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Comment by fsh | Hacker News Reader

There are betavoltaic generators [1] that directly produce electricity from decay electrons using p-n junctions (similar to photovoltaic cells). However, in the vast majority of applications, they get outperformed by modern lithium batteries (i.e. coin cells).

[1] https://en.m.wikipedia.org/wiki/Betavoltaic_device

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How can you compare a generator to a battery? How do you charge the battery without a generator?

A bettery, from the viewpoint of a circuit, is just another source. So we could call them chemical electricity generators, if we're brave enough to indulge the confusion

I still don't quite understand it. Where does the battery get the energy? I understand that there's no difference in a circuit, but why is this comparison relevant? Many power sources are way less efficient that using a battery, but we need to charge the battery.

For low-enough-power applications and sufficiently long-lasting batteries, charging is just another step in production.

Betavotaic generators usually produce extremely low power. A similarly sized battery can last for decades at the same power output.

Alkaline batteries are never charged, per se. The energy comes from the one-way chemical breakdown of cathode and the anode.

Betavoltaics aren't really either - they provide a constant, slowly-over-years declining flow of power. They can't be recharged, they _could_ be refueled (don't know if it's economic though), and are mostly used when you need a small flow of power and a long period of time between maintenance (think pacemakers, weather buoys, some satellites or probes).

I believe GP means a disposable battery that you replace with a new one when it's empty. Not a rechargeable battery.

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