Why does it say my internal battery has run out?

Your Gameboy Adv/SP/DS all use battery packs. As you recharge them, the battery packs lose a little power. Once you use up the battery's power, it stops working, and you have to get it replaced.

Restarting the game mught help you....or buy a new cartridge and see what happen's...try to borrow your friend's Ruby if they have one if the same thing happen's it's mostlikely that your GBA/SP is broken...sorry.

On my brothers emerald, it says "the internal battery has run dry", it has said this since the start, but the game works perfectly ok apart from anything clock based can't happen, like growing berries.

This happened on my Ruby too. Like Tails93 said, it stops the clock from working and berries from growing. I guess it is because the clock has to have something powering it even when it isn't in the gameboy, a bit like a watch. I don't think anything CAN be done to fix it, but if you ever get a chance to go to a Nintendo event, you should take it along and ask them there, they should know. Hope this helps.

I think that u should just replace your gba/sp/ds battery pack

The real reason why this happens is because the game runs on a clock-like thing , and it has stopped working. There is no problem except that tides don't come in shoal cave and berries don't grow.

There is a little watch like battery inside the system if you take the 4 screws of the back you can replace it

This is an old thread, but as I know a thing or two about the cartridges, I'd like to confirm that it's just like the game says, the battery on the game cartridge has run out. Certain GBA games have a clock that runs on a small watch battery, once it runs out, it needs to be replaced for certain time-based features to work. You need a special screw driver to open the cartridge and possible will need to resaulder the battery holder (not sure, since I havent had to change one of these personally).