How to Test If Your Micro-USB Cable Is Charging Properly

Skye Hudson 17-03-2015

Different chargers are going to charge your Android device at different rates, and some broken chargers might not be charging your device as quickly as they claim they can.


If you’ve ever run into issues charging your device, or you’d just like to test out how effective your charger is, read on. Today, we’re going to step through how to measure the amperage your charger is delivering to your smartphone or tablet.

Download Ampere


The first step is to grab this handy app from the Play Store called Ampere, which will do the measuring for you. It should work on any device running Android 4.0 and above, though the developer has noted in the description that certain models aren’t behaving quite right, like the HTC One M7 and M8.

Once you have that downloaded, open it up, and you can get to testing.

Testing Your Charger

For this, all you’re going to need is your charger and a place to plug it in — either a safe charging device 7 Ways to Check Your Smartphone Charger Is Safe to Use Defective smartphone chargers cause fires. So how can you check if the charger that recharges your phone or tablet is safe? Read More and wall outlet, a computer (like the brand new Dell XPS 13 Dell XPS 13 2015 Review and Giveaway The XPS represents the pinnacle of laptop design in 2015, and it's the best bang for your buck out of any laptop we've ever seen in the $800 price range. Read More ), or a portable battery (like the amazing Lumsing Powerbank Lumsing Powerbank 10,400 mAh Portable Battery Pack Review and Giveaway So many devices, so little power. The Lumsing 10,400mAh battery pack is a portable backup for when times are demanding. Read More ).


For the most accurate measurement of your charger’s full capabilities, plug it into its official USB to wall outlet adapter, and plug that into your nearest outlet. We’ll discuss in the next section how plugging into your computer can change your results.


Above, you can see some of the information provided by the app. It takes about 10 seconds to measure the charge of your phone, which is what you see on the left. On the right is the settings menu, which you will probably never have to visit.

There is an option to buy the Pro version to remove the adverts that display along the bottom, but they’re so unobtrusive that it’s barely worth the $1.13 to get rid of them. The other reason you may want to get the Pro version would be for the persistent notification that displays battery info in your notification tray.


The app will use orange text when you’re not plugged in and blue text when you are plugged in. When not plugged in, you can see how much energy your phone is currently using. This number will vary depending on how many things your phone is trying to do at once.

Below, you can see my phone with the brightness set to low (left) and the brightness set to high (right). Clearly, the brightness of my screen is quite a major pull on my battery, but other factors can influence this too, including apps updating in the background, Wi-Fi or cellular signal strength, and more.


The app itself uses a very modern Lollipop-based Exploring Android L: What Exactly Is Material Design? You may have heard about Android L and Material Design, but what exactly is this new design philosophy and how will it affect Android and other Google products? Read More  design, which is easy on the eyes. Tapping the circular icon to the left will take you to your full battery stats. Negative numbers mean that your phone is losing charge, and positive numbers show how much charge it is gaining.


Keep in mind that if your phone is working extra hard and using more amperage than usual, then you might get a lower number when testing your charger, and that’s not your charger’s fault.

For instance, if your phone is sucking up -240mA as mine was doing above, and your charger is supplying you with 600mA, then you’re really only going to be charging with 360mA.

What Should You Expect?

Every charging cable is different, but your best bet for measuring your wall charger is looking at the label on the adapter. Somewhere on your USB to wall outlet adapter there will be either a sticker or an imprint in tiny font that details your adapter’s specifications. Below, you can see the charger I was using for this.



You’re looking for the area where it says Output. In this case, the output is 1,000mA. So I should expect about a 1,000mA charge, minus whatever my phone is sucking up (240mA-510mA depending on my brightness).

Your charger and phone will be different than mine, though. But don’t worry, if you’ve used the app and determined that you’re getting less of a charge than your adapter says you should be getting, there are some steps you can take.

Make Adjustments

If you’re not getting a charge as fast as you want, there are ways to increase your charging speed 4 Tips To Increase Smartphone Charging Speeds Faced with a low battery warning right before you need to leave? These neat tricks can help you charge your smartphone faster than usual so you aren't left with a brick in your hand. Read More .

For instance, switching your phone into airplane mode and keeping the screen off while it’s charging will allow it to charge much faster. If you’re not willing to go that far though, we have some other tips for squeezing the most battery life out of your device 10 Proven and Tested Tips to Extend Battery Life on Android Suffering from poor battery life on Android? Follow these tips to get more juice out of your Android device's battery. Read More .

