Asklemmy

The first generation Pokemon games all used significantly less power to maintain their RAM battery saves than Pokemon Gold, Silver, and Crystal by virtue of not having a real time clock constantly ticking the power away. RBY saves only needed to maintain the power for the save itself and did no additional work on top of that.

Original GSC cartridges would last about 10-15 years, whereas RBY could last 20-30 years. We're currently in the span of time where many RBY cartridge batteries will be failing but it's still possible to find ones with functional original saves on batteries just barely holding on.

Many people like to try using physically larger batteries when doing replacements, but most of them don't realize the batte ries aren't losing charge at the end of those many years because they're drained and out of power. RBY saves use so little power from the battery in the cartridge that they won't fully drain it after 30 ish years. Instead the battery saves fail because the batteries themselves fail after 20-30 years. Picking the larger button cell batteries won't help since they'll still have the same total lifespan and will still lose charge at almost the same rate as the spare batteries that weren't installed in your cart ridge of choice.