Converting a GBA game over to battery-less saving (SRAM to FRAM)
Channel: makho
Date: 2019-12-20

If your game is one of the 23 or so in this list (not counting Pokemon!), then it may use battery backed SRAM: https://gbatemp.net/threads/gameboy-advance-gba-games-requiring-batteries.322803/

Do note that there may be extra games that are not listed in the above list but this will still work for any OEM GBA games that use SRAM. This will not work for any bootleg or repro games or especially other GBA games that do not use SRAM. 

Early in the GBA life-cycle, some games were still being made with SRAM chips for save functionality. Unfortunately, this means that when the battery inside these carts dies (which may not be for another five to ten years depending on the cart), the save function will no longer work and all data will be lost. It's pretty easy to just swap a new battery in at this time and just call it a day since these batteries seem to last a while anyway, but there is another option. 

Quite a few games also shipped with FRAM instead of SRAM. FRAM is functionally identical to SRAM (in this usage) except that it does not require a battery to retain data. Some games shipped in both FRAM versions and SRAM versions while some games were just one or the other. In the case of Metroid Fusion, that game shipped as both but mine happens to be the SRAM version. 

All that you need to do is swap the physical SRAM chip for a FRAM chip, but if you have a compatible board donor, it's better to swap the MROM chips around that way both of your games are still functional (albeit one of them will still need a battery). All SRAM games should be compatible with AGB-E11-01 PCBs (these are guaranteed FRAM) and you can just swap the MROM chip around. See this thread for more details: https://gbatemp.net/threads/convert-sram-gba-game-to-fram-save.488447/

There is no reason you cannot back up your save beforehand and then write it back to the cart after swapping. I did not do that in this instance because I did not care about the save data on either cart. In some cases, the existing save data on the FRAM game may cause issues for the SRAM game so it is best practice to backup and restore your save data just in case. If you do not already have a cart reader capable of doing this, you can read about the most common ones in the wiki I've been compiling and maintaining: https://gameboy.github.io/wiki/cartreaders

A note on third gen Pokemon games, specifically Ruby, Sapphire, and Emerald -- these games DO use a battery but NOT for saving. The battery is for RTC ONLY so swapping these boards will only serve to break RTC AND saves. SRAM or FRAM games are only compatible with SRAM or FRAM and mixing and matching is fine. Any other games will not work with SRAM or FRAM. EEPROM games only work with EEPROM and so on.