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Comment by tenpoundhammer | Hacker News Reader

Based on the video posted below by coob ( https://www.youtube.com/watch?v=5vOuj_feM2s) it looks like it utilizes a well known re-active element ( Zinc-Oxide) to generate electricity.

http://sci-toys.com/scitoys/scitoys/echem/batteries/batterie...

So the real question is, how long does it take for the Zinc Oxide to be depleted, how much does it cost to replace, and how hard is it to replace?

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From the landing page: "Using SALt lamp 8 hours a day every day will give you an anode lifespan of 6 months."

Okay, with a pair of big electrode plates, retail cost will be, what, $200?

You can get a 12" square sheet of zinc for under US$10 and make a couple dozen anodes from it.

Copper cathodes will be a bit more expensive, but the total electrode cost should still be only a few dollars for several months worth of light.

The electrodes are going to have to be pretty thick, chunky grids to last six months, not thin sheets, and retail price is typically a 100% markup over BOM cost.

Or the cathode is carbon. Then (IIRC) it wouldn't wear out or need replacing.

http://en.wikipedia.org/wiki/Galvanic_cell

The has energy come from somewhere. In an electrochemical battery, it comes from chemical reactions with the electrodes, which consume the electrode material.

As VLM explains a bit better, I was talking about only one of the two electrodes. The other one, the anode, would of course be made from zinc (or some other metal) and end up breaking down to provide that energy. I was just explaining why the battery might not need two electrodes breaking down.

Its basically one of these:

http://en.wikipedia.org/wiki/Zinc%E2%80%93carbon_battery

The carbon rod never corrodes. If you want to be picky its more of a zinc-manganese battery with a carbon rod as a non-corrosive wire but whatever.

>So the real question is, how long does it take for the Zinc Oxide to be depleted, how much does it cost to replace, and how hard is it to replace?

…and don't forget "how poisonous is the stuff you're dumping out?" (straight into the environment, your water/food source)

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