I saw this in a magazine, and it caught my eye. Supposably after only 2 minutes of winding, you can charge a cell phone battery to last about 6 minutes. It does make mention that this should be used BEFORE the battery goes dead, as it takes exponentially longer to bring a dead battery back.

I emailed them and asked about a 12V version for us emergency amateur radio operators (and maybe those using commercial radios). They said they are working on developing another model that should fit this need.
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