Many years ago, the Samsung Galaxy Note 7 caused a scandal when its battery caught fire in a series of incidents. Since then, there has been a steady stream of similar, albeit isolated, incidents. However, despite the battery coverage problems, the majority of Li-ion batteries are safe.
The chemical reactions that occur inside lithium-ion batteries are complex, but like any battery, there are negative and positive electrodes. In lithium batteries, the cathode is a lithium-carbon compound and the anode is cobalt oxide (although many battery manufacturers are phasing out cobalt). These two compounds cause a safe reaction when controlled and powering your device. However, when the reaction gets out of control, you will find the headphones melting in your ears. What alters a safe reaction from an uncontrolled reaction can be any number of reasons: excessive temperature, physical damage during use, physical damage during manufacturing, or Using the wrong charger.
The three basic rules that have kept me safe (so far) when testing dozens of batteries are:
- Avoid using cheap cords, chargers, and outlet adapters.
- Make sure the battery is not exposed to excessive heat (above 110 degrees F).
- Regularly check the battery for signs of damage.
The most important thing is to avoid cheap wall outlet adapters, cords, and chargers. This may be the source of the problem. Those chargers you see on Amazon that are $20 cheaper than the competition? It's not worth it. Perhaps they cut prices by skimping on insulation, ditching power management tools, and ignoring the basics of electrical safety. Price alone does not guarantee safety. Buy from reputable companies and brands.
Then there's the heat. Too much of it can cause all kinds of problems, both in terms of discharge and safety. Avoid high temperatures and pay attention to the battery when charging. If your device gets too hot while charging, this could be a sign of a problem. Likewise, be careful of any batteries that are swollen, bulging, or deformed.