Is there a cable from my (old) macbook 4-pin power-input to USB?

I aske because there are a few portable batterypacks out there, which could give just enough juice. But they all work with an USB connection, since they were built with charging smartphones/tablets in mind. Is it actually possible?
Thanx if you can help me out there.

Apple 30-pin to USB Cable

Apple 30-pin to USB Cable

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