Best portable chargers (2025): iPhones, iPads, laptops and more
Many years ago, the Samsung Galaxy Note 7 gained notoriety when its batteries burst into flames in a series of incidents. Since then, similar, albeit isolated, incidents have occurred again and again. But despite the high-profile coverage of defective batteries, the vast majority of Li-ion batteries are safe.
The chemical reaction that occurs in a lithium-ion cell is complex, but like any battery, there is a negative and a positive electrode. In lithium batteries, the negative is a lithium-carbon compound and the positive is cobalt oxide (although many battery manufacturers are moving away from cobalt). These two compounds trigger a safe response when controlled and deliver energy to your devices. However, if the reaction gets out of control, the earbuds will melt in your ears. What changes a safe response to an uncontrolled response can be a number of things: excessive heat, physical damage during use, physical damage during manufacturing, or using the wrong charger.
The three basic rules that have kept me safe (so far) through testing dozens of batteries are:
- Avoid cheap cables, chargers and socket adapters.
- Make sure batteries are not exposed to excessive heat (above 110 degrees Fahrenheit).
- Check batteries regularly for signs of damage.
The most important thing is to avoid cheap socket adapters, cables and chargers. These are the most likely causes of problems. Those chargers you see on Amazon that are $20 cheaper than the competition? It’s not worth it. They likely reduced the price by skimping on insulation, foregoing energy management tools, and ignoring the basics of electrical safety. The price alone is no guarantee of safety. Buy from reputable companies and brands.
Then there is heat. Too much of it can lead to all sorts of problems, both in terms of discharge and safety. Avoid heat and pay attention to your batteries when charging. If your device becomes excessively hot while charging, this could be a sign of trouble. Also look for swollen, bulging, or otherwise deformed batteries.