Also, plugging your phone into a computer or a wall outlet may seem like they do the same thing, but they’re much different. Computers can’t output the same level of amperage as a wall socket can. Below, you can see my charger speeds when plugged into the wall (left) and when plugged into my computer (right).


It’s also recommended that you use the charging cable that your phone or tablet shipped with, rather than a third-party charger. The hardware manufacturer has tested your device with that cable specifically, and you know it has the right amperage.

If your phone supports wireless charging What Is Wireless Charging & How Exactly Does It Work? [MakeUseOf Explains] We live in a wireless world. Except we don’t. Sure, we can send huge amounts of information across the airwaves, but the devices capable of sending and receiving it are tied down to power cords.... Read More , that’s going to be even slower than charging from your computer. It’s convenient for sure, but still quite slow.

And, for complete optimum charging, keep it cool. Heat is bad news for batteries, and one of the big things you should avoid to keep your battery healthy Keep Your Android's Battery Healthy With These Tips Software and apps can only go so far -- what about how to charge and discharge your battery? Learn all the tricks here. Read More . Place it in a cool spot, take it out of its case, and it should charge a bit quicker.

How Did Your Charger Do?

It’s pretty nice that all Android devices use micro-USB charging cables Understand USB Cable Types and Which One to Use Why are there so many different USB cable types? Learn the differences between USB connector types and how to buy the best cable. Read More , even if the charging world is still pretty fragmented Why Can't I Charge All Gadgets With the Same Charger? Not all devices can be charged with the same charger. In fact, not all phones can share a charger either -- even if they're from the same manufacturer. But why? Read More . Though, it can be frustrating that not all micro-USB chargers are created equal.

Image Credits: USB cable Via Shutterstock

Related topics: Android Customization, Battery Life.

Affiliate Disclosure: By buying the products we recommend, you help keep the site alive. Read more.

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  1. Prakash
    June 12, 2018 at 12:37 pm

    I cannot measure mA rate. How can I fix it.

  2. Prakash
    June 12, 2018 at 12:36 pm

    I cannot measure my MA rate can I fix it?

  3. dp
    March 2, 2018 at 3:31 pm

    My question was about testing the cables, not the charger. How do you establish if a cable is defunct?

  4. Edward Champion
    January 15, 2018 at 1:12 am

    What a waste of space! Using a computer to charge a device is irrelevant in a article about getting faster charging. And the word is current, not amperage.

    • pb
      March 16, 2018 at 6:38 am

      Current is Amperage?

  5. Divyanshu
    July 8, 2017 at 4:37 pm

    Mine says 5V 4amp is it good?

  6. Alex Moss
    May 20, 2017 at 5:31 pm

    Anyone know how to install this app on a Kindle Fire HD 8 (6th gen)? I see contrary indications, that it is compatible w/ all Kindle Fires, and that it is not compatible. Any suggestions? Thanks much.

  7. Jerry Roscoe
    April 6, 2017 at 7:25 pm

    This is a great app. I thought the battery on my Nexus 6 was bad but ouch it's expensive - lots of labor to replace. Decided to try AMPERE to see how the charger and cable were doing and found a significant difference in cables and chargers. Brief Summary below after a few tests

    With N6 Charger and Cable 2100ma
    with N6 Charger and cable x 200ma
    with N6 Charger and cable y 1000ma

    Another Charger X N6 cable Port 1 1100ma Port 2 1100 ma
    Charger X Cable x Port 1 200ma Port 2 200 ma
    Charger X Cable y Port 1 1100 ma Port 2 1100 Ma
    BTW Charge X claims to provide 2.4 amps max per each port

    Another Charge Y N6 cable 1100
    Charge y Cable x 200
    Charge Y claims to provide 2.1 amps max

    So cable x is bad and cable y isn't great and my Charger X isn't as good as my N6 Charge with the cable for N6. So much for cheap chargers and cables

    • pedro
      August 11, 2017 at 5:48 pm

      awesome test results, thanks!

  8. Taiga
    February 28, 2017 at 12:39 pm

    Hi, I have nothing useful to add but I applaud you for this fine display of journalism.

    Nice article this time. I've been using Ampere anyway but good job indeed.

