain data so long as the battery voltage remains above 1.5V.  2.5V