Here at Ecotech Services we like the idea of repurposing stuff as a way of stopping it going to the landfill but it seems that in most cases it is not something that makes us any money. For example take a look at this Sony DCC-E455A mobile phone charger that came in for recycling.
It puts out 4.5V at 500mA so it can be repurposed as a charger for newer phones. It looks like the maximum current on USB 2.0 is 500mA. So all that is needed is to look up the data on the chip (a JRC 2360AD), figure out how to change the voltage to 5V (a simple matter of putting a suitable resistor in the output voltage sensing circuit), and then fit a Micro B USB plug.
So lets do a costing for the repurposing:
USB 2.0 Micro B plug $3.76 Resistor $1.00 Labour $34.50 ----------------------------- TOTAL $39.26 (New Zealand dollars)
You can buy a new car charger for about $5 (although it would not be the same quality as the Sony product) so quite obviously repurposing is not a commercially viable option. Also, this particular charger has the two halves welded together so it needed to be prised apart. It would need to be glued back together after the modification. This would make it a very unprofessional repurposing job.
Another way it can be repurposed is to just use the circuit board itself as a DC-DC converter embedded into a piece of equipment. It does not have to be a 12V input voltage because the 2360 chip can accept up to 40V, although a 35V electrolytic capacitor is used on the input. There may be other design considerations when running on a higher voltage such as the power dissipation by the chip.
The conclusion for repurposing in this case? Obviously not commercially viable but something the DIYer or hardware hacker could do.