  9. Onkar Mohite
    September 13, 2016 at 7:01 pm

    My smartphone is 28 months old , from 2 months back it started charging slow as compared to previous charging . My doubts is my android system started showing notification "USB charge only" whenever it is connected to AC charger. In ampere app shows the same Plugged: USB charger. Can you suggest me how to switch to AC adapter. Ampere range is almost similar in every charging mode i.e. around 430-470ma. may be this is speed of usb charging,I actually dont know the AC adapters charging speed as i started using ampere app when i found this issue. Please help.

  10. Anonymous
    August 20, 2016 at 4:21 pm

    I bought a pair of flat, long USB cables off ebay a while ago to use in a couple of places where the outlet was too far from where I wanted the phone, but I found that even with the screen off and in airplane mode it (Galaxy S5 at the time) would LOSE charge despite showing the charging symbol. I ran ampere it it showed I was getting AT BEST 300mA charge rate despite having a charger capable of putting out 2A! Change to a better cable and suddenly it was up to 1.5-1.8A. I still use one of those flat cables, but ONLY as a data cable. I've bought a good quality, fabric wrapped, 1.5M long cable for charging at work now.

  11. sajal
    July 9, 2016 at 7:01 pm

    I have a charger which can charge at 2.4A (they claim). but what the app shows is that it actually can charge at less than 1A. what might be the cause?

    • Anonymous
      August 20, 2016 at 4:23 pm

      Your phone will only draw what it NEEDS up to either it's maximum capability OR the charger's maximum, whichever is the lowest. Your phone may only be able to charge at 1A, so anything your charger can deliver above than that won't be used. Or it CAN be a low quality cable - try a different one and see if that helps. I've personally seen several cheap cables reduce charge rates.

  12. Cedric Mamo
    July 2, 2016 at 12:27 pm

    just want to point out, since the article seems to fail to mention this, that if your phone is designed to charge at, ex. 2A, you can connect it to a charger capable of supplying 100A and the phone will still charge at 2A

      December 10, 2016 at 9:12 pm

      Mainly because a 100A charger at a few millivolts over your phones voltage (say 5.2v at the wall and a 5V phone) can quite easily turn your battery to smoke (and you) in the event of a surge, brownout or any other power anomaly.

      Volts are tied to Current (Amps) times Resistance. In other words, if you increase the Amperage, you need a lot more resistance to stop Volts flowing into you.

      • Nick
        January 18, 2017 at 1:22 pm

        He was just making a point. Not literally talking about charging a phone with a 100A charger.

        I'll change it so overly literal people can understand.
        "just want to point out, since the article seems to fail to mention this, that if your phone is designed to charge at, ex. 2A, you can connect it to a charger capable of supplying 2.4A and the phone will still charge at 2A"

  13. Mikael Thelin
    April 15, 2016 at 7:13 pm

    This app does not work accurately on the Galaxy Note 3.
    Using generic charger A (2A) and Belkin Cable A it says 1200ma
    After 10 minutes battery power dropped 1%
    Using generic charger A (2A) and generic Cable B it says 600 ma.
    After 7 minutes battery power increased 1%.
    Using Zeskit charger B (2.4A) and Belkin Cable A it says 1200 ma.
    After 6 minutes battery power increased 2%
    At least for my phone, the best test is to watch the charge over a specific period of time and test with alternate cables (if optional)

      December 10, 2016 at 9:15 pm

      Reset your battery stats before you start using the percentage there to calculate anything. Ampere and your internal battery stats come from different metrics, but ultimately Ampere is based on real internal electrical measurements and your Percentage bar is the roughest of rough approximations based on how your battery should have worked the day you got it.

  14. Rolfhu
    January 22, 2016 at 6:49 pm

    Just installed it on my LG Flex.Not very clear what I do with this app. It shows quick charging but the value remains at -200 mA. Menus on top almost not visible. 3.Menu is only Advertisement ?

  15. Anonymous
    June 12, 2015 at 8:38 am

    I wish I could try this app, but it says it's not compatible. I have a Samsung Galaxy S3, and I turn off location and other services when I don't need them, but I still can't get through the day without charging my phone at least once. I'm not always near a charger, so I'm pretty much out of luck then. I have different chargers around my house, including a 2 amp one I bought that says it specifically works with Samsung phones, and I was hoping to be able to use this app to test them out. Are there any other apps available that do something similar that work with the Galaxy S3, or am I out of luck?

