Assuming you could get these to 10% efficiency (which is theoretically possible) and a phone needs 0.2W of energy to function then you would need a source capable of supplying 2W of energy (of which 1.8W would be dissipated as heat). The phone would be fairly hot all the time but 2W could be dissipated without it overheating in most environments. Strontium 90 generates 0.95 W/g so in theory a few grams of strontium 90 would be enough to power your phone for many decades (the half life is 28 years). But if someone were to accidentally put such a phone into an insulating material it might overheat and become a dangerous radioactive mess!
close04|7 months ago
For an arbitrary definition of "function". I don't think a modern phone would achieve a meaningful function at that level. The cellular modem alone blows past that budget many times over. Even an old rotary phone went over 1W.
Apple's efficient 5G "C1" modem used in the iPhone 16e is still at ~0.7W. The Qualcomm models used in the iPhone 16 are 0.8-0.9W.
exe34|7 months ago