Dreamcast Time/Date Repair Guide and Work Log


Did you ever turn on your Dreamcast and get this screen?


Odds are the CMOS battery in your Dreamcast is dead.

Tools you will need:
Soldering Iron
Phillips Screwdriver
Wire cutters and wire strippers
Safety Glasses/ eye protection

Optional: Multimeter

CR2025 battery cell holder
CR2025 coin cell battery
Doubled Side foam mounting tape

Optional: Electric tape or shrink wrap

WARRING: Although this is a simple mod, you are going to be working with a hot soldering iron around a battery Wear Safety glasses/ Goggles or other form of eye protection, and do not keep the hot soldering iron too long on the battery.

You can substitute the CR 2025 with a similar 3 volt coin cell or 2 more standard batteries like AA that will at up to 3 volts (1.5 volts each). Use only rechargeable batteries, DO NOT USE Alkaline batteries please.

Reason I want to use a battery holder instead of soldering on battery cell is because, if I have to repeat this process in the future, I want to save as much work as possible. This way I do not have to solder directly to the battery. Also exposing a battery, charged or dead to excessive heat is not advisable.

  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.



  1. 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.

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

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

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



This pic was made post op


Board removed

  1. unsolder the 3 pins holding the battery to the board.

Best way to go about this is flip the board over and de-solder the 3 pins holding the battery in place
I removed some solder with a de-soldering wick, then push down on each pin with my iron. At no time should the soldering iron touch the actual cell.

Dispose of the old battery according to your local laws concerning battery disposal.


  1. solder in 2 wires on the PCB for the new battery holder, keep in mind which spots on the board the plus and minus terminals went. The Plus side is labeled on the board.
    10a. if required solder the wires to the appropriate terminals to the battery holder
    Also take a note which terminal is positive and negative.

You should not have installed the battery into the battery holder until all the soldering in this project is DONE.


New CR2025 battery and CR2025 battery holder.






Now the hard part is done

  1. replace back in the circuit board back into the Dreamcast

  2. Reattach the ribbon cable and fan connector

  3. attach the battery holder to the inside using a self adhesive, like double-sided foam mounting tape, self adhesive velcro would work here too. Now you can place in the battery into it’s holder.

  4. Replace the top cover of the Dreamcast and replace the 4 case screws

  5. Put back the modem

  6. Hook up your Dreamcast to your TV or Monitor and reset the time & date

  7. ???

  8. Profit

And yes this is almost identical to the Instrucible also written by me.
I am Head Wound on Instructibles
Repairing a Dreamcast Time/ Date


If any one got any questions on this repair/ Mod let me know, and I try to answer them.
Also please let me know if I left any details out, I will go back and edit in any missing info.


Good guide, but when working with both a soldering iron and a battery, dead or not, it would be wise to warn someone to wdar protective gear, goggles at least. Lord knows we don’t someone to get battery fluid in their eyes if they have a mishap.



True, Safety first. And quoting Norm Abram of This Old House/ New Yankee’s Workshop, “there no more important safety rule than these, safety glasses” (while pointing to his own safety glasses). Then again you be surprised how many guides leave out safety rules and safety measures. Considering all guides assume you posses a certain amount of preexisting knowledge.

**Safety Warring added ** to guide


Correct me if I’m wrong, but isn’t this fairly dangerous?
The dreamcast uses a rechargeable 3v battery (3v MnO2-Li from what I’m reading). Won’t the dreamcast (potentially) try and charge this battery and make it explode?


“but isn’t this fairly dangerous”?
Nope, not at all. For this mod the soldering iron more dangerous than the battery alone. Although I do understand your concern.
I used a CR2025 which is the same battery used on PC motherboards for there CMOS to keep time, date and BIOS settings saved. My CR2025 is also a Li type chargeable battery.

All CR2025 (that I know of) are found as Nickle-cadmium, Nickle-hydroxide or some form of lithium or Li-poly, all suitable for recharging. The battery chemistry you want to avoid for this mod at all cost is Alkaline batteries.

Yes overcharged batteries will explode. Fortunately with rechargeable batteries in this application is not a huge concern. This isn’t a issue here since the main board of the Dreamcast have a voltage regulator to know when to shut off the charge to the CMOS battery, just like PC motherboards.