When Emily picked up an old inkjet printer from a thrift shop for less than $5, there were a lot of unknowns to explore. Most of the attention were focused on more practical items like "does it print" and "are replacement ink cartridges still available." (Yes and yes.)

Emily noticed a few mentions of battery-powered operation and recharging the battery, but this was initially dismissed as an optional capability absent from this printer because we saw no batteries. It turns out they were cleverly hidden inside the printer's platen.

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This was an impressive feat of component packaging and we admired this work briefly before turning attention to investigating battery operation. The C battery form factor is pretty rare now, but non-rechargeable Alkaline C batteries are still available cheap. Ignoring the clearly labeled "USE Ni-Cd BATTERIES ONLY" warning, Emily put some in the printer and confirmed it was not happy with those.

C-cell batteries have fallen out of favor, as has Ni-Cad batteries, so given the small market and low volume it was no surprise directly replacement C-cell Ni-Cad batteries (*) are expensive. Costing even more than C-cell NiMH batteries of far greater capacity.

As an alternative to spending money on new NiCad, I was curious if these old cells can be revived. It's impressive that after many years of neglect every cell still read 0.1V without load. If these were lithium chemistry rechargeable batteries, such low level of charge would have caused chemical damage inside the battery. A crude metaphor I've come across: the lithium battery would have starting eating itself from the inside.

But nickel-based chemistries are hardier, and there's a chance NiCad batteries can be revived even in the face of such abuse. Can these be revived? Or are they hopeless like the Neato batteries? I bought a bunch of C-cell battery holders (*) so I can connect these old cells to my battery charger. Let's see if they're willing to come back to work.

(*) Disclosure: As an Amazon Associate I earn from qualifying purchases.