Making Electricity From Apocalyptic Scrap

I mentioned my desire to see how practical is was to make thermocouple for generating electricity.   So what scrap metals will i find in Mad Max world?

I started with a piece steel angle and a copper wire.  I stripped insulation from the end to get a pretty solid contract on the steel.  It does not need any insulation.   A copper bar in full contact with the steel works just fine.  Perhaps better with more opportunities for a solid connection. 

The copper strands are wrapped around the steel not very tightly.  I may try using a soldered connection next time.  The voltmeter lead is literally just lying on the steel and the other lead has the other end of the copper wire wrapped around it pretty securely. 

In shade, I was getting .1 millivolts. 

When I moved the junction into direct sunlight it went to .2 millivolts and stayed there.  Then I took a 5.5' lens leftover from a 1970s aerospace project that I have been lugging around for 50 years and focused the Sun on the junction point. A solid .3 millivolts. 

I tried this with the copper wire and a piece of aluminum rod.  This showed zero current in shade and only .1 millivolts in sunlight with magnifying lens.  I would expect the copper/aluminum junction to be more effective than copper and steel based on elextronegativity numbers for copper, iron, and aluminum.  Aluminum, however; produces a strong oxide coating as soon as it is exposed.   I may not be getting much of a voltage because of that.   I have ordered a small copper rod for further experiments. 

Okay you are going to need a lot of cells to produce a useful voltage for recharging, but while waiting for civilization to come back up you will have time.  Unlike PV panels, many of which I expect will be EMP fried, this is as simple as it gets.