Quick Guide: How Do Power Banks Work?

Quick Guide: How Do Power Banks Work?

Found in the pockets of millions around the world, power banks are a must-have accessory for phones, tablets, and other smart devices. Despite their popularity, not everyone is clear about how power banks work or are familiar with the technology inside them. So if you cannot tell input from output or USB Type-C from Type-A, read on for our no-nonsense guide to understanding the technology found in your portable charger.

Battery Size

If you are still unsure what a portable charger is, it’s a compact device that houses a battery that can be used to charge a digital device like a phone, tablet, digital camera, laptop, mp3 player, or any other USB-powered product. Portable chargers are not all the same and one of the things that distinguishes them is the battery size. Naturally the larger the battery, the more times your smart device can recharge. For example, a pocket friendly portable charger with a 3350mAh battery might only charge an iPhone 7 once. On the other hand, a far larger device with a 27000mAh battery can charge the same iPhone 8 times.


A device that charges with 1 amp can be used with a 1A output charger and will charge at a normal speed and within a standard time. However, if charging an iPad, a portable charger with a 1A output will take double the time. This is because an iPad requires 2 amps to charge, which means a 2A charger or above is needed. When there are multiple outputs on a power bank, it is common to find 2.4A, 2.1A, and 1A outputs together. With simultaneous charging across all three of those ports, all devices, no matter their charging amplitude, can power up.

RAVPower Input Output Chargers


Input on the other hand refers to charging the power bank itself. Similar to speed limitations on output charging, the input charging speed is dependent on the type of wall charger used. A standard wall charger that provides a 2A output would recharge the power bank twice as fast as one with only 1A. However, this requires that the portable charger support a 2A input. The vast majority of power banks currently do not support that. That said, with technology advances, the recharge speed of most power banks has increased. While 1A has long been the standard input, 2A is becoming more and more common.

Quick Charge

Qualcomm’s rapid charging technology has proven to be the current fastest recharge speed on the market. Now in the third generation of their Quick Charge series, devices with a Qualcomm Snapdragon processor require only 5 minutes of charging to get back 5 hours of battery life. It is so fast that it can get 66% of your phone battery back in only 27 minutes. Power banks with Qualcomm Quick Charge technology are not limited to faster output rates. The technology allows for a faster input meaning you can get a rapid recharge that is even quicker than the already fast 2A input.

Want to learn more about our Quick Charge technology? Clear here.

iSmart Charging

iSmart Technology is a RAVPower exclusive and is a form of integrated automatic charging. The way it works is that iSmart will analyze and determine the optimized charging current for any connected device. If a device requires a 1.8A charge, iSmart will change the current flow to get that device’s ideal charge. The recently upgraded iSmart 2.0 technology also corrects irregular charging behavior, offers 10 improved safeguards and protections, and balances the current output when charging multiple devices at once. For those that want the best charge for their device, the tailored charging of iSmart is something you will always need from your next portable charger.

Want to learn more about our iSmart technology? Clear here.

USB Type-C

The latest in USB technology is USB Type-C / USB-C. Relatively new, the reversible head and smaller size stand in contrast from the older yet familiar USB Type-A. Type-A, of course, being the standard USB input nearly all charging cables use. While power banks have traditionally catered for USB Type-A inputs, the latest power banks support USB-C as it slowly becomes the newest standard for transferring and charging. When recharging with USB Type-C, a 20100mAh power bank will take just 4 hours to be recharge. Conversely, charging with a standard 1A charger can take close to 30 hours. What is even better is that USB Type-C compatible portable chargers can power the latest MacBook as fast as the original 30W charger so you can have mobile charging on the go wherever you are. In addition, if you are charging your Nintendo Switch then you will need a USB-C charger and cable.

Please note: An appropriate USB Type-C charger and USB-Type C cable are necessary to achieve these speeds.


