Is your Dreamcast time and date always need resetting.
Every time you shut the power, your Dreamcast lose its time and date settings?
Perhaps your Cmos battery died in your Dreamcast.

Tools you will need:
Soldering Iron
Phillips Screwdriver
Wire cutters and wire strippers

Optional: Multimeter

Materials:
Wire
Solder
CR2025 battery cell holder (or other battery holder depending on your batteries)
CR2025 coin cell battery (or other type of 3v battery)
Doubled Side foam mounting tape

Optional: Electric tape and/or Electric shrink wrap

Step 1: Disasembling Your Dreamcast

1. Flip your Dreamcast upside down.

2. Remove the modem from your Dreamcast

3. Remove the 4 Screws holding your Dreamcast shut.

4. Flip back over and remove the top of the system's case.

Step 2: Removing the Circuit Board

5. Once you have the top of your system case off, locate the circuit board that has the CMOS battery.
5a. (optional) If you have a multimeter or other volt tester you can test the battery to see if it is dead or not.

6. Locate 4 brass screws on this circuit board, it should be near the controller ports, remove them.

7. Then carefully remove the ribbon cable by pulling upwards .

8. Carefully remove the 3 pin connector going to the Fan to the Right

Step 3: Replacing the Battery

9. unsolder the 3 pins holding the battery to the board.
10. solder in 2 wires for the new battery, keep in mind which spots on the board the plus and minus terminals went.
10a. if required solder the wires to the appropriate terminals to the battery holder

Now the hard part is done

11. replace back in the circuit board back into the Dreamcast
12. Reattach the ribbon cable and fan connector
13. attach the battery holder to the inside using a self adhesive, like double-sided foam mounting tape, self adhesive velcro would work here too.

14. Replace the top cover of the Dreamcast and replace the 4 case screws
15. Put back the modem
16. Hook up your Dreamcast to your TV or Monitor and reset the time

17. Enjoy