I'm amazed that my original Pokémon Red lasted as long as it did - but the in game battery will eventually die. If you really want to save it I highly recommend using a cart dumper, something like the gbxcart, to save your file elsewhere.
I had lost my original Red had died but my first big team is saved onto Pokémon Stadium which gives me a good chuckle anyone I put that in.
Ah hello, Tim.