Why We Use mAh Not Watts for Measuring the Capacity of Power Banks

Power banks, a critical technology for a gadgets-filled world, are rated in milliampere-hours (mAh) for a specific reason. While watt-hours (Wh) can also indicate energy content, mAh offers a more straightforward and familiar unit for consumers. In this article, we explore the benefits and limitations of using mAh as the primary unit for expressing power bank capacity.

Simplicity and Familiarity

Consumers are often more accustomed to seeing battery capacities expressed in milliampere-hours (mAh) when it comes to portable devices, such as smartphones. This familiarity makes it easier for users to understand and compare the capacities of different power banks. When shopping for a power bank, consumers can quickly grasp the meaning of a 20000 mAh power bank without needing to calculate watt-hours or consider voltage differences.

Direct Relation to Device Usage

mAh directly indicates how long a power bank can supply a certain current to a device. For example, a 10000 mAh power bank can theoretically supply 1000 mA (1A) for 10 hours or 500 mA (0.5A) for 20 hours. This direct correlation helps users gauge how long they can expect to charge their devices. Users can make informed decisions based on their charging needs, as the mAh value provides a clear and immediate understanding of the power bank's capacity.

Standardization

Many rechargeable batteries, particularly lithium-ion batteries, are rated in mAh. Since power banks typically use these types of batteries, maintaining the same unit of measurement (mAh) for capacity standardizes the industry. This standardization simplifies the process of comparing different power banks and ensures users are aware of the consistent units they are dealing with.

Voltage Variability

Power banks operate at different output voltages, such as 5V, 9V, and 12V. While watt-hours (Wh) provide a more comprehensive measure of energy (energy voltage × current), the variation in voltage can complicate comparisons if expressed in Wh. Using mAh allows users to focus on the current capacity without needing to factor in voltage differences. This simplification is particularly beneficial for casual users who prioritize ease of understanding over precise technical specifications.

Marketing

From a marketing perspective, using mAh as the primary unit can be more visually appealing in advertisements and product descriptions. Larger mAh numbers, like 20000 mAh, can create an impression of greater power compared to a smaller Wh figure. This can be an effective strategy to highlight the capacity and impress potential buyers with the power bank's ability to deliver current over extended periods.

However, it's important to note that watt-hours (Wh) can provide a better measure of the actual energy stored in a power bank, particularly when comparing units with different voltage outputs. To convert mAh to Wh, you can use the formula:

Conversion Formula

Watt-hours (Wh) (mAh × Voltage) / 1000

This conversion is useful for more technical comparisons, especially when considering the true energy content of the power bank. While mAh focuses on the current delivery, Wh provides a more comprehensive view of the energy capacity, considering both the current and voltage output.

For a deeper dive into battery technology and related insights, explore my Quora profile. Understanding the nuances of mAh vs. Wh can help you make informed decisions when choosing and using power banks for your devices.