Don't charge your power bank overnight.

Charging a power bank overnight poses several risks. Photo: ACS .

Charging overnight is a highly debated topic in the tech world. While some accept it for phones with slow charging speeds, the issue with power banks is more complex.

According to Slash Gear , most power banks have a much larger capacity than phone batteries. Therefore, they also pose more risks when charging for extended periods.

High risk of fire and explosion.

As the name suggests and its main function, a power bank stores energy to recharge phones and other common devices, including headphones, smartwatches, and tablets.

Portable power banks store energy using lithium-ion or lithium-polymer batteries. When they are overcharged without proper protection, the internal chemicals can become unstable, causing overheating.

That's when the battery temperature spikes, sustaining itself in a vicious cycle of increasing heat. In fact, this is one of the main reasons lithium batteries catch fire.

The risk of fire, explosion, or damage from power banks is significantly higher than with mobile phones. Photo: Anker.

Other causes include physical damage, prolonged heat exposure, and incompatible cables. When just one of these factors combines with charging in bed or under a pillow, it can become deadly, as the heat has nowhere to dissipate.

Earlier this year, a reporter in Los Angeles had her cell phone charger explode in bed at 5 a.m., causing her chemical burns and a hole in her mattress.

Of course, not all power banks will spontaneously explode when charged overnight. But even if that doesn't happen, overcharging can cause battery cell degradation over time, reducing their capacity. When cells degrade, they tend to swell.

Is it okay to charge a power bank overnight?

Like modern smartphones, most power banks have a built-in battery management system that automatically stops consuming power when it reaches 100%. However, power banks still boast significantly larger battery capacities, sometimes up to 25,000 mAh.

Meanwhile, the average smartphone has a battery capacity of less than a quarter of this. Larger capacity means more energy reserves, higher heat dissipation, and a longer response time if a malfunction occurs.

That sounds scary. But the good news is that most reputable manufacturers say users don't need to worry too much. According to Ugreen's blog, "with advancements in technology, power banks can now be safely charged overnight."

Choose branded, safety-certified power banks. Photo: Shutterstock.

Meanwhile, Ambrane's charging guide mentions that most modern power banks have safety features, making occasional overnight charging "generally safe." However, not all brands offer this advice. Anker's safety guide recommends avoiding overnight charging altogether.

According to Slash Gear , users need to be especially careful with old or cheap power banks, as they can harm phones in several ways.

Cheap power banks often lack safety certifications, such as UL, CE, or FCC, which guarantee basic protection against overcharging and short circuits.

Additionally, before a power bank becomes dangerous to use, there will be warning signs, including swelling, a strange smell, or overheating. Stop using the device if you notice any of these signs.