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Android.SE user intuited observes:

I've noticed that my S4 doesn't always charge at its maximum rate of charge, even when it seemingly should. For example, car DC adapters that claim to provide up to 2.0 amp current only provide 500mA.

They also seems to imply that there exists an app which reveals the rate at which a device is charging.

And TurboFool adds:

I used to think "USB is USB," and that's true for data, but not for power. Cable quality, and unknown factors, will change what you can pull off. I've had two [USB] cables of the same length produce as much as an 800mA difference from the same charger.

I own a Samsung Galaxy S Relay, which is an Android phone a few years old. It's sort of similar to the Samsung Galaxy S III, but it also includes a slide-out physical keyboard. I'm running Android 4.1.2.

How can I determine at what rate my phone is charging? Preferably using only an app or a terminal emulator. I'd rather not have to use a multimeter.

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4 Answers 4

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You can try Ampere (I didn't test it), which should show you the current (dis)charge rate:

Ampere Ampere

Quoted from a rating:

I appreciate that this app displays which of my available charging devices delivers the most milliamps. It's useful because I know which charger to swap out for maximum power. Also, it may indicate if a known charger may be under performing based on available specs.

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  • Ampere and similar apps don't work on the Galaxy S Relay. I've tried them. Still, thank you for trying. Commented Aug 26, 2015 at 13:39
  • It's one of the first few apps that I bought from Google Play. Very good.
    – iBug
    Commented Oct 6, 2019 at 7:16
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A terminal emulator? That sounds great!

cat /sys/class/power_supply/battery/current_now
cat /sys/class/power_supply/bms/current_now

You'll get an integer about how many micro-Ampere (μA) your battery is currently outputting/discharging. A negative value means charging.

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I have a couple of apps to suggest:

  • 3C Tool Box. This is a very versatile app and battery-related monitoring is a tiny portion of what it can do. Relevant to your question is that it shows charging current while on charge (Also discharge current/ voltage while in use). Snapshot below of charging on my device

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I would recommend DashClock widget with the BatteryDash extension. BatteryDash is a reasonably simple battery info app with currently drawn amperes, delivery voltage and temperature data. DashClock provides that info through a Home Screen widget and a custom daydream.

Note that DashClock requires Android 4.2+, but BatteryDash doesn't.

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  • Looks like BatteryDash has been taken down from the Play Store. Does this answer still work without BatteryDash?
    – Andrew T.
    Commented May 24 at 9:57
  • @AndrewT. I don't know. I'd probably just use AccuBattery now, but I don't want to necrobump this post. Someone can write a new answer if they want. Commented May 27 at 17:56

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