Random Encounter 4: Use old battery cells as a new power source

After recelling the battery packs for the handhelds, it is important to test the capacity of those old cells. In fact, very often when a battery pack seems to be dead, it would turn out that only one or two of the cells inside the pack are depleted, while the rest are still functional.

For example, in this 10+ years old battery pack for a Fujitsu laptop, only one of these six cells no longer holds charge, while the others are still working despite their aging condition. 

So for the sake of the environment and the pocket, do not throw away the cells right away!

Those old cells, even though not ideal on the handhelds anymore, can still be put to good use to charge up other devices. One ideal solution is to put these cells in an empty powerbank box. DIY such chargers is pretty cheap, normally costing just a few bucks in USD. 

I was lazy though so I bought a readymade powerbank box for just 2 USD.

A simple parallel layout of these cells can easily give you 3,000+ mAh of capacity.

It charges devices like smartphones just fine (with slight mods it can even charge your HPC)! No need to buy brand new powerbanks anymore.