From ElectricBike.com
There has been a boom in ebike builders making their own battery packs out of the popular 18650-format cells (18mm diameter, 65mm long), and I want to share what I’ve found out about the guts of an 18650, so you will understand more about proper DIY pack-building methods.
*Why would somebody make their own pack?*
The existing battery pack vendors will only make (and stock) the packs that they think they will sell enough of, to make it worth risking their available cash…
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