Because the battery would be too heavy. It's a 6x8mm cylinder, fingernail-sized. They're little pellets that get inserted into larger machines for medical imag

Because the battery would be too heavy. It's a 6x8mm cylinder, fingernail-sized. They're little pellets that get inserted into larger machines for medical imaging. See also (or don't, it's a bit gruesome): the Goiânia accident. https://en.wikipedia.org/wiki/Goi%C3%A2nia_accident https://en.wikipedia.org/wiki/Goi%C3%A2nia_accident