Power Bank – what is it, how it works, how to use it

Modern electronic equipment is characterized by increased power consumption, which leads to an accelerated discharge of the standard battery. Portable batteries can help reduce the risk of sudden power outages. Before purchasing a device, the owner needs to find out what a power bank is, how to choose a device and how to operate it.

Principle of operation

The power bank consists of a battery installed inside a waterproof casing made of metal or plastic. The device is equipped with a controller that controls the processes of charging and discharging batteries.

The batteries are connected to a common bank in a parallel circuit, providing an increase in capacity. On the end cover there are connectors for switching external consumers and there are control LEDs that display the charge level of the built-in batteries.

The principle of operation of an external charger is based on the transfer of accumulated electricity. When the connection cable is connected, charging is activated automatically, some devices are equipped with a power button.

A protective module is installed in the design of the unit, which is triggered by a short circuit or overload. Since lithium polymer cells are sensitive to overheating, a temperature sensor is used. When the temperature rises above the permissible limit, the power bank automatically turns off.


Portable chargers are equipped with rectangular or cylindrical housings. Dimensions depend on equipment capacity. Products are available with cases that fit over the back of a smartphone. The equipment charges the battery and protects the phone case from shock if dropped.

Powerbanks differ in the type of batteries installed. There are charging blocks with lithium-ion and lithium-polymer batteries, the voltage in the charging circuit depends on the purpose of the block.

What is it for and how to use it

A mobile charger extends the battery life of smartphones, cameras or tablet computers.

The equipment maintains the operability of the electronics during a long stay outside the city.

Powerbanks with increased capacity are used to power laptops or projection equipment during training events or outdoor presentations.

After a potential buyer has found out what a power bank is, you need to familiarize yourself with the recommendations for use:

  • If the equipment was stored at negative air temperatures, then before the first use, it is necessary to warm up the product to room temperature. When heated, condensation forms on electronic components, which can cause a short circuit.
  • After initial charging, the battery must be discharged using a reduced power load. To achieve the nominal capacity, 2-3 training cycles are carried out.
  • The design of the equipment provides LED status indication, when the battery is discharged, it is required to turn off the external equipment, and then restore the capacity using an external adapter or other method.
  • When charging a power bank, you need to bring the charge level to 100%. Lithium cells installed in the charging unit do not have a pronounced “memory effect” (reversible decrease in capacity). But with constant undercharging, a decrease in performance is noted.
  • If the user does not plan to use the equipment for 2-3 months, then it is necessary to discharge the battery by 50%. When storing products with fully charged or discharged cells, degradation of the anode and cathode materials occurs. During storage, periodic checks and recharging are performed.
  • When using or storing the power bank, it is necessary to provide protection from direct sunlight or heat sources. Overheating of the case leads to a decrease in operating parameters and the failure of batteries. It is not recommended to charge at subzero temperatures (due to reduced efficiency of power supplies).

It is forbidden to destroy the case of the power bank or operate the device with visible external damage.

What to look for when choosing

When choosing a portable battery for charging electronic devices, the following parameters are taken into account:

  • battery capacity (determines charging capabilities);
  • type of power supplies (affects weight and battery life);
  • configuration and dimensions of the case (determine the way of carrying);
  • the number and type of ports for switching external equipment;
  • the rate of recovery of the capacity of the bank;
  • additional functions.

Battery Type

Lithium-ion devices are characterized by high energy consumption and low self-discharge.

The design of the batteries does not allow mechanical damage and violation of the charging conditions. The devices do not allow deep discharge and charging with increased voltage; during long-term storage, the elements lose their characteristics.

Lithium polymer cells have an increased capacity and an extended operating temperature range.

The disadvantage of the products is the increased sensitivity to overheating; if the temperature rises, the battery may catch fire. Electronic controllers are used to prevent fire.


The capacity of the accumulators built into the power bank allows you to assess the capabilities of the equipment. Before buying a power source, you need to determine what the power bank is for.

If the product is to be used for periodic charging of a smartphone, then a capacity of up to 10,000 mAh is sufficient.

