(Disclaimer: if you solder batteries, be very careful and do not solder directly to the battery. They can explode and cause you harm!)

Many electronic devices have rechargeable batteries in them and they are not easy to replace. Usually, the batteries are just standard AA or AAA batteries, but soldered directly to the electronics.

My Phillishave hasn't performed well for some time. I finally took some time out last night to fix it. The good news is it comes apart very easily. I took it apart a couple of weeks ago and found that it used a single AA rechargeable battery. The battery was stuck to the board and soldered in with lots of solder.

With a bit of patience these batteries can be swapped out and I needed a lot of patience because of the way the battery tabs were attached to the little circuit board.

The main body of the shaver comes apart with three screws, but you will need a star screwdriver head. My pry kit comes with the right screwdriver. One of the screws is under the trimmer switch. But this is easy. Some electronics hide the screws more and you may need to remove some plugs in order to get at them. I had to do this with my trimmer last year.

I took photographs as I disassembled the shaver. I knew it would be a couple of weeks between opening it and fixing it, so it's a good way of documenting what goes where for reassembly later on.

The shaver consists of a small circuit board attached to a motor which is attached to the shaver heads. It was a good opportunity to clear the shaver out. You would not believe the amount of debris that was in the shaver, but let's just say I will never use a second-hand one...

The orange battery is pictured and replacements are easy to get. The board comes out very easily and the two screws either side of the motor release the shaver head. This can be disassembled and cleaned, but be careful not to lose the springs. I desoldered the motor to make it easier to work on the board.

It took me 30 minutes to desolder the battery. Whether this had been soldered by machine or human, they'd put loads of solder on it and there was solder under the tabs as well. It took me four attempts to desolder with a desoldering pump, but eventually I was able to release the battery contacts. I had to cut them off the battery.

There was a bit of glue under the battery but it rocked off the board quite easily.

The battery contacts needed to be trimmed to fit through the holes on the board. I then soldered it on. The joints were clean enough to work. I'm still a beginner at soldering but this was good enough. The wires went back onto the motor easily and the motor worked. The battery had charge in it.

I reassembled the device and it charged perfectly. I was worried that I hadn't reconnected everything properly, but I obviously did. The shaver will last me another five years and I can always repeat the procedure again, if I want to.