Understanding Power Bank Specifications: Capacity (mAh), Charging Efficiency, Watt Hours, and More

We live in a digital world and use our devices more than ever before. They help us to navigate, shop online, share our adventures, and do so much more. But sometimes our gadgets can’t keep up with us. They go off when we need them the most. That’s where power banks come in handy.

Power banks are designed to store energy and allow you to recharge devices on the go. They can charge smartphones, tablets, laptops, and other devices—depending on their capacity and efficiency. They connect to rechargeable batteries via USB cables. Today, we’re looking at the power bank specifications that determine performance.

Introduction to the Concept of Power Bank Capacity and mAh (Milliampere-Hours)

Power bank capacity is usually shown in milliampere-hours (mAh) and indicates the charging capabilities. The higher the mAh, the more power the power bank can deliver to your device. Power bank capacity ranges from 3000mAh to well over 30,000mAh.

Dispelling Common Misconceptions About Power Bank Capacities

1.      A Power Bank Can Damage Your Phone

Most power banks use lithium-ion batteries, which are safe for devices. You can even leave your phone plugged in overnight. However, a poorly built power bank can deliver an incorrect voltage and damage your device. Make sure the power bank you get has safety features such as overcharge protection, short-circuiting protection, overheating protection, and more.

2.      Power Banks Take Long to Recharge

While higher-capacity units take longer to charge up, most power banks can fully recharge in hours. To ensure your power bank recharges as fast as possible, use a USB Type-C charger or 2A or above input.

3.     A Power Bank Can Explode

Power banks built with high-quality materials do not explode. Those that explode have low-quality batteries, wrong circuit design, improper insulation, or poor welding. 

4.     Power Banks Cannot Be Taken on Planes

Most airlines allow power banks in carry-on luggage but not in checked baggage. This is because lithium-ion batteries can present a fire hazard. The batteries are generally safe and unlikely to fail, but only if they have no defects. 

How to Calculate the Approximate Number of Device Charges Based on Power Bank Capacity

There’s a common misconception that you simply divide a power bank’s capacity by a device’s capacity to figure out how many times you can use it to charge the device. This is wrong. Capacity (mAh) and energy (Wh) both determine the number of device charges. mAh measures the electric charge, while Wh measures the electric energy.

Watt-Hour = Ampere-Hour x Voltage

Most power banks are created using Li-ion batteries, which have an average voltage of 3.7V. However, when power banks charge other devices, they must supply 5V, the required USB standard. This is why power banks have these values printed on them: 5V/1A, 5V/2A, 5V/2.4A, etc. When 3.7V is converted to 5V, the capacity drops. For example, the actual capacity of a 10000mAh power bank would be:

(3.7V * 10000mAh) / 5V = 7400mAh

In the calculation above, the supplied capacity is actually 26% lower than the advertised capacity. A USB cable used also generates power losses due to its internal resistance.

All these factors determine a power bank’s efficiency rating, which is typically between 80% and 95% (written in decimal). The efficiency rating varies from one battery pack to another.

To determine the actual power capacity, use the following formula: 

Actual capacity = 3.7V x Advertised capacity (10000mAh) x efficiency (0.9) / 5V = 6660mAh.

So, this means a 10000mAh power bank can charge 3000mAh smartphone twice.

Factors That Affect Real-World Charging Efficiency and Actual Power Delivered

  • Capacity: A power bank’s capacity, measured in milliampere-hours (mAh), largely determines its capacity. The higher the capacity, the more charge it can hold.
  • Wattage: A power bank’s wattage determines how quickly it charges devices and itself. For instance, a unit with a 40W output charges twice as fast as a 20W unit.
  • Voltage: Higher voltage power banks provide faster charging. They are more efficient than lower voltage units because they need less current to generate the same amount of power.
  • Charging technology: There are several types of fast charging technologies available on the market—Qualcomm Quick Charge, Power Delivery (PD), and GaN. USB Power Delivery (USB-PD) allows devices to be charged at a faster rate than traditional USB charging.

