In case it wasn’t obvious, my ambition to revive some old NiCad C batteries is more for curiosity than any practical reason. Yes, replacement would cost a few bucks, but hardly breaking the bank. In fact the C cell battery holders I bought to help charge them cost about half the cost of the battery cell, so I definitely can’t hide behind cost saving as an excuse.

Buying replacements isn’t the only thing we can try, either. I was amused when I learned that battery size adapters existed. Apparently, modern NiMH rechargeable batteries in AA form factor can meet electrical demands that formerly required C or D cell alkaline batteries, so it’s possible to put those NiMH AA cells into a sleeve that helps them fit into space designed for C or D cells.

Far from an unauthorized use or hack, such adapters are occasionally bundled along with batteries as seen at my neighborhood Costco. This pack of Energizer branded NiMH rechargeable cells are bundled with four AA to C adapters, and four AA to D adapters.

Inconveniently (or possibly simply a result of Murphy’s Law) Emily’s printer takes five batteries, and there are only four adapters of each size. This is irritating not just because of the current project, but that there are six AA NiMH batteries in this package. Thus they did not include enough adapters to use all six AA batteries…. nor would six batteries be enough to fill all eight adapters. It’s the hot dog & hot dog bun packaging issue all over again, except this mismatch is in the same package!

Back to the adapters: D-cell adapters have a physical electrical connection, as D cells are slightly longer than AA batteries. However, C cells are roughly the same length, so the AA to C adapter is a passive plastic sleeve with a hollow center and no electrical connection. This makes me think we can 3D print a few for experiment’s sake. And as Randy Glenn commented on yesterday’s entry, people have already uploaded adapters to Thingiverse, and modified versions thereof, to help people do exactly that.

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.

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.