Recycle Old Almost Used Alcaline Batteries

This project aims to get rid of a lot of under voltage alcaline batteries(any battery will do) that you can't use because they're half empty but you're reluctant to throw away because they're half full.

You will need of course a lot of half used batteries ant the standard equipment, cardboard, hot glue, soldering iron, cables, nuts&bolts etc.

The idea is to group together the batteries and drain with a boost circuit as much as possible of the residual charge(an evolved version of the joule thief).

To keep the batteries aligned, simply make a "V" with the cardboard, at the end on the positive pole, use something flat and conductive(I recycled an old copper board, so it is possible to solder directly on it), on the negative side I've used a spring, tensioning a screw with a wire twisted and soldered around it.

More details on picture.

This is a very simple schematic, for the series/parallel just invert the load/source following this instructable:

https://www.instructables.com/SIMPLE-ParallelSerie...

Then attach our load which is the boost circuit(e.g.mt3608 or cheapest alternative) and following the output, in my case an usb port for small loads(don't expect to charge a modern smartphone) and with an additional switch the carger for the lipo battery, so I can transfer the residual charge and put it to good use instead of letting it go wasted over time.

BATT -> Switch S/P -> Boost -> usb/lipo

p.s. don't forget to set the correct output voltage 5.2-5.4v should be fine in most cases