  16. Mike Sanchez
    April 6, 2015 at 1:08 pm

    Hi people.
    I've got a galaxy s5 (G900F)

    i tried this app.

    when the screen is on , the charging would be 1200mA but if I turn the screen off and let it and then measure the power , it would be 1800 (interesting I guess)

    but in my HP4540s laptop it would be 450mA.

    Really good app.

    you can use this one too , which doesn't take 10 seconds to measure

    "galaxy charging current"

    Thanks dear Justin for our nice posts

  17. John Gaudino
    March 31, 2015 at 3:07 am

    great little utility what I would like to see and hear more about from other users is the difficulty not with the cable but with the micro USB port itself. every single phone I have owned with micro USB eventually the port becomes deformed to loose and charging becomes impossible without contorting the cable to somehow apply pressure to get contact I have returned a dozen phones because of this it happens after about 6 months of use and its frustrating as hell. I ask friends who have apples they say they experience some of the same problem with the Lightning connector is there any hope on the horizon?

  18. Rolfhu
    March 26, 2015 at 9:28 am

    Get on my LG Flex only 200 mA charging, whatever I do.

    • Asterios
      January 4, 2016 at 11:32 am

      hi i have developed an app "charger tester" is the name and works with lg devices. Give it a try.

      • Murray Poole
        July 2, 2016 at 1:43 pm

        That's what I had to do. Thanks.

  19. Mrklaw
    March 21, 2015 at 12:47 pm

    Does the app log charging information? Would be good to be able to record charging speed while the screen is off and then check on the results shortly afterwards

  20. John Williams
    March 19, 2015 at 5:47 pm

    Pay the man his dollar and change FFS! Not only will you discover what charges your phone fastest, but you'll learn all the ways to turn unnecessary stuff off to make your battery last all day. It's all there in blue and orange. An app as useful as this should be paid for.
    Charger identification was introduced by Apple to make sure you only bought real Apple chargers. Android developed it to change the charge rate depending on whether the phone was connected to a mains power adapter, or a USB port.
    Charge rate switching is acheived by resistor networks across the big USB plug. Some 3rd party chargers say than can deliver 2 Amps, but using the wrong cable can throttle it down to 800mA.
    The only way to know and to allow you to use non OEM cheaper chargers and cables is to buy the Ampere App. The Dollar 13 will save you many more Dollars in over-expensive OEM chargers.
    All chargers are made in China. Some of them will burn your house down. Don't buy the cheapest no-name charger .... or you may die!!

  21. Ann
    March 19, 2015 at 5:41 pm

    Good piece, Justin! Would you (or anyone reading comments) know if charging a nokia lumia 635 phone with a charger cable for an Optimus G Pro (E980) damage the phone? It seems to fit and charge the phone, but wondering there will be trouble down the line.

    Thank you!

  22. Randy
    March 19, 2015 at 2:34 pm

    Great article! I will try this app.

    You state in the last paragraph that to use the supplied cables as it will have the correct amperage. Batteries have amperage, not cables. You meant that the supplied cable is rated to carry the full amperage supplied by the charger. Most cables have no problems with the higher amperage, if not they will get warm or hot and are obvious there is a problem. The bigger problem is that a third party cable might not even be wired to supply power and will transfer data but not recharge at all.

  23. Henrik
    March 18, 2015 at 11:52 pm

    Actually this article is not completely adequate, at least two other factors are important:

    Without going too much into detail, the way the USB charger cable is constructed is critical, most of the usb cables will be detected as data lines by your phone, and it will limit the charging power to 500 milliamps, which is not enough if you run for instance GPS software. In this case it does not matter if your charger is able to output 2 amps, it will only charge with the 500 ma.
    To overcome this you will need a "dumb" cable, which you can get at this company: they also have a special "USB tip", which will convert your old USB cable into a "fastcharge" cable.

    And if you own a modern smartphone chances are it will have a Qualcom chip in it that supports "Qualcom Quickcharge 2.0" charging, which is very likely to be activated in your phones OS (search the internet to find out), it is in my Lumia 930 for instance, and then it will be able to charge with 20 Watts.

    Portapow also has very handy hardware inline current and voltage testers, but if they are a bit too expensive for this task, you can have extremely cheap (less than 5$) inline testers for this purpose from China (aliexpress is just one of the possible sources)

  24. 5lita5
    March 18, 2015 at 11:25 pm

    Is there anything like this available for Apple products?

  25. Bob Brandt
    March 18, 2015 at 9:35 pm

    When discharging it read 0 mA. When plugged in whether a 2a or 1a charger it reads it is charging at 1150mA. It reads the same when plugged into my laptop. Something is wrong.

