In gaming, there is nothing more devastating than losing a save file you worked hard on. In retro cartridge based gaming, save files are generally stored on the cartridge and a small amount of power is supplied to the cartridge by an on board battery to retain the data. Today, some of these batteries are 30 years old and a lot of them are at the end of their life cycle. Once that battery dies, your save files die with it. I have had this happen to me more times than I care to admit, but the most heartbreaking instance was when I was playing Final Fantasy II on SNES.
I had put in many, many hours, loving every minute of it and I was about to face the final boss. It was very late on a Friday night and while I wanted to continue on and beat the game, I was just too tired. I remember thinking to myself, "I will just save right here before the final boss and crush him tomorrow morning. That will be a fun way to start my Saturday." I rolled out of bed the next morning and flipped on my SNES only to be greeted with the opening story crawl, which only appears when no save files are present on the cartridge. I panicked, and reset the system again and again, but I knew they were gone. The battery was dead, and so was my quest...
If this has happened to you I am sure you want to know not only how to fix your cartridge, but how to prevent this from happening again. I now make sure I have replaced the save battery in any game I plan on playing through before I start and I recommend you do so as well. Here's how to do it.
STEP 1: OPEN THE CARTRIDGE
The first thing you will need to do is open up the cartridge to gain access to the battery on the PCB inside the shell. Different cartridges have different fasteners but for the example of a SNES game, you will need a 3.8mm security bit screw driver. These are easily found on Amazon and if retro gaming is a hobby you enjoy, you will certainly need a set of these eventually. Open up the cartridge by removing the security screws and remove the PCB from the cartridge shell. Be sure to put the screws somewhere safe.
STEP 2: ADD NEW SOLDER TO THE PINS
Next, we will heat up our soldering iron and add some new solder to the battery pins. This may seem counter intuitive, being that we are trying to remove the battery, but adding new solder will help heat flow to the old solder much more efficiently and ultimately make the job of removing the battery easier. At this point, take a look at the orientation of the battery and note which pin is positive and which is negative.
STEP 3: REMOVE THE BATTERY
This is the trickiest step. I like to remove the battery one leg at a time. To do this, secure the PCB safely somehow so you don't have to hold it and can use both hands. A set of helping hands and a clothes pin, like I have shown, can do the trick but if this isn't an option just ask someone for help. Next, apply heat to one pin of the battery from the underside of the PCB. Once the solder becomes molten gently pull on the battery from the other side so that the pin comes out of the hole and remove the iron from the board. Pull too hard and you may pull a trace off the board, so be careful. Wait 10 to 20 seconds or so to let the heat dissipate and repeat this process on the other pin. It is important not to put too much heat into the board at once, as this could cause damage to the game in a number of ways.
STEP 4: CLEAR THE HOLES OF SOLDER
Now that you have the battery out the pin holes will almost certainly be clogged with old solder. These obviously need to be cleared so we can install the new battery. I use a desoldering gun to clear old solder away but any desoldering gear will work for this task. You can use desoldering wick or a solder sucker, which are much cheaper tools that will get the job done. However you choose, clear the old solder so the hole and pads are clean as shown.
STEP 5: CHOOSE AND TEST THE NEW BATTERY
New batteries for video game cartridges are thankfully very easy to get a hold of today. NES, SNES and N64 for example all use a CR2032 batteries, which is a very common battery size to this day. You could simply walk down to the corner store and buy one, but instead search online and buy some that already have solder tabs installed. This makes installing the new batteries much easier and cleaner. I buy CR2032 batteries with tabs on ebay in bulk, and they are fortunately very cheap. Once you have a new battery in hand, test the voltage with a multimeter to make sure it is good. I have received a few dead ones before. CR2032s are supposed to be 3 volts, so the one I have selected is perfectly fine, reading 3.34 volts.
STEP 6: SOLDER IN THE NEW BATTERY
Soldering in the new battery is as easy as orientating it correctly, inserting the pins into the holes and soldering them down. I like to fold the legs over a little to hold the battery in place as I solder it. Soldering it in backwards won't hurt anything, but it won't work. If this happens just repeat the process from the beginning and reorient the battery.
STEP 8: REASSEMBLE THE CARTRIDGE
All that is left to do now is reassemble the cartridge and test it. If you forgot which way the PCB goes into the cartridge shell don't worry, they only go in one way. After completing this process your game that wouldn't save before should almost surely be fixed. However, I did once have a copy of The Legend of Zelda: Ocarina of Time that was not fixed by installing a new battery and I never was able to get that particular cartridge to save again, but that was the one and only time. Your game should now be good to go for another 30 years of gaming, give or take, so pop it in and enjoy!