What country? AFAIK in the US you can’t make the batteries replaceable. If they are wirelessly linked they can have auxiliary batteries for that, but (I believe) that’s different than the main battery…
EDIT: I seem to be thinking of California, maybe not all of US.
AFAIK in the USA you can’t have the main batteries be replaceable (I think an aux battery for wireless functions is allowed…).
EDIT: I seem to be thinking of California, maybe not all of US.