Good and even branded hair trimmers such as Remington are relatively cheap such that they can be replaced once the batteries inside have been dried out which seems to be the intended usage. The Remington HC363C for example does not even have a trap door to be able to swap out batteries.

When the trimmer / clipper is dismantled, two lithium batteries are found on the inside that are soldered in series and connected directly to the PCB of the trimmer. From what can be determined, the PCB contains a regulator for charging the batteries and a control circuit via a switch for turning the trimmer on and off. Similarly, the whole trimmer is rated at digital levels with the charger also being rated at , such that working with the circuitry on the inside is relatively easy.

So, the process of getting the trimmer working again involves opening up the case, replacing the batteries and then closing the case back up again.

• 18650 Lithium battery, rated at 3.3V

Opening up the Remington reveals two AAA batteries that care coupled in series by being soldered together that float on the inside of the Remington. Disconnecting the AAA batteries involves desoldering the wires that connect them to the PCB but after that the can be just lifted and tossed away.

Initially, the idea was to follow the original design and, as pictured, to replace the blue Remington AAA batteries with AAA counterparts with the exact same size. Replacing the batteries was done by using some conventional AAA batteries and then using some copper wire to connect the contacts on one end, and then connect the wires on the other side at the terminals on the other end in order to achieve a total of that powers the motor.

After a short test, with the case open, it seems that the Remington is successfully repaired, due to the motor engaging and the charger lighting up the LED on the PCB when connected to the trimmer.

However, after closing the case, it was noticed that the trimmer did not start up when using the power button to turn the Remington on. After some investigation, it turned out that while the AAA batteries are sufficient in terms of voltage and total capacity, the discharge rate does not seem suitable to drive the motor. Power motors does not only require a lot of power, as a total product of amperage and voltage, but also the instantaneous drain capacity of the batteries is important. Another interesting feature is that motors generally do not have an involved circuit and consist in just a coil that can be overclocked slightly by increasing the voltage.

That being said, an 18650 vaping battery rated at was purchased and the Remington was opened up again to fit the battery. The first problem is that the Remington chassis is really designed only for two AAA batteries but the bottom case can be modified to sand down some of the support struts that are meant to hold the batteries.

Using a Dremel, with a small grinding head, the horizontal support struts for the batteries are eliminated, thereby making room for the very large 18650 vaping battery. Now fitting the battery inside the case works well and the screws can be placed back to fix the PCB.

Assembling the trimmer back again and then attempting to start the trimmer without the charger now seems to work perfectly, as well as having made the Remington HC363C powerful enough to shave an entire mob of sheep, or your pet llama, if necessary. And, we're not even kidding, it seems that the coupled with the high discharge rate of the 18650 battery, makes the Remington oscillate much faster, moving the front teeth much faster and thereby reducing the probability that the Remington will clip hairs or pull them instead of cutting them properly. A mod, that makes the object better than the original!

Further work would include adding an ESP-01 chip inside the trimmer in order to make the trimmer wireless and broadcast the battery level to an MQTT bus. Even if it seems a fad, one of the reasons that the Remington used in this page died, was that it was not charged for a long while and the batteries dried up. Leveraging some IoT and emitting the battery voltage to a centralized server, could help the user remember that the Remington needs to be charged (perhaps even with an audible alarm).