Now that I have an extra backup of my Mega-CD save files on the Sega CD Ultra Backup RAM cart, I can replace the battery of my old CD BackUp RAM Cart without worrying about data loss.
It is possible to do an open-heart surgery to prevent the memory from being erased and replace the battery while the Mega-CD is turned on. I went for that procedure to avoid having to copy all files from one cart to another again.
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_07-1024x670.jpg)
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_08-1024x577.jpg)
Two screws are hidden behind the label on the back. Try to be careful when lifting the edges of the label (I wasn’t):
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_09-1024x617.jpg)
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_10-1024x698.jpg)
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_11-1024x922.jpg)
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_12-1024x935.jpg)
The battery is a CR2450 3V Lithium cell. As space is very limited, a cell holder probably won’t fit. Use a cell with solder tabs instead.
To prevent the cart from moving in the slot (e.g. when using a desoldering pump), secure it with a piece of polystyrene or rubber.
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_13-1024x518.jpg)
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_14-1024x508.jpg)
Old battery removed and system status checked: still running, save files are still there – it’s time to clean up the PCB holes and solder the new battery.
When the new battery is in place, turn off the Mega-CD and inspect the three solder points. Add more solder if required.
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_17-1024x587.jpg)
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_16-1024x568.jpg)
Final check and a reminder to be careful with the back label:
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_19-1024x664.jpg)
![Sega CD BackUp RAM Cart](https://retrostuff.org/wp-content/uploads/2016/05/backup_ram_18-1024x549.jpg)