Every smartphone built in the last twenty years assumes the same thing: the battery will be charged once a day. Before I get to the math, sit with this for a moment: what would actually change if a phone never needed to be plugged in?That is what I am building. The power source is betavoltaic — electricity generated continuously from the decay of a radioactive isotope, with no moving parts, no combustion, no charging infrastructure.The device I am describing is not a current smartphone with a different power source. It is a device designed from the ground up around a power budget that current betavoltaic technology can sustain. Day One capability is meaningfully more limited than a 2026 flagship phone. That gap closes as the power architecture advances.The source physics:Tritium (H-3) decays by beta emission to helium-3.The emitted electron carries a maximum energy of 18.6 keV, with a mean energy of approximately 5.7 keV. The neutrino carries the rest and is unrecoverable. The beta spe...