My Projects

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Published 31 Mar 2018

Sort Batteries

The proposal is for a machine to help recycle domestic batteries by sorting them into Zinc/Carbon, Alkaline, Lithium, Nicad, Ni-Mh categories and with a theme of sustainability/recycling the machine discharges any cells that have residual charge into the machine to power it.

It could also assess the health of cells to decide whether they were actually near new and should be re-used rather than recycled, especially expensive rechargeable cells.

I am thinking here of A, AA, AAA, B, C, D type cylindrical cells that can all be handled in a similar way. I am envisaging a simple mechanism mechanically that has a feeder/hopper into which cells are dumped, they then roll down a chute one by one, and they are scanned as they rotate, to read their labels. Any unidentified cells go into a separate output bin. Identification could be through OCR and text matching or image pattern matching of the entire label. There would need to be an initial 'training' period.

Implementation notes

  • I am thinking of minimal complexity hardware, and all the work done by software. So the mechanism would just be required to release one cell at a time down a chute, in either polarity orientation (ie it wouldn't worry about which end was which). So the rest of the system would handle cells either way around with regard to positive/negative terminals.
  • The feeder mechanism can measure the diameter of the cell to assist with scanning the label around the circumference. Probably the easiest way to measure diameter is with a lever arm that the battery passes under.
  • There is perhaps no logical start/end to labels apart from the seam
  • The scanning could be done with a linear CCD sensor synced to the battery being rotated, like the old document hand scanners that used a roller to clock the scanner as it was moved across a page.
  • Voltage/discharge characteristics could be used for identification, but difficult due to the unknown state of the cells.
  • Charging characteristics would be dangerous to assess unless the cell was already determined to be rechargeable
  • Pre sorting of leaking batteries would be required as wouldn't want leaking battery material throughout the machine. Perhaps liquid or stains on the battery label could be detected.
  • To measure battery health, and discharge batteries a connection needs to be made to either end, with some batteries there needs to be significant pressure (eg a spring) pressing the contact onto the battery to ensure the end-caps contact the internal anode/cathodes properly. Might need some sort of battery terminal clamp that is opened momentarily to admit the battery, battery contacts can be automatically centred with a lever that adjust for hieght (diameter) of the battery.

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