How Many Times Can a Phone Be Charged from a Power Bank?
Mobile devices have become an essential part of our daily lives, but what if your device runs out of battery and there’s no outlet nearby? A power bank helps extend your phone’s battery life, but how do you determine how many times you can charge your phone from it? In this article, we will explore the key factors that affect the number of charges.
What Is the Actual Capacity of a Power Bank?
Stated vs. Actual Capacity
Manufacturers typically indicate only the internal battery capacity of a power bank in milliamp-hours (mAh) based on its own voltage, usually 3.7V. This can mislead users who assume that a 30,000 mAh power bank can charge a smartphone with a 5,000 mAh battery six times. In reality, this is not the case.
Real Capacity of a Power Bank
A high-quality 30,000 mAh power bank actually delivers between 17,500–20,500 mAh, depending on its efficiency (conversion rate). Smartphones and tablets charge at 5V. To calculate the actual output capacity, we need to convert 3.7V to 5V and consider the power bank’s efficiency (typically around 85%), which depends on the quality of its electronic components.
For a 30,000 mAh power bank, the effective capacity would be:
30,000 mAh × 3.7V / 5V × 85% ≈ 18,870 mAh
How Much Energy Is Needed to Charge a Phone?
Energy Loss During Charging
Charging a device requires 29%–43% more energy than its battery capacity. For most devices, the loss is about 37%–38%. Apple devices have a more advanced charging system, resulting in only about a 29% energy loss. On average, the efficiency of all electronics involved in charging a smartphone or tablet from a power bank is around 65%.
For a smartphone with a 5,000 mAh battery, the energy required for a full charge is approximately:
5,000 mAh × 1.35 ≈ 6,750 mAh
Calculating the Number of Charges
Considering all the factors mentioned above, we can determine how many times a 30,000 mAh power bank can charge a smartphone with a 5,000 mAh battery:
18,870 mAh (effective power bank capacity) / 6,750 mAh (energy needed for a full charge) ≈ 2.5 times
The number of charges a phone gets from a power bank depends on several factors: the stated capacity of the power bank, its effective capacity, energy loss during charging, and the efficiency of the charging controller. Simple calculations can help you understand how many times you can charge your phone and how to use your power bank optimally.
You can always use our calculator to estimate the number of charges. Keep in mind that the results are for reference only.
Now that you know how to calculate the number of charges, you can plan your device usage more efficiently and always stay connected.