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Comment by ajnin | Hacker News Reader

This is cool stuff but I'm not sure what application this is targeted at. Primary lithium cells have a 15 to 20 years operating life, and contrary to those batteries you can draw more power on demand when you need it and stay asleep at low current the rest of the time. Energy density seems higher but not that much.

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15 to 20 years operating life on a single charge? Or 15 to 20 years operating life if you recharge them occasionally?

"primary lithium cell" means a non-rechargeable lithium battery.

Primary means not rechargeable. Secondary is rechargeable.

This is not a battery per se, it's really a generator. Over 20 years this thing is worth something like 20 watt-hours, but is far smaller than the equivalent primary cell (because it doesn't store energy, at least not chemically) and doesn't have issues with current leakage. It's meant for powering super long-lived low-power devices, one example that comes to mind that could benefit would be the container monitors used by the IAEA for monitoring nuclear material.

The energy density of this betavoltaic battery is only about half that of an LiMnO2 primary-cell battery, about 370 mWh/cc versus 650 mWh/cc. Examples of LiMnO2 batteries are the extremely common CR2032 or CR2450 coin cells.

Self-discharge isn't much of an issue with LiMn02 batteries, either, at only 1% per year.

And, of course, LiMnO2 cells have the benefits other commentators have mentioned, such as the ability to supply more than just 75 uA short-circuit.

Hmm, I was looking at the wrong figure on the page, the higher power model is much bigger than I was estimating from the pictures. Still, I imagine these at least have more stable performance at extreme temperatures. Would be nice if they had a real datasheet but I don't see one.

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