All retro consoles featured some kind of battery-powered memory to store user progress, while ROM was reserved for game data. Back then, game cartridges used mask-ROM which cannot be altered once data is written onto the circuits. They also used SRAM to save your progress, and this is volatile memory that loses data if power is turned off.
Why do Gameboy cartridges have batteries? Batteries are needed to power the SRAM chip even after you remove the cartridge from your console. Otherwise, the volatile memory will stop retaining data and you’ll lose all progress made within the game (along with characters, unlocked areas, etc.).
These days, SRAM chips aren’t required as games are stored on read-only data going into a hard drive/ cloud storage. Plus the ones that do come on cartridges save data to the console’s internal memory. Either that or the cartridge includes a flash chip (rewritable non-volatile memory) to store user progress.
Why Do Gameboy Cartridges Have Batteries?
To understand why Game Boy consoles use batteries in their cartridges, we must first take a look at how a Game Boy cartridge works. As you already know, cartridges contain the code and various assets needed to run games. If we talk about a modern handheld game console, Nintendo’s Switch is the prime example.
However, Switch cartridges have no rewritable memory and only contain game data. User progress is saved to the internal memory (or cloud storage if you have a Switch Online subscription). Things were very different with Nintendo’s first handheld console- the Game Boy.
You see, a Game Boy cartridge contains 3 different chips. First, it has a ROM chip for game data. Then, there’s a memory bank controller (MBC) that acts as an I/O manager, providing your Game Boy with the data it requests from this ROM chip.
Finally, you have a Static RAM (SRAM) chip that is much smaller in capacity than the ROM chip. This is responsible for storing user progress. When you unlock a new area on the map, complete a level, or purchase certain items, all of that information is updated here.
As SRAM is volatile memory, it loses all data if the power is cut off (unlike ROM which is non-volatile). If your cartridge is plugged into the Game Boy while you’re playing games, it receives power from the console. As soon as you remove that cartridge, an internal coin cell kicks in and powers the SRAM.
If this coin cell (model CR1616) dies, you will lose all your saved data. This is why so many Game Boy restoration projects replace the old coin cell with a fresh one. If you’re buying an old game cartridge online, you have no way of knowing whether it’s still carrying the original cell or a replacement cell.
How Long Do Gameboy Cartridge Batteries Last?
Based on the research done by a person on the AtariAge forum, cartridge battery life for GB consoles can vary from 15 to 40 years. This depends on the battery model, temperature, and other factors (like whether your game has a real-time clock). Game Boy and Game Boy Color cartridges use coin cells which come in two models- CR1616 (50 to 55mAh) and CR2025 (150 to 170mAh).
If your game cartridge was made before 2000, it probably uses the smaller CR1616 battery. Games made after 2000 use CR2025, which has thrice the capacity. The SRAM chip used in Game Boy cartridges could be low-power, or very low-power.
Typical data retention current draw is 0.3 to 0.4 µA (microamperes) at 25°C. And the minimum voltage at which these SRAM chips can retain data is 2V (CR1616 and CR2025 operate at 3V when not depleted). If you want details, here is the datasheet on a Sharp LH52256CN-10LL 256K SRAM chip used in Pokémon Blue.
Cartridges with CR1616 can retain saved data for 15 ± 5 years. If your Game Boy cartridge uses CR2025, it can retain data for around 40 years. Game Boy cartridge batteries are not hot-swappable, so you need to back up your saved data before you replace the battery.
What Batteries Do Gameboy Color Cartridges Use?
Game Boy and Game Boy Color use either CR1616 or CR2025. C means it’s either manganese dioxide or lithium (modern ones are lithium). R denotes the shape, which is cylindrical.
The four digits following CR tell you about its dimensions. The first two digits are diameter in millimeters, and the last two are height in 1/10th of a millimeter. A CR1616 is a lithium coin cell that measures 16mm wide and 1.6m tall.
Larger batteries have more capacity, but they also need to fit in your Game Boy cartridge. To open your Game Boy cartridge, you need a 3.8mm security bit screwdriver. You must purchase replacement units with pre-soldered tabs, as soldering tabs to the battery by yourself will cause the lithium cell to explode.
Do All GBA Cartridges Have Batteries?
No, most GBA cartridges use programmable ROM (EEPROM) or Flash memory. Some of the early games use batteries, to power SRAM chips for saved data. Examples of GBA titles that use batteries are- Baseball Advance, Mega Man Zero, Breath of Fire, Metroid Zero Mission, etc.
You can view a fairly comprehensive list of GBA games that use batteries here. These battery-powered game cartridges form a tiny fraction of the 1000+ games in the GBA’s library.
Do Fake GBA Games Have Batteries?
Unless it’s a well-done fake intended to fool the customer rather than make a profit, no. Fake GBA games are easy to distinguish from real ones after you take the cartridge apart. They also tend to combine multiple chips into one, so you will have missing components on the PCB in addition to the missing battery.
Original Nintendo cartridges have copyright marks on the circuit board, which you won’t find on fake cartridges. Fake cartridges also have off-color labels and typos. If the dimensions on a fake cartridge aren’t right, it will require a fair bit of effort to slide into your Game Boy’s cartridge slot.
What Happens When A Gameboy Battery Dies?
Nothing that you will be able to notice from the outside. But when you put the game into your console you will discover something is wrong. Even though the game boots up and plays normally, all of your saved files will be gone.
To fix this, you need a flash dumper for your Game Boy cartridges. These are specialized devices that create a copy of all data stored in your game cartridge. They are also used by retro gamers to create backup copies of their games and reproduction cartridges.
I hope this article helped you understand why Game Boy cartridges have batteries. They are necessary to power SRAM chips that store user progress, as well as special functions such as the real-time clock used in certain RPGs. Replacing the battery on a Game Boy console is fairly easy, just make sure you’re purchasing the right model.
You need a pre-tabbed CR1616 or CR2025. Don’t solder tabs to a naked battery by yourself, it’s too risky and might cause a fire hazard. You also need a 3.8mm security bit screwdriver to open your Game Boy cartridge.