You can salvage lithium ... invest in a charger that is capable of running some capacity tests against the cell. Or if you’re a bit more adventurous, you can build this “Battery Health Monitor ...

The circuit has internal under/over-voltage ... a complete constant current/constant voltage linear charger for single cell lithium-ion and lithium-polymer ... This USB/AC Li-Ion battery charger is ...

It’s barely larger than the battery itself ... we’ll never know. The circuit on this coin cell charger is built from an MCP73831, a nice single cell, lithium ion and lithium polymer charge ...