With our busy lives, it’s surely not possible to keep watch over your phone every time you want to charge it with a power bank. At some point, you’ll leave the phone connected to a power bank even after it’s full. Some people have asked in the comments whether a phone battery can ‘boil over’ due to a power bank charging too long. We decided it was time to investigate whether or not it’s safe to leave a phone connected once it’s fully charged.
The reason why some people may be concerned about leaving their battery connected to a power bank is because of batteries. Yes, batteries, our favorite topic. To bring you up to speed, phones use lithium batteries which are partly made of an electrolyte solution. We previously broke it down on this blog post about lithium-ion batteries, but in short when your battery’s electrodes are plugged into a circuit, it forces the electrolyte to start transforming. The solution slowly begins changing forcing electrons to move through the circuit, and when plugged into a device, creates a charge. However, electrolytes are extremely combustible and also sensitive to temperature. The myth that batteries can ‘boil over’ is therefore derived from the battery getting too hot when no more charge can be stored. This has also led to other concerns like “is it safe to leave a phone charger plugged in?” and “is it safe to leave a phone charging overnight?”. However, the idea of a battery ‘boiling over’ isn’t correct for one reason – overcharge protection.
That idea of a battery significantly degrading due to overcharging was viable years back. This however doesn’t apply to the modern devices and power banks, at least if you use the right one.
Quality power banks feature overcharge protection. This is a form of technology that protects your phone battery from overcharging when connected to a power bank. It involves putting in place a power circuit that detects the upper limit of the terminal voltage. When the circuit realizes that your battery has reached its limit, voltage is cut off. This means that your power bank will not continue charging a full battery, averting the concern whether your phone is safe when connected to a power bank.
So What Degrades A Battery?
Though leaving a phone connected to a power bank or charging overnight doesn’t do any mentionable damage to your phone, there are other factors that can contribute to your battery having a short life span.
Charge Cycles: Every battery has a lifetime, and it is majorly affected by the charge cycles. A normal phone battery can have at least 500 charge cycles without significantly degrading. This is about 1 and a half years of use, which is more than the duration some of us use our phones. This degrading occurs because of the chemical reactions that typically occur as you charge your battery.
Temperatures: Temperatures on both ends of the spectrum normally affect the performance of a battery. Very low temperatures increase the internal resistance within a battery and lower the capacity. Extremely high temperatures on the other side can subject lithium-ion batteries to short-circuiting. These can be temperatures from the environment, or even heat from pass through charging.
It is safe to leave a phone connected to a power bank. However, you also need to take a few precautions, and especially when choosing your power bank. Some of the cheap power banks in the market can miss features like over-current protection, overcharge protection, short circuit protection, over discharge protection, or high-temperature protection. By getting a quality product, you won’t have to watch your phone as it approaches 100%, or even worry whether it’s safe to leave a phone charging for too long.