Continuing my ongoing quest to make replacing batteries on your retro consoles a tab bit more informative, here is my next attempt: How to Replace the Game Saving Battery to a Sega Genesis Cartridge. I found my second attempt to be much quicker than my first. The battery swap only took me about 5 minutes from start to finish and with a little patience and some minor soldering skills; you should have no problem swapping out the battery.
Reminder: You will lose your saves when you replace the save battery. There is no real easy way to avoid this problem. Yes there are complicated methods like adding a slave battery but I just find this method to be cumbersome and not worth the extra risk.
My belief is that the only proper way of replacing a battery is to unsolder the old battery and resolder a new one. This is how the game was assembled from factory and I feel this is how the battery should be replaced. You will need to have some basic soldering skills to complete this task. This walk-through can be applied to any gaming cart that requires a small button 3V battery (with 2 pin leads), but because I can’t be sure of your soldering abilities and there is a potential risk since you are applying heat to a battery, I cannot be held responsible if you damage your game or hurt yourself.
I repeat: I will not be held reliable for any bodily damage or damage that is done to your property.
- Soldering Iron- I paid about $100 for my Weller soldering iron because the better Weller soldering irons are grounded to the tip so there is less of a risk of shorting out your PCB.
- Protective goggles
- Cr-2032 button battery WITH 2 pin leads attached. The battery that I’m using for this project is a CR2032-T.
- Electrical Solder
- Solder Sucker
- Socket Screwdriver
- 4.5mm Security bit (which can be found on eBay for about $3)
- Electrical Tape (optional)
- Plenty of room to work.
Pictured below is your standard North American Sega Genesis cart.
Place the 4.5mm security bit into your socket screwdriver and remove the two security screws. Place these two security screws in a secure and safe place so they won’t be lost.
Gently separate the two halves of the Genesis cart, revealing the game’s PCB (printed circuit board). With the cart open, you will see the bare PCB. You can see the two points that the battery is attached to the PCB (as shown in the picture below).
If you flip the PCB over (In top view) you can see the battery attached to the board next to the proms.
To unsolder: Apply heat to the battery tabs and wait for the solder to liquefy. Once the solder is in a liquid state, remove the solder with the solder sucker. Repeat in till the majority of the solder is gone and the pin is fairly loose.
Repeat with the other pin.
Your cart is now ready for installation. Take to fresh CR2032-T battery out and make sure the pins are facing the proper direction. The positive (+) pin should be closest to the proms on the under-side while the negative (–) pins is closest to the edge.
Remember: The pin that is coming off the top of the button battery is the positive (+) while the pins coming off the bottom is the negative (–)
To make it easier to install, bend to the tabs inward so the battery is clinging onto the PCB. Apply solder to both pins. When you are finished, your cart should look like the picture below.
Place the PCB into your Genesis to test it. Get to a point in the game where you can actually save a file onto the cart. Power off the machine. Wait a few minutes then power back on. Your save file should still be on the cart.
Now just assemble the cartby placing the PCB back into the casing and tighten down the 4.5mm security screws. Shake the cart and make sure nothing is loose. Re-test the game and verify that the save is still present.
Congratulations! You have just replaced the game saving battery to a Sega Genesis cartridge. Enjoy your game for another 10-20 years.