Recently debuting at #1 on Digg.com was a story on a laptop battery that could last 30 years. This story got more Diggs than a video of a monkey pwning you in Halo 3 would have, but no one seemed to ask, "Really...for real?"

The technology is actually quite fascinating. It's a "betavoltaic" power source. These actually exist. And they work by getting together a lump of radioactive material (like tritium) that emits beta particles and then converting the beta particles to electricity. It's just like photovoltaics...except instead of photons, it's beta particles.

This device isn't a battery, it's actually a power source, and it will indeed continue producing power for 30 years (the half-life of tritium is 12 years, so it will be producing roughly 25% of its power 30 years from now.) But the article doesn't point out that there are significant problems with the technology, specifically when using it as a laptop battery.

So what are the problems?

1. To power a laptop, you'd need about 50 lbs of tritium. Researchers plan on surmounting this by trickle charging a battery with the betavoltaic. This way, when the laptop is not in use, the battery would be recharged by the betavoltaic power source. But while using the laptop, you'd experience nothing more than an increase in life...not a 30 year battery.
2. While the article states that these laptops would run cooler than Li-ion laptops, that's quite wrong. Betavoltaics lose about 75% of their energy as heat, and as designers will be required to include Li-ion batteries anyway, I imagine, if anything they'd be hotter.
3. At the end of its, life the power source would be completely innert, but during use, it wouldn't be. Moderate shielding can easily block beta waves, but if the battery were damaged, and then you placed it on your "lap" I would hate to think of the consequnces.

I'm not saying that this technology isn't useful. In fact, it's very useful, particularly for space missions requiring low but constant power. Or for any device that needs a low voltage for a long period of time and is difficult to access.

The possibility of trickle charging a Li-ion for increased life is intriguing, and certain low-power cell phones may someday be able to run 100% on betavoltaics. But a 30-year laptop battery, I'm afraid, doesn't look likely.

Via ZDNet

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