Dangerous Goods Practice Test 2026 - Free Dangerous Goods Exam Practice Questions and Study Guide

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What is the watt-hour rating of a power bank rated 20000mAh at 3.7V?

50Wh

60Wh

74Wh

To determine the watt-hour (Wh) rating of a power bank rated at 20000mAh (milliamp hours) and 3.7V (volts), it's essential to use the relationship between these units. The watt-hour rating can be calculated using the formula:

\[ \text{Wh} = \text{mAh} \times \text{V} \div 1000 \]

First, convert the mAh rating to Ah (amp hours) by dividing by 1000:

\[ 20000mAh = 20Ah \]

Now, we can substitute the values into the formula:

\[ \text{Wh} = 20Ah \times 3.7V \]

Calculating this gives:

\[ \text{Wh} = 20 \times 3.7 = 74Wh \]

Therefore, the watt-hour rating of the power bank, which is 74Wh, is crucial for understanding how much energy the power bank can store and deliver. This rating helps in assessing compatibility with devices it intends to charge, ensuring that users are aware of its capacity in terms of energy. The calculation reflects the power bank's total energy available for use, making it an essential piece of information

80Wh