How To: Replacing SNES Cartridge Batteries

As old as it makes me feel, SNES games are getting to be 20+ years old at this point. Because back in those days consoles didn’t have on board hard drives, SNES games (and others like them) save your progress using a small battery that’s soldered to the board inside the cartridge itself. Sadly, these batteries are starting to die and the ability to save progress on these old games fades once that happens.

But fear not, there is something you can do. It’s very easy, with a little practical know-how, to replace the original batteries on your carts and keep saving on these games alive for years to come. I should warn you that this process will cause you to lose all saves on the cartridge and have to start fresh, but that’s going to happen in a couple of years anyway (if it hasn’t already) and is a small price to pay for maintaining gaming history.

Super Mario Kart

Our example for today’s project.

For my example today, I’m going to be using the above copy of Super Mario Kart. I’ve actually already replaced the battery in this game, but you’ll still get the idea of what I’m talking about. Some games don’t actually have batteries to replace, which is always nice. These mostly consist of arcade-style games like fighting games and, for example, the Super Star Wars series. Just so you can see, here’s my copy of Mortal Kombat II. Obviously, it has no battery to worry about replacing:

Mortal Kombat II

Mortal Kombat II has no save system, so no battery.

Super Mario Kart, however, does use battery backup for track and lap times, as well as unlocks. The first step is to open up the plastic cartridge itself. You’ll need a security bit tool to remove the small screws that hold it together. I managed to find a set that came with 3.8mm and 4.5mm security bits off eBay for less than five bucks. A set like this will allow you to open all kinds of carts: NES, SNES, Genesis, N64, etc. For the purposes of SNES, you’ll need the 3.8mm bit:

Super Mario Kart

Use your 3.8mm bit to remove these screws.

Simply remove the screws and set them aside. They’re pretty tiny, so be careful not to lose track of them!

Super Mario Kart

I had to circle them just because they’re so easy to lose.

Upon removing the top of the plastic cart, you’ll see the back of the board itself.

Super Mario Kart

What you’ll see upon opening the cart.

If you flip it over, you’ll see the front of the board and, more importantly, the battery itself. It’s typically in the upper left corner. To replace it, you’ll obviously need a new battery. There are lots of options out there for replacements, but I recommend getting this one. It has the same style of soldering tabs as the original batteries, already attached to it. Not only does this make it look original, but the tabs make the replacement process super easy.

Now’s where soldering comes into play. Once your soldering iron has heated up enough, flip the board to the back side and hold the iron against the 2 solder points here:

Super Mario Kart

De-solder these two spots to remove the old battery.

You may have to hold it there for a couple seconds, the old solder might not melt immediately. As the solder melts down, you just have to kind of wiggle the old battery off of the board by pulling gently on it. It definitely helps to have a friend providing a second set of hands to do this. When successful, the battery will be removed and you’ll see the two holes where the tabs went through the board.

Now is a good time to take note of where the tabs were inserted on the board. The tab that’s attached to the top of the battery is the positive, and the one attached to the bottom of the battery is the negative. Pay attention when you remove the old battery which tab was inserted into which slot, because you’ll need to put your new battery in the same way. In the case of Super Mario Kart, we can see that the positive tab is on the right:

Super Mario Kart

The tab on top is positive, so positive is on the right.

Keep in mind that every game is different. For example, here’s a copy of Donkey Kong Country that I recently replaced the battery in. The tabs on this one are located at the top and bottom instead of the left and right, and the positive tab is the one on the bottom:

Donkey Kong Country

The Donkey Kong Country battery attaches to the board with positive at the bottom.

Anyway, back to Mario Kart. Simply insert your new battery onto the board by sticking the tabs through the holes (obviously making sure the positive and negative are positioned the same as the original battery). It may take a little wiggling, but the battery will eventually snap into place. Note that it may not actually be flush against the board itself, which is fine.

Flip the cart back over and you’ll see the tabs stick up through the holes. All that’s left to do is a simple solder job! Solder around the tabs, essentially securing them to the board just as it was before you removed the original battery. It doesn’t have to be nice and pretty, but there should be a good connection.

Super Mario Kart

Solder here – the same place as the old battery.

The solder will cool and harden very quickly, so it won’t be long before you can set the board back in the cart. Remember that the board goes face down in the back of the cart, it won’t fit together any other way. Using your security bit, tighten the screws back into place and you’re done!

I typically test my batteries after the job is complete. This can be done with a voltometer, but where’s the fun in that? I like to stick the game in my SNES and play up to a save point (or in the case of our Mario Kart example, do a race to save a track time). Then I turn off the SNES and remove the cart from it. I then put the cart back into the console and turn it on to check and see if my save has successfully be preserved.

If you care about keeping your library of old games fully functional in the decades to come, this is a process you’d do well to practice and get good at. The nice thing is that once you do it for a game, you shouldn’t have to do it again for another 20 years! It’s worth noting that this can be done for all sorts of cartridge-based games, but you should do research first to see if different battery sizes, etc are needed. My only experience is with the SNES, after all. I hope you found this helpful!


About heyitsthatdog

I love video games, even when they don't love me back.
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One Response to How To: Replacing SNES Cartridge Batteries

  1. Adam says:

    Some clean soldering done there by some pro.

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