Best Battery for GBA sp 2019 Edition

[Adrian-E-C]

What is currently the best battery you can put into a GBA sp? I know with some slight alteration, you can fit a DSi battery into an SP, but can the same be done with the much larger capacity DSi XL battery? Are there any other batteries that are even better?

I would love to hear opinions on batteries and brands that you are all using for your SP, and where is the best place to purchase a quality one. I am in Canada FYI.

 

[Ryccardo]

I know with some slight alteration, you can fit a DSi battery into an SP

DS you mean, where it's only a matter of breaking off the tabs? (and indeed an original DS battery from 2005 or so, lightly but appropriately-often used is what I use)

With more effort (ie replacing the connector and/or case modding) pretty much any single-cell (protected) lithium battery can be used, for an enthusiast with good CAD skills and a 3d printer there's their opportunity to make a worthy successor to the 40 hours of the original GB