Charging a power bank overnight may seem convenient, but it hides significant risks that can arise from using poor-quality devices or older models. In particular, users should be careful, as even the most innocent habits can lead to serious consequences.
Charging a power bank overnight may seem like a very practical solution, especially when your daily routine is... life requires quick and easy access to charge our portable devices. However, there are important factors to consider, as users often overlook the risks involved, especially when it comes to cheaper or older devices.
The problem starts with the battery chemistry
Most power banks operate with lithium cells, which fall into two main categories: lithium-ion and lithium-polymer. When these batteries If batteries are left in a state of charge beyond 100% without the proper protection mechanisms, they begin to chemically decompose. This leads to the dangerous condition known as “thermal runaway,” where the temperature rise is caused by a self-sustaining reaction that is very difficult to control.
This situation is exacerbated in enclosed environments where heat cannot dissipate freely, such as when the device is charging on a bed or under a pillow. For example, in 2026, a journalist in Los Angeles witnessed an extremely dangerous situation when his power bank exploded at 5 am, leaving him with chemical burns and damaging his bed.
Even if an explosion does not occur, prolonged overcharging leads to gradual deterioration of the battery cells, resulting in a reduction in their capacity and the appearance of swelling — a clear sign of battery damage. Therefore, awareness of the risks is of utmost importance.
Which power banks are safer — and which aren't?
The main risk is found in older or cheap devices that do not have safety certifications such as UL, CE or FCC. Without these certifications, there is no guarantee that the power bank will stop drawing current once it reaches 100% charge. In addition, larger capacity power banks, such as those with 25,000mAh, are capable of storing significantly more energy compared to a mobile phone, which means the potential for heat build-up and fire risk may be much greater in the event of a fault.
If you notice swelling, an unusual odor, or excessive heat while using the power bank, it is important to stop using it immediately and dispose of it safely.
Our opinion on Techblog
The rule of thumb to remember is this: if you have a power bank from a reputable brand that carries certifications and has an advanced battery management system (BMS), the risks of overnight charging are significantly lower. However, if the device is cheap or remains of uncertain origin — especially if it is charged in bed — the risks increase dramatically. For the Greek user who often chooses cheap options from online stores, this is a critical consideration before leaving the power bank charging overnight on the bedside table. Learn more about battery and power bank safety at [Consumer Reports](https://www.consumerreports.org), and never underestimate the dangers of overcharging.
