I used to own an iEdge cart which people say a Cyclods lite. Now all I have is a DSTwo and an R4i Gold Pro (ntrboot). I wish I bought an acekard during the ntrboot craze.
I found this for fats recently it's pretty good compared to the other third party batteries you might get better life with that lol https://www.retromodding.com/products/makho-game-boy-advance-sp-battery