Watched some YouTube videos with battery replacements on older Sandisk MP3 players, Clip zip etc. and saw 290mah a few times.
Did a search for replacement batterys and 290 showed up again and also 550mah as a extra power replacement battery.
Considering that those cells are 3.7 volt cells and since most powerbanks are 5 volt (standard usb) there should be an advantage when calculating Your mah needs, can’t tell how much of an advantage though.
