DIY lithium powerbanks
Posted: Mon Jan 14, 2019 8:15 am
My journey down the LIPO rabbit hole continues.
This is a 2-cell version of the single 18650 "power rod" powerbanks sold in vending machines in airports everywhere. In this case, the two cells are wired in parallel so if one cell dies, the bank will still work. Since I'm giving these to family, I'm only using top-shelf old-stock new cells that I test beforehand (old-stock new cells are harvested from laptop batteries that never get sold - eventually, that stock has to be liquidated or recycled). The circuit board limits total current to 3.1 amps; it also steps up the voltage from the ~3.6 volt range produced by the 18650 and handles (via the micro USB port between the two USB charging ports) recharging the cells.
Materials costs:
Controller circuit board: $4
Samsung/LG/other "premium" reclaimed 18650 cells: $2
Miscellaneous (3D printer filament, screws, flux, solder, wire, wire connectors): $1
I'm never going to save my way to wealth and fame by making these myself, but the few I've given away have been very well received - it seems like the combination of "handmade" and "reasonably useful" works.
This is a 2-cell version of the single 18650 "power rod" powerbanks sold in vending machines in airports everywhere. In this case, the two cells are wired in parallel so if one cell dies, the bank will still work. Since I'm giving these to family, I'm only using top-shelf old-stock new cells that I test beforehand (old-stock new cells are harvested from laptop batteries that never get sold - eventually, that stock has to be liquidated or recycled). The circuit board limits total current to 3.1 amps; it also steps up the voltage from the ~3.6 volt range produced by the 18650 and handles (via the micro USB port between the two USB charging ports) recharging the cells.
Materials costs:
Controller circuit board: $4
Samsung/LG/other "premium" reclaimed 18650 cells: $2
Miscellaneous (3D printer filament, screws, flux, solder, wire, wire connectors): $1
I'm never going to save my way to wealth and fame by making these myself, but the few I've given away have been very well received - it seems like the combination of "handmade" and "reasonably useful" works.
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