Best Portable Chargers (2025): iPhones, iPads, Laptops & More

Many years ago, the Samsung Galaxy Note 7 became infamous after its battery caught fire in a series of incidents. Since then, similar but isolated incidents have continued to occur. However, despite high-profile reports of battery problems, the vast majority of lithium-ion batteries are safe.

The chemical reactions that occur inside a lithium-ion battery are complex, but like any battery, there is a negative and a positive electrode. In lithium batteries, the negative electrode is lithium carbon compound and the positive electrode is cobalt oxide (although many battery manufacturers are moving away from using cobalt). These two compounds cause a safe reaction under control and provide energy to your device. However, when the response gets out of hand, you’ll eventually find the earbuds melting in your ears. There are many factors that can change a safe reaction to an uncontrolled reaction: overheating, physical damage during use, physical damage during manufacturing or using the wrong charger.

After testing dozens of batteries, the three basic rules that have kept me safe (so far) are:

1. Avoid cheap power cords, chargers, and outlet adapters.
2. Make sure the battery is not exposed to excessive heat (above 110 degrees Fahrenheit).
3. Check the battery regularly for signs of damage.

Avoiding cheap wall outlet adapters, power cords and chargers is most important. These are the most likely sources of your problems. Those chargers you see on Amazon that are $20 cheaper than the competition? Not worth it. They may lower the price by reducing insulation, omitting power management tools, and ignoring the basics of electrical safety. Price itself doesn’t guarantee safety, either. Buy from reputable companies and brands.

Then there’s the heat. Too much can cause all kinds of problems, both in terms of emissions and safety. Avoid heat and pay attention to the battery when charging. If your device becomes overheated while charging, this could be a sign of a problem. Likewise, be aware of any swelling, bulges, or other battery abnormalities.