Comment by jellicle | Hacker News Reader

Comment by jellicle | Hacker News Reader

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So this is a battery-powered lamp, where the saltwater is merely the electrical conduit and the battery consists of the cathode and anode, perhaps carbon and zinc. We already make batteries of this type, without the gimmickry:

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

This same lamp could simply have a wire between the carbon and zinc, with an on-off switch - no need for saltwater except to fool people into thinking the salt is providing the energy.

It's very hard - impossible - to imagine how this device is superior in performance or cost-effectiveness over any sort of commercial light with a battery. An LED or three connected to a lantern battery, auto battery or other "large" battery will last forever, with self-discharge being the biggest problem.

LEDs with solar cells are nearly free, and last forever. Here's one for $1.98 retail, Canadian:

http://www.lowes.ca/solar-landscape-lights/paradise-stainles...

In the not-distant past, many people were concerned about electric lighting in the developing world. Cheap solar cells and cheap LEDs have solved that problem, permanently. In the near future, I'd expect to see the average third-world village a million miles from nowhere be lit up like New York City after dark.

Superior performance, No, it probably performs worse. But cost-effectiveness?

Salt water is free.

Why is everyone missing the point here? This is not for a geek in San Francisco, this is for someone in a remote village on an island in the Philippines that doesn't have a damn corner store to go pick up batteries at, but does have plenty of salt and water. The materials will simply survive better in this environment than traditional batteries, and need to be replenished less.

Why is this so hard to grok?

Wow, you missed the point hard. I guess I just assumed that people knew about galvanic cells... Okay, I'm sorry, let me backtrack.

The salt water has absolutely nothing at all to do with the operation of the lamp and it is not providing the electricity to operate the lamp. Salt and water are not used up or expended in the operation of the lamp. It's like the "lava" in a lava lamp. The lava isn't providing the power. It's decorative.

What is providing the power are two materials of different electronegativities, which we call a cathode and an anode. They are expended in the operation of the lamp. They are not free, are not available on remote islands, and are to be purchased - like any other batteries - from the supplier of the lamp.

Your response is exactly what the makers of this lamp are hoping for - people who don't know the science ending up believing that salt water powers this lamp, somehow. You have been deceived by their marketing.

EDIT: I responded to your one comment above without reading the rest of your comments in this thread. Had I done so, I would have been much less nice, as it is clear you are highly, highly ignorant and highly resistant to numerous people's attempts to educate you.

    Salt water is free.

Salt water is not the point. The anodes and cathodes and the LED lamp are the point.

    corner store to go pick up batteries at

The electrodes need to be replaced regularly. Where will the replacement parts come from? That problem is equivalent to having to "pick up batteries".

    The materials will simply survive better in this 
    environment than traditional batteries, and need to be 
    replenished less.

How do you know this? It doesn't say so on the website that I can see. Are you an expert on batteries (not sarcastic)? I'm not but I'm guessing a lot of engineering has gone into existing battery technology, including batteries for rugged environments and/or long term usage.

> This same lamp could simply have a wire between the carbon and zinc, with an on-off switch

Seems unlikely that there's no trade off to this, can anyone confirm? Also, it has an on-off switch.

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