Carrying a little device with serious power might raise a few safety concerns. Even airlines limit flying with portable chargers that exceed battery limits. Thankfully, any external battery charger worth purchasing comes with a bare minimum of safety protections to safeguard your devices. These protections help to prevent malfunctions or more serious safety risks. Mandatory protections include over-charge and short-circuiting, with extra protections needed depending on the battery size. These extras include over-discharge, surge current, surge voltage, over-current, high temperature, a safe reset mechanism, reverse connection, and EMF protections. An exhaustive list? Yes, but all have their useful purposes, especially if you do not handle or charge your external battery correctly.

RAVPower Protections Power Bank Infographic Power Banks


Not found in every portable charger, these extras can enhance the user experience making for greater convenience or improved safety:
Built-In AC Pins: For those travelling, power banks with built-in AC pins require you to connect to a socket to recharge; saving you from bringing a cable and a wall charger.
Waterproof or Shockproof Protections: In addition to internal protections, power banks also contain durable outer protections in the form of one-cast casing, or thicker, rugged hard shells. It is very useful as a safety precaution, especially if used daily.
AC Output Less common but still a feature found in incredibly powerful chargers, a built-in AC output can power 110V home appliances so you can be mobile with your favorite gadgets.

Portable chargers are not hard to understand – simply connect your phone, tablet, or other device and charge. However, they contain technology that might not be clear to everyone. We hope now that you can tell the key differences between input and output, or iSmart Charging or Quick Charge technology. Happy charging.

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53 Replies to “Quick Guide: How Do Power Banks Work?

  1. Have a question: Can I find a power cord that has a usb on both ends to power up the battery in a car charger or can only charge it in a a/c outlet?
    Like this charger I purchased from you all. Just wish there was a way to charge the power Bank in the car…example vacation…long trips etc…

    1. Hi Helen,
      We don’t currently sell a dual USB cord but we do have a USB car charger. It connects via your cigarette lighter socket and can charge two devices simultaneously. It might not be exactly what you are after but you can use it to charge your device when driving instead of only using a power bank. You can find it here.
      Hope that helps.

  2. Can I charge a small Ravpower from a larger one? My idea is to keep a large one at camp and use the smaller one while hiking etc… away from base camp so as not to have the extra weight.

    1. Hi Jerry,
      We do not recommend that. There will be a loss of power due to the output conversion rate when using a larger charger to power a smaller one. We hope to cover this soon in a blog post.

  3. We just purchased a 16750 mAh deluxe series external battery pack , the instructions don’t tell you when the battery pack is fully charged ..How do you know ??

  4. Having a powerbank available can be a lifesaver, however, you still need to remember to charge it. Do you have and solar powered charger available in your product line?

  5. I use my Xtreme RP-PB14 to power my electric spinning wheel that needs 12V. I must have misplaced my paperwork. I charged up the power pack and when it was at 100% power, it says it is at 9V. I don’t want to plug it into my spinning wheel until I can make sure it is at 12V DC output. Can you give me a quick resource to check on the technique to change the output to 12V? Thanks.

    1. Hi Linda,
      Please press and hold the power button to see the 9V icon flashing on the LCD screen. If you press the power button again you can change cycle through the voltages to 12V. I hope this helps!

  6. If completely flat does power bank light come on when charging straight away or can it take time not sure if not working it’s RP-PB19

  7. I bought RAVPower 20100 MAH which has USB Type C for Input and Output charging. My question, is it okay to charge mobile phone Samsung S7 from the USB Type C (using USB Type C to Micro USB adapter) ? Thanks in advance.

  8. Hi there – I recently purchased a RAVPower RP-PB043 20,100mAh Battery Pack. Am I okay to charge it with the wall wart/mains charger I had included with my Samsung S8 mobile phone? Or even this particular USB C wall wart/mains charger: https://www.amazon.co.uk/gp/product/B073Z851J1/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

    If both are fine, would there be a difference in the charge speed? Just want to make sure I don’t damage my charger (I’m currently using my laptop to charge it!) but also want to make sure I get an idea if it’ll be 30 hours or 4 😉

    Thank you!

