Malfunctioning of C-bus 2 channel digital clock

Hi,

I have problem with my E5031V2TC7 2 channel digital clock. The clock loss it programmed schedule stored in the memory except the date and time. I have experience total program memory loss due to power fail on this module for more that 24 hours (hardware limitation). That include date/time and programmed schedule. Please help me to solve the following questions:-

1) In what condition will the clock module loss it programmed schedule (programmed on & off time for each channel) but not the date and time (Timming that the programmed schedule base on).

2) Is there a economical way to extend the memory for 3 days after power failure (additional backup power)?

Regards
Peter