Most Game Boy games (and by that I mean the pre-Advance time) are saved into the cardridge and powered by a battery so that this memory will not vanish.
In a future, far far away, the battery empties, which will lead to a loss of the save state as there is no power source to hold the save state in the memory.
A solution is to replace this little battery and have a saveable game again. So I'm now playing Dragon Warrior Monsters and achieved pretty much everything in the game. I know I will play that game again (as I replay it often since release).
My fear is that I will lay back the cardridge until digging it out again. By that time the battery may already be empty (never replaced it since I bought the game).
What are my options if I want to replace the battery precautionary and keep my save game?
(This may include tinkering tips, extra hardware or a simple "won't erase your save game anyway".)
I ask this question specifically for the "pre-Advance" GameBoy cardridges:
Best Answer
Open the cartridge and plug it in a GBA. Turn it on and exchange the battery while the system is on. Just make sure to not touch any contacts that could damage the cart, focus on the battery and make sure it doesn't lose power while you're working on it.
This works because when the batteries start to wear out, they can still work through the GB's own battery, but once that one also runs out, you'll be out of power for both the cart and the system.