    1. Hi Corey,
      The S8 adapter is compatible with the RP-PB043 as it can support 5V/2A charging.
      And you are welcome to try an Aukey charger, however, we really think these two chargers are better (and more affordable):
      Quick Charge 3.0 Charger
      USB-C Charger
      Please note that the QC charger will be best as it will charge your power bank even quicker than the Type-C charger.
      Hope this helps you.

  9. Hi Can i connect two iSmart (Type B) ports output in parallel to drive a larger load ?
    Port 1 rating 5V/2A max & Port 2 5V/2A max, so when i connect both port 1 & 2 in parallel, can i drive a load of 5V/4A max. Please clarity

    1. Hi Kumar,
      If you connect two ports at the same time, only one port will put out the max power, not both ports. Basically power adjusts to each device’s needs with more power being delivered to the device requiring the more powerful charge. Hope that helps.

  10. Hi There,

    Have bought a ravpower super c series 26800mAh and am having trouble reversing the power delivery to charge devices. Forums seem to say to hold power button for 5 seconds but this doesn’t work. Could someone please advise.

    Many thanks

  11. Do you have a power bank that’s rugged and drop proof? I’m disabled and only have use of one hand, I drop things a lot and unfortunately the outcome isn’t so good.

  12. Hi,

    I have the same problem with my power bank than Alan Taroud (20100 mah with power delivery).

    I’ve bought it and tried to recharge it with my huawei usb-c cable and charger but the leds are still off.
    I can charge it with a usb cable.
    The usb-c output is correct with my huawei mate 20.

    I’ve contacted the support and a second power bank has been sent but the problem is still the same.

    I’ve already tryed others chargers and others usb-c cables and the usb-c input doesn’t work.

    Can you contact me in order to solve this problem ?

    1. Hi Philippe

      We can’t contact you directly, but the USB-C should be available for input as well as output.

      Please get back in contact with Support. They should be able to help you get to the bottom of this issue!

      For now, we suggest charging it with the cable that you mention works for you.

  13. Your article is really helpful. Because After reading this article anybody ( like me) who wants to purchase a power bank can easily make a decision which brands power bank he should purchase. Thanks for sharing… Keep Sharing

  14. Very useful information about power banks is given in this article. I learned a lot from your blog. Thanks a lot for sharing this article.

  15. Hi, blog team
    The blog is really useful, but I have 3 questions:

    1- I just bought a Ravpower. The instructions say “Don’t exceed the power output rating for each port.” How can I know if I’m exceeding it or not?

    2- Can I use power bank to charge my laptop?

    3- Can I use the power bank to charge my laptop at the same time with my two mobiles?

    Thank you in advance!

  16. Nowadays no one has an interest in knowing the mechanism of things which they are using. I was looking for how power banks work and I came to the right place because I got to know all information with an image to understand more easily. Keep posting.

  17. This article has described whole process of power bank working, how it works, and use. I got to know that there are cells in power banks that charge and contain charging. Keep posting.

  18. We also use power banks with our wireless water pump controllers and this info helped greatly ,some home automation units always need portable power and power banks are one handy thing when it comes to that , also our automatic water pump controllers in remote area also can benefit with this all

  19. Hi good day.
    I’ve purchased the ravpower 20100mah blade series.
    The issue is that the usb type-c for reason doesn’t charge my mobile or my nintendo switch. I haven’t tried it with anything else. The cable it came with works fine if I use it to connect my mobile to my pc, so no issue with the cable. However trying to charge from the powerbank to my device then it doesn’t pick up any current.
    The usb type-c port does work when charging the powerbank connect to the wall socket so input works but doesn’t want to output current.
    Any ideas?
    Am I doing something wrong? Is there a code button that I must press?
    Please help.


  20. Is there a beginner how-to-use file I might read?
    The cord provided plugs into wall transformer; 4 blue lights appear. How do I know it is charged?

    1. Hi, our support team will be happy to help if you send them an email (support@ravpower.com) and let them know which model you would like to know more about.

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