Power banks lose up to 40% of their capacity: how to determine the real power.

According to ТСН: Today, power banks are immensely popular in Ukraine due to constant power outages. When choosing these devices, most consumers rely on the volume stated by the manufacturer on the packaging, whether it is 20, 30, or 40 thousand milliamp-hours.

However, many do not realize that manufacturers often hide important information, namely that the claimed volume can significantly differ from the actual one.

Power bank capacity: declared vs nominal

Experts claim that there are two main indicators of a power bank's capacity: declared (typical) and nominal (actual).

Declared capacity means the volume measured under ideal laboratory conditions that reflects the total capacity of the lithium or lithium-polymer batteries from which the power bank is made.

Nominal (real) capacity is the amount that actually reaches your device during charging.

The difference between these indicators, unfortunately, is always not in favor of the consumer.

The reason for the loss of capacity lies in voltage conversion. The batteries inside the power bank operate at a voltage of 3.6–3.7 volts. To charge modern smartphones or tablets, at least 5 volts are needed, and sometimes even more for fast charging. To achieve this necessary voltage, a special converter is used, which transforms the output voltage of the battery (3.7 volts) into the required for charging (5 volts). This energy conversion process leads to significant losses, which can range from 30 to 40 percent.

How to determine the real capacity of a power bank

Manufacturers do not legally deceive by stating the maximum capacity of the batteries, however, it is more advantageous for them to indicate larger figures, as it looks more attractive to buyers.

In practice, this means that if the declared capacity of a power bank is 20 thousand milliamp-hours, you actually receive about 11-12 thousand milliamp-hours.

Losses depend on the quality of controllers and stabilizers, but on average, the efficiency coefficient during charging is about 65–85 percent.

Consumers should remember a simple rule: when choosing a power bank, subtract about 35 percent from the declared capacity.

What to pay attention to when choosing a power bank

When choosing a quality power bank, in addition to actual capacity, other elements ensuring safety and durability should be considered:

• A quality device should have protection against over-discharge, short circuit, and overheating, which protects it from losing its initial capacity and ensures the safety of connected devices.
• The difference in actual capacity depends on the quality of converters and charging controllers. High-quality power banks have an efficiency above 90 percent.
• For accurate determination of real capacity, special devices can be used, such as a USB multimeter, which measures how much charge is actually transferred to another device.

Today, when electricity has become a rarity, power banks have become indispensable assistants for many Ukrainians. Considering the difference between declared and actual capacity, it is important for consumers to choose products that will provide reliable charging in critical moments. Paying attention to the quality, safety, and characteristics of power banks is a necessity that can significantly impact comfort in everyday life.