Introduction
Lithium-ion battery is a dangerous battery.
Please understand the danger of the lithium-ion battery in advance, and disassemble and use it at your own risk.
The battery pack of an electrically assisted bicycle often contains an 18650 lithium-ion battery.
The 18650 that can be used again is often contained in the battery packs that are sold as junk items.
The battery that I disassembled this time seems to have deteriorated to some extent, but it contained 21 usable 18650 lithium-ion batteries.
I bought the battery pack for about 5$, so it costs about 0.24$ per battery.