  26. Leah
    March 18, 2015 at 6:20 pm

    Keeps reading zero. Is this because I have a bad charger? It charges, it does.

  27. Kenith
    March 18, 2015 at 4:44 pm

    Is there anything like this available for Apple products?

  28. Nickle
    March 18, 2015 at 8:11 am

    Now, What about cables? Im a truck driver so if something goes bad, kinda have to live with it for a bit. Anyways, my codriver has told me that my micro usb cord doesn't work with his phone, even plugged into the original adapter that came with his phone... Is it possible for companies to priortize (?) (make propritery) cables for phones even if it still falls into the micro usb category?

  29. Foundaspace
    March 18, 2015 at 7:54 am

    Great share!
    Thanks for sharing this.
    This does help me a lot. :)

  30. Richard Allen
    March 18, 2015 at 7:10 am

    I've been meaning to check the charging rate using different chargers and cables for a very long time. Never got around to it because I knew I was getting good charging rates. Just for comparison purposes I'm posting my results. :-p
    Nexus 5, stock 4.4.4, Elementalx custom kernel with usb fastcharge enabled. Using Asus cable and charger (5.2v/1.35A) supplied with Nexus 7 (2013)
    Discharge = 120-150 mA nighttime very low brightness
    USB = 530-580 mA
    Wall = 1020-1030 mA
    Qi = 650-690 mA Koolpad T-100 wireless charger plugged into Asus charger.

    Nexus 7, stock 4.4.4, ElementalX kernel w/usb fastcharge. "Ampere" does not show discharge rate. ;(
    USB = 640-660 mA
    Wall = 1020-1040 mA
    Qi = 450-580 mA Koolpad T-100 plugged into Asus charger.

    Thanks for the article, I've been meaning to check this for some time now!

  31. Earl
    March 18, 2015 at 3:35 am

    I am using a Lenovo IdeaTabS6000-F and although it is charging and Ampere is reading and working - it is strangley coming up with 0mA ??
    Hmmm... I am going to have to look into this a bit more.
    Great article Justin, and timley too as I was thinking about this yesterday and had forgotten you had just written this until today.

  32. murlidhar
    March 18, 2015 at 3:23 am

    please don't say it is barely worth $1.13. the developer has made good application that nobody could think of till now. he didn't even make it a compulsion to buy it. personally i think it is worth paying that money. it costs just a meal in some fast food chain restaurant (in India at McDonald , not sure about anywhere else) i don't know the developer personally or professionally but i do really commend his/her idea the most and then for implementing it. a smart phone can't be smart enough without such developers and without such ideas.

    • Peter from Brisbin
      March 18, 2015 at 10:55 pm

      I agree, this person put some time into the app. For the SMALL sum of $1.13, a bit more in Australia since we lost US parity, it is a good way of saying thank you. It also encourages the developer to write more good apps. I will now try it on my Blackberry Z10 and see if it works there too.

    • Andrew
      March 22, 2015 at 5:10 pm

      Cost almost as much as a big pack of Wrigley gum but sure less than a small coffee.

    • DD
      June 11, 2016 at 3:19 am

      Won't get a cent from me.

  33. Fik of borg
    March 18, 2015 at 1:55 am

    Read zero no matter what. Old phone, I guess (Samsung i9100)

  34. Savio
    March 17, 2015 at 7:50 pm

    It would probably be interesting for me to mention how I charge my z3 compact.
    These are the values from Ampere keeping all factors constant (my socket charger is rated at 1500mA output)-
    Discharging: ~350mA
    Charging: ~770mA (with 3rd party Magnetic charging port cable-with LED charging indicator)
    Charging: it went up to 1020mA (with provided SONY micro usb cable)

    • Justin Dennis
      March 18, 2015 at 1:34 am

      interesting! thanks for sharing. :)

  35. dekka
    March 17, 2015 at 6:58 pm

    this works well with my Samsung s5 .I am very impressed with the info its gives me . can definatley recommend this App

    • Justin Dennis
      March 18, 2015 at 1:35 am

      glad you like it! thanks for letting us know. :D

  36. David Kinlay
    March 17, 2015 at 5:05 pm

    Just wondering if there is any alternative for the htc one m8 smartphone?

    • Justin Dennis
      March 18, 2015 at 1:33 am

      sorry, haven't found anything for it yet. :/