Thai soymilk company Vitamilk has rolled out a rather interesting advertising vehicle in the form of a large signboard dubbed that takes batteries that are at the end of their working life and squeezes enough extra power out of them to charge smartphones. The company is using this "Dead batteries for Dead Batteries" campaign to (rather obscurely) promote the people-powering attributes of its product, but the part we find interesting is how it highlights our lingering indifference to wasted energy in the consumer electronics age.

The argument is that each battery that is thrown away has about 400 mAh of power remaining. After all, most users throw away a battery as soon as the device it is powering starts to show signs of not working properly. This, of course, translates to wasted energy, which is never a good thing.

Created for Vitamilk by BBDO Proximity Thailand, the signboard allows passersby to donate used batteries and give them a new purpose before they are (hopefully) recycled or (more likely) consigned to landfill. It can hold up to 1,500 batteries, which translates to about 150,000 mAh of power, or enough to fully-charge 140 smartphones.

In the two months the board has been in use, the dead battery bank has apparently given out an estimated 3,328 hours of talk time to phone users.

Check out Vitamilk's promo video below to see the battery wall in action.

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