Battery Capacity
The capacity of the battery differs between Eclipse32/PiCo and Eclipse Median/Omega/Delta frames.
On Eclipse32 and PiCo, a 400033Z 1/2AA 3V VARTA 6127-201-301 is fitted. This has a capacity of 970mAh.
On Eclipse Omega/Median, a 400035z CR2430 3V VARTA 6430-701-501 was originally fitted. This had a capacity of 280mAh.
In July 2008 a change to the Eclipse Omega/Median (not the Eclipse PiCo) was released (ECO4917) to replace the 400035Z CR2430 battery with a 400068Z Renata CR2477N replaceable battery in a socket. That has a capacity of 950mAh.
Battery Load
On all Eclipse designs we have the same memory devices loading the battery.  We have 8xSRAM ICs. The SRAMs take from 4 to 20uA each so 32 to 160uA in total.
Battery Life Expectancy
E32/PiCo
970mAh/160uA = 6062.5 hours or 252 days.
Eclipse Omega/Median With CR2430 Fitted
280mAh/160uA = 1750 hours or 73 days.
If the memory was replaced with a non-volatile type and the battery was only powering the real-time clock then the calculation would be: 280mAh/0.5uA = 560,000 hours or 64 years. Effectively, the life is limited by the shelf life of the battery.
Eclipse Omega/Median/Delta With Socketed CR2477N Fitted
950mAh/160uA = 5937.5 hours or 247 days.
If the memory was replaced with a non-volatile type and the battery was only powering the real-time clock then the calculation would be: 950mAh/0.5uA = 1.9 million hours or 217 years. Effectively, the life is limited by the shelf life of the battery (5-10 years).
This battery life expectancy is the amount of time that the battery should last with the unit not connected to a mains supply. Note that batteries do not recharge when a mains supply is attached.

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

Software Versions 4.2 to 5.2.4
In software versions 4.2 to 5.2.4 the following items are stored in NVRAM and would be lost if the unit were powered down with a depleted battery:

• Key latch state
  
  

• Locally assigned keys

• Online mode assigned keys, forced listens and blocked listens

• Xpts and Xpt level changes made at Xpt map

• Online changes to line input and output levels

• Production maestro (and HCI client) routes, level changes, partyline membership changes
  
  

The IP address information and Current configuration in use parameters were moved into the non-volatile one-wire memory device which does not rely on the battery for its non-volatility.
Software Version 7.0 and beyond
In software version 7.0 and beyond the following items are stored in NVRAM and would be lost if the unit were powered down with a depleted battery:

• Key latch state

• Locally assigned keys

• Online mode assigned keys, forced listens and blocked listens

• Xpts and Xpt level changes made at Xpt map

• Online changes to line input and output levels

• Production maestro (and HCI client) routes, level changes, partyline membership changes
  
  

This is the same list of items as in v4.2 to v5.2.4 but an additional parameter, frame type, is also stored in the non-volatile one-wire memory alongside IP address information and Current configuration in use.