I have a set of retired hair clippers on the teardown to-do list. My hair are like bristles in a stiff wire brush, and wears down cutting blades quickly, fresh clippers only keep their "oh wow, this cuts nice" feeling for the first half-dozen or so sessions. I use one for a few years until its rechargeable battery degrades. By that point, its blades are dulled enough to be tugging and pulling hair while cutting. Between the battery and the blade, it was time for a new one.

I've been avoiding these teardowns because I knew it would get messy, given the short fragments of hair clinging to every surface of these clippers via either lubrication oil or static electricity. I knew I will find small pieces of hair everywhere for weeks after each teardown. But the paper liner on my workbench is starting to get dirty enough for replacement, and I saw an opportunity: I can do these messy teardowns and throw away the liner, hopefully easing cleanup.

First up is the Conair HC318R. Information embossed on the back of the device was hard to photograph, but it says:

(C) CONAIR CORPORATION, EAST WINDSOR
NJ 08520 / GLENDALE, AZ 85307
MODEL HC318R 4.5V DC 1000mA
USE WITH ADAPTER CA12
MADE IN CHINA
HOTLINE 1-800-3-CONAIR

Next to this information is a small tag informing me the device contains nickel-cadmium battery and must be recycled or disposed of properly. I expect to find three cells wired in series given the 4.5V DC written on the device.

If somebody has the clipper but not the charger, here are the specifications on its label. The charging port looks to be a pretty standard barrel jack wired to be center-positive.

There were two very large and easily accessible Philips-head screws on the blade. Removing them frees the outer blade, allowing us to clean inside.

The inner blade lifts away to expose the motor-driven crank.

Opening the enclosure allows a look inside.

Behind the motor sat the expected three-cell nickel-cadmium battery pack, each cell is the size of an AA battery.

There were no further fasteners holding the working bits in place. Once the enclosure was opened, the electrical guts are easily lifted out.

The battery pack manufacturer is BYD, the battery company that grew into an automotive manufacturing conglomerate. I measured less than 2V across its terminals, so it's either severely discharged or there's a dead cell in the pack. Neither would be a surprise after years of use followed by more years of waiting for teardown.

Thanks to decades of manufacturing at scale, nickel-cadmium batteries are cheap. They are also hardy and tolerant of abuse, which cut costs further because they don't need sophisticated battery management electronics like lithium-based batteries do. Here we have just a small single-layer circuit board housing the power switch, two resistors, two diodes, and one light-emitting diode. M+ (motor positive) is connected to one side of the switch opposite B+ (battery positive). M- location was unused: it had a short trace to diode D3 which was also absent. Motor negative was wired to battery negative off board then a single wire led to B- on this board, which was electrically connected to the other end of the absent diode D3. Apparently, they decided D3 was unnecessary! Finally, L+/L- lead to the AC adapter barrel jack for charging.

The motor is marked with 222C3V6 3760 but I didn't find much from that information. The crank is a piece of friction-fit plastic and slid off unexpectedly easily. The motor mount was installed with two small Philips-head screws and easily removed.

The barrel jack will stay with the AC adapter for possible future reuse. The motor will join many other salvaged motors. The battery pack will go in the nickel-cadmium battery recycle bag. The circuit board will go into the electronic recycle box. Metal blade and fasteners will go into metal recycle bin. Remaining plastic enclosure bits will go into landfill along with many bits of hair. I didn't put too much effort into cleaning the workbench, because I had more hair clippers for teardown.