Hi @Eloi,
This is something we have considered and begun to explore, but there are some challenges to overcome. Keeping a good balance of price, discharge capability, clean design (that doesn’t look suspicious) and still adheres regulations by the book and in practice is a bit tricky. This also all still needs to fit comfortably inside the existing battery enclosure.
You might want to check out this alternative that @etienne has been working on.
-Adam