I regularly go running in the evening and music is the perfect companion to keep me going. After many different setups I settled on a minimal pair of Bluetooth earphones that pair to my Android Wear watch. However, after a few months of use they stopped working. The manufacturer sent me a brand new set straight away and told me to keep the original pair. This gave me a perfect opportunity to open them up and see what had gone wrong.
After opening the compartments on each earpiece I realised that the lithium battery had failed and slightly bloated up. The other side, containing the main PCB and controls, seemed fine. After de-soldering and removing the battery I temporarily attached a spare 2032 lithium cell of the same voltage to see if the earphones themselves were still functional. They were, meaning all that I needed was a tiny replacement battery. I found (after much searching) what appeared to be a similar-sized battery on eBay, one that is usually used for starting petrol powered Remote Controlled (RC) cars.
This battery only just fit inside (with some gentle persuasion) but the earphones were reassembled with no further issue and they were back in operation. Before replacing the other compartment cap I decided to try an experiment to extend their connection range: creating a longer antenna. This meant adding a small length of wire that made the final length a multiple of the original. The picture on the right is the unclipped test wire soldered onto the original PCB antenna. In the end the range did not extend by much but it did make for some interesting tests regarding antenna length, signal range and direction.