You might have seen my other instructables showing how to put a CR2032 battery holding in a Zelda II cartridge using wires to connect to the holder so as to give the holder room in the empty top part of the cart. I also have one instructable showing a simple way to keep your saves intact when adding a new battery. Here, I'll be showing you how I placed a battery holder directly onto the gameboard spot where the old original battery once resided. As you can see I chose one of the 1st copies of the game (5 screw) to do this to since it's the copy I'm going to play when I feel the urge to get my classic Zelda on.Here's what you will need.
Soldering iron and fine solder
CR2032 low profile battery holder (I robbed this from an old fat PS2 motherboard I had laying around)
CR2032 battery (get a good brand with far off exp date so it will be sure to last many years with no worries)
Needle nosed pliers X2 (to remove the older battery from the tabs & to break off the excess tabs)
Small flat head screwdriver (for early games such as this one) or the security game bits for nes games.
metal glo polish ( may as well polish the contacts like new while you have the cart apart )
cloth ( to use with metal glo )
rubbing alcohol ( to clean off contacts after using the metal glo )
Gel pen ( optional to write the date you installed new battery which I highly recommend )
Step 1: Take the Game Cartridge Apart and Locate the CR2032 Battery.
Remove the back of your game cartridge housing revealing the gameboard. When you flip it over you will see the battery & tabs that are actually spot welded to the battery. The tabs are soldered securely onto the board.
Step 2: Removing the Old Battery.
As you can see this battery is from 1987 & despite being nearly 30 years old it still saves games, remarkable! Still it had to go because the life expectancy from Nintendo for these batteries were 5 years so it could go bad at anytime. To remove it requires a bit of brute force with the needle nosed pliers. I first pulled the battery & still connected tabs away from the board as far as possible. After that I used the pliers to grasp the tab as close to the battery weld spot as possbile & pry it until the small welds broke free from the battery. Once the upper once was free I bent the battery up & used the same method on the bottom tab connection to battery point. Next I took & desoldered & pried the battery holder from the old PS2 motherboard. I then held it up to the tabs bending them down close to the board & figured out how long the tabs needed to be to reach both the + and - sides of the holder. I simply used the needle nosed pliers to bend the excess tab back and forth until it broke at the right length. Do not bend the part that you will need because it could very easily break off at the board. You might want to use a second pair of pliers to hold the part of the tab secure that you will be keeping to prevent it from breaking.
Step 3: Solder the Battery Holder to the Board.
With the tabs at the right length to matchup with the tabs on the battery holder add a bit of solder to both tabs where they will connect to the holder and a bit of solder on the holder connection points. Be sure to not solder it in backwards. The gameboard is clearly marked + & you can look at your holder and see which part will be connecting to the + side of the battery. Hold the soldering iron tip up to the connection points & it should melt the solder together. I like to add a little more to make sure it holds after I get both sides secured. Now you can add your battery & do a test fit of the board inside the cart housing.
Step 4: See If It Fits.
Since the cartridge I'm using is a 5 screw it has posts that were made to accommodate the illusive famicom to nes converter. One was right in the middle of the way of the battery holder so I simply used cutters and needle nosed pliers to remove it. After that everything worked fine. Before putting the cart back together I wrote the date I installed the new battery inside the case housing using a gel pen.
Step 5: Test Game to See If Save Is Working.
Now test your game to make sure everything is working properly. I played through the first dungeon in Zelda to confirm mine was functioning. I can now feel confident my saves will be safe for many years to come. Happy gaming :) everyone.