My hair trimmer wouldn’t hold a charge, so I did a simple re-wire to run it right from the adaptor.
A lot of devices today tend to be designed as cordless. The problem is that batteries will deteriorate over time and are often the first thing to go on a product. My trimmer was a good example of this; after only a few years it wouldn’t hold a charge with enough power for more than a few minutes of operation. Plugging in the adaptor would not help, because it was designed to only charge the battery, not power the motor.
Since the battery voltage was the same as the adaptor’s output voltage (the 2.4V output on the charger matched up with two regular 1.2V NiMH batteries in series) it was possible to just cut out the batteries and run the motor right from the charger.
The trimmer is now no longer cordless, but I now get full power all the time without needing to worry about charging it. Click through the gallery to see the steps.