Several years ago, the Samsung Galaxy Note 7 gained notoriety when its batteries caught fire in a series of accidents. There has been a steady stream of similar, though isolated, incidents since then. However, although high-level battery coverage has failed, the vast majority of Li-ion batteries are safe.
The chemical reaction that occurs inside a lithium-ion cell is complex, but as in any battery, there is a negative and a positive electrode. In lithium batteries, the negative is a lithium-carbon compound, and the negative is cobalt oxide (although many battery makers are moving away from cobalt). These two compounds cause a safe, controlled reaction and deliver power to your devices. When the reaction gets out of control, you end up with the earbuds melting in your ears. What changes a safe reaction into an uncontrolled reaction could be any number of things: excessive heat, physical damage during use, physical damage during manufacturing, or use of the wrong charger.
The three rules of thumb that have kept me safe (so far) through testing dozens and dozens of batteries are:
- Avoid cheap cords, chargers, and outlet adapters.
- Make sure the batteries are not exposed to excessive heat (more than 110°F).
- Check batteries regularly for signs of damage.
Avoiding cheap adapters, cords, and chargers is most important. These are the most likely sources of problems. Those chargers you see on Amazon for $20 cheaper than competitors? Not worth it. They may have reduced the price by reducing the use of insulation materials, leaving out power management tools, and ignoring basic electrical safety. Price alone doesn’t guarantee safety either. Buy from reputable companies and brands.
Then there is the heat. Too much of it can cause all kinds of problems, both in terms of emptying and in terms of safety. Avoid heat, and pay attention to your batteries when charging them. If your device becomes extremely hot while charging, this could be a sign of a problem. Likewise, beware of any swollen, swollen, or otherwise deformed batteries.