Protection Mechanism for Power Banks

Table of Contents

The incidents related to lithium batteries are going up every year, according to the FAA’s data. As the most widely used item about lithium batteries, power banks need to be done with the proper protection mechanisms. Or it will be unsafe to use.

Let’s explore this subject further today.

Short Circuit Protection

In batteries, a short circuit happens when the positive electrode connects to the negative electrode directly. It heats the battery rapidly and may cause fire or explore. 

The power bank short circuit protection is designed to prevent bad things from happening. It keeps detecting the current and will switch the circuit to higher resistance if the current reaches a high value. Or even cut off the circuit if the current cannot be dropped off.

Overcharge Protection

Overcharge is charging the battery over its capacity. It is related to 3 things: voltage, current, and temperature. Each of them can cause overload, then degrade the battery. 

If the battery is overcharged for a long time, it will create an explosive gas that combines hydrogen and oxygen. After building up to intense pressure, it will break the battery housing. Like the short circuit, the battery will get too much internal heat and be dangerous to handle.

To avoid this condition, people design overcharge protection. When the battery is fully charged, the charging process stops. It means that you do not need to worry about any issues if you leave your power bank charging overnight.

Over-discharge Protection

Over-discharge is the same as deep discharge. 

Generally, the lithium-ion battery should not be discharged under 2.5V to 3V. It could potentially cause copper plating and an internal short circuit if over-discharge under 2.4V. Because there is a copper collector on the anode, and it will become electron-deficient when the discharge voltage is too low. Then the copper can dissolve into the electrolyte and reform as copper. 

The over-discharge protection is made for checking the battery voltage. If the voltage is too low, it will turn off the circuit. 

Most manufacturers are done with the solution of diodes. Because it is cheap and has a few components needed. The circuit will run if the voltage reaches the diode level. Or not, it will stop.


For safety concerns, almost all factories are doing power banks with protection mechanisms. However, some small factories settle on quality with low prices to win the orders. It is not only bad for the market but also leads to more incidents. 

Hi, I’m Ryan Gao, a father of 2 kids, also the content manager of I’ve been working on consumer electronics for 8 years now. On this site, I like to share with you the knowledge related to power banks, wireless headphones, and portable power stations from a Chinese supplier’s perspective.

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