Devices for maintaining the operation of a tablet computer or laptop have a capacity of up to 50,000 mAh. With increasing capacity, the weight and dimensions of the battery increase:

Equipment with a capacity of up to 10,000 mAh is designed to restore the battery level of mobile phones and smartphones. The advantage of the products is the size and weight. The device is carried in a pocket of outerwear or a woman’s purse. When switching, compare the capacity of the external unit and the parameters of the rechargeable battery. To ensure operability and reduce the risk of overheating, the battery capacity of the power bank should exceed the phone battery capacity by 250-300%.

To service the batteries of entry-level smartphones or tablet computers equipped with power supplies with a capacity of 3000-4000 mAh, power banks with an increased capacity of up to 20,000 mAh are used. The equipment is not intended for carrying in pockets, since the weight reaches 450-500 g. The devices are stored in bags, some of the devices are equipped with standard carrying cases.

An external power supply with a capacity of more than 25,000 mAh is required to charge the laptop battery. An example of such equipment is the Power Bank K2 block from Powerplant. The equipment is equipped with a metal protective case, which provides additional cooling of the components. Due to the installation of high-capacity batteries, the weight of the device has reached 1.2 kg, a special container is required for carrying.

Current strength

Powerbank devices are divided into 3 categories:

  1. Accumulators providing amperage in the circuit up to 1 A. Chargers are designed to restore the capacity of batteries in standard cell phones. Powerbanks with such parameters are rare.
  2. Charging units designed for a current of 1.5-2.0 A. The design of the equipment is designed to service power supplies for smartphones and small-sized tablets.
  3. Products that support the current in the output circuit from 2 to 4 A. Due to the increased power, it is possible to charge the batteries of tablet computers or several smartphones at the same time. It should be borne in mind that charge current limiters are used in the design of electronic equipment. Some units are equipped with mechanical switches to adjust the parameters of the charging current.

Charging method

To restore the capacity of a portable battery, 4 methods are used:

  1. Using a cable that connects to the USB connector of a home computer or laptop. The disadvantage of this method is the reduced current in the charging circuit (design limitation), which leads to an increase in the recovery time of the battery.
  2. By means of a power adapter connected to a 220 V AC outlet. To restore devices with a capacity of 4-5 thousand mAh, it is allowed to use standard blocks from cell phones (supporting a charging current within 1 A). When charging products with a capacity of more than 5 thousand mAh, you must use special adapters designed for a current of 2-2.5 A.
  3. With the built-in solar battery (located on the front of the unit casing). The method is suitable only for compensating for a part of the consumed energy; full recovery of the battery with the help of photocells is difficult.
  4. From the on-board network of the car, a special charging unit is used for switching. The plug is connected to an additional socket or cigarette lighter socket, the process of restoring capacity is identical to charging from a household network.

The equipment is designed with control indicators that show the progress of the charging procedure. The electronic controller automatically adjusts the charging current, when the standard battery capacity is reached, the power is turned off.

If there is an accelerated discharge of the battery (when using a standard load), then 3-4 training cycles are performed to restore normal operating parameters.


Basic versions of the power bank use 1 USB standard connector for connecting external devices. Depending on the power of the device, the plug is designed for a current of 1 or 2 A.

On some models, 2 or 3 USB ports are used, allowing you to connect multiple devices at the same time. When using synchronous switching, the current in the circuit increases, which leads to an accelerated discharge of the external unit.

There is equipment with a USB Type C connector for connecting mobile equipment. Devices with increased capacity are equipped with round plugs (for connecting laptops).

Some of the powerbank modifications are supplied with a set of adapters for charging laptop computers from various manufacturers.

An additional micro USB connector, provided on all external batteries, is designed to connect the power adapter.

Other parameters

Additional functions and characteristics of external batteries:

  • the presence of a module for wireless charging;
  • installation of auxiliary elements (for example, brackets for wearing or small-sized LED lights);
  • dimensions of the case and weight of the charger.

When buying an external power supply, the manufacturer is an important criterion. The equipment assembled by factories of large companies is distinguished by the use of high-quality batteries and electronic components. Small manufacturers use simplified components and claim inflated performance. It is not recommended to purchase such products, the money saved will be spent on repairing or upgrading the device.