The Importance of Considering Efficiency Ratings When Choosing a Power Bank

The efficiency rating is expressed as a percentage and ranges from 60% to 95%–. High-efficiency power banks have efficiency ratings of 80% or higher, while standard power banks have ratings between 60% to 75%.

The efficiency rating refers to the conversion efficiency—the difference between the battery’s core energy and rated capacity. For example, if the efficiency rating is 90%, about 10% of the power is lost in the conversion.

Charging Efficiency Technologies Offered by RAVPower

  1. iSmart: This charging technology checks the battery specifications of devices and adjusts the current and charging speed accordingly, helping prolong the battery life. It optimizes the power output for each device.
  2. Qualcomm Quick Charge (QC): Qualcomm’s fast charging standard reduces charging time by many hours. A QC 3.0 charger with a high capacity can fully charge a 3000mAh battery in less than an hour. 15 to 20 minutes of quick charging is enough to keep a smartphone going an entire day.
  3. Power Delivery (PD): Both QC and PD chargers deliver fast charging speeds. However, PD chargers are generally faster because they can deliver more power to charge devices more quickly. USB-PD chargers power devices much faster than traditional chargers.
  4. Gallium Nitride (GaN): GaN charges faster than silicon and can handle higher power levels, which is why it’s used in fast-charging accessories. It is a superior conductor of electricity and can withstand more power without overheating.

4 High-Capacity Power Banks by RAVPower Worth Buying

20000mAh PD Pioneer 60W Power Bank (RP-PB201)

This power bank can pump out up to 60W of juice and charge phones, tablets, and power-hungry laptops with no trouble. It uses PD technology to quickly charge devices and itself. Your MacBook Pro will charge to 50% in less than 30 minutes.

Its 20,000mAh capacity is enough to fully charge a smartphone four times and most USB-C laptops at least once. The USB-A iSmart port is capped at 18W, while the high-powered USB-C port delivers up to 48W when both are used simultaneously.

30000mAh 90W 2-Port Power Bank (AF-PB007)

The 30000mAh Alfox power bank offers 100w charging output and can take a MacBook Pro 14’’ from 0% to 50% in just 36 minutes. It can also charge the latest devices super fast. It only takes 2.5 hours to recharge.

The PD 3.0 port and QC 3.0 port deliver 65W and 18W respectively. The power bank is compatible with almost all USB-powered devices and offers optimal charging speeds. Its advanced safety features protect your devices.

15000mAh 30W USB-C Power Bank (RP-PB203)

This battery pack is small in size but not small in power. Packing 15000mAh, the power bank has a massive 30W total output: an 18W USB-C port and a 12W USB-A port. When connected to a USB-C to lightning cable, the 18W PD port takes only 30 minutes to recharge an iPhone 11 Pro halfway. An 18W PD input allows the unit to fully recharge in 4 hrs. The USB-C power bank offers various charging protections: over-discharge protection, overcurrent protection, short-circuit protection, and overvoltage protection.

10000mAh PD 20W Magsafe Power Bank (RP-PB1212)

This wireless 20W MagSafe power bank offers portable power and is ideal for charging devices on the go. It features a magnetic DC connector that securely attaches to compatible devices, ensuring quick charging. The magnetic connector helps guide it into position for a quick and secure connection. The power bank seamlessly pairs with magnetic phone cases for quick and convenient charging. Say goodbye to unruly wires and enjoy up to 15W fast wireless charging.

Understand Power Bank Capacities to Make Informed Buying Decisions

Now that you understand power bank capacity, take time to find the best charger for your needs. Consider how many devices you’ll need to charge and how often you’ll need to recharge the power bank. The Alfox 30,000mAh 90W Power Bank is ideal if you want a unit that can charge your smartphone, laptop, gaming console, and more.

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