The scenario I would want to have this is if I want to quickly drain the battery so I can charge it fully again. Some say that this will help extend the battery life by fully draining/charging the battery.

How to drain the battery quickly?

  • This will only have adverse effects on the battery life. It may be needed for gauges of certain batteries but not recommended as it decreases battery life.
    – Sophile
    Mar 27, 2023 at 8:34

10 Answers 10


This question is along these same lines: What causes battery to drain faster than it can charge?

So there may or may not be an app designed to drain the battery but you probably just need to turn on an app that uses the GPS. This will help to fully drain your battery but I don't know that doing so before recharging will extend the battery life.


Enable your GPS and use navigator to some location you are not going to that is far away. Then watch a movie on your phone with brightness on max.

This will get the job done.

  • 2
    I wound up watching youtube, streaming pandora, leaving the flashlight on full power, and playing angry birds.
    – knpwrs
    Nov 15, 2010 at 3:09
  • @npsken: does not youtube automatically stop when you minimize?
    – Louis Rhys
    Nov 19, 2010 at 10:15
  • I believe it does. I just kept it open.
    – knpwrs
    Nov 19, 2010 at 10:59

Do not do this. You are actually harming the lifespan of your battery when fully discharging it before a recharge. See this site for a discussion of how depth of discharge affects battery life.

The only reason you might want to fully discharge before a recharge is if you have a NiCad battery that is susceptible to the memory effect. Your smartphone most likely uses a Lithium-ion polymer battery, so there is no good reason for you to totally discharge your battery. The lifetime is longer if you have a shallow depth of discharge.

  • 1
    Below is cited from this question "Batteries with fuel gauge (laptops) should be calibrated by applying a deliberate full discharge once every 30 charges. Running the pack down in the equipment does this. If ignored, the fuel gauge will become increasingly less accurate and in some cases cut off the device prematurely."
    – IsmailS
    Apr 28, 2011 at 7:30

Watch a movie with full brightness, download a large file, while enabling WiFi tethering (this is a great battery drain), GPS, Bluetooth, and WiFi at the same time.


I know that my phone -- HTC's Evo -- actually has a diagnostic tool thats sole purpose is to drain the battery as fast as possible. Open up your dialer and enter:


You don't need to press send or anything. A recent update for the Evo blocked these tools so hopefully you can still access them. You can also look up device specific codes if yours happens to be different. Rooted users have found a way to get these tools back.

The utility turns up brightness all the way, prevents sleep, turns on the camera and flash, turns on the GPS and constantly polls it, etc. Basically everything that can drain the battery but not damage the phone is done (ie it doesn't constantly vibrate because that would probably be bad).


If you know some basic programming, you can write an application that just do some random calculations (e.g. calculating primes, factorials, or even folding proteins), request CPU lock, prevent screen from turning off, turn on GPS, Bluetooth, Wifi, turn on vibrators, record videos, etc.


Just play The Elements. A very CPU-intensive game. If you add a lot of stuff to make the simulation very slow, you are sure to use the CPU in full.

Meanwhile, you could use a GPS fix to constantly use your GPS. And you could leave your Bluetooth on. All this at the same time (especially with the Samsung Galaxy S2 & Cyanogenmod) you might end up using more power than your phone can recharge.


I found a combination that draws more than 2 Ampere on my phone without requiring any non-built-in app.

  • Flashlight

  • Brightness to the maximum. Obvious yet easily forgotten.

  • Disable adaptive brightness. Sleep after 30 minutes, or better: play a video.

  • Picture-in-picture video streaming (YouTube, Netflix,...). This keeps active:

    1. The video decoder
    2. The screen
    3. WiFi (or cellular if you can afford it).

    If you can't use the network, try Video Looper, no permissions required. There's also a "loop one" option buried in the options of MX player

  • GPU load like for instance https://jbouny.github.io/fft-ocean/ or https://webglsamples.org/aquarium/aquarium.html keeps the GPU active with just a web browser; no app needed.

  • GPS navigation

  • A fan to avoid thermal throttling

Some apps show the total battery drain.

  • Connect a USB device with a motor, like an external HDD or cooling fan (to the USB port using a USB OTG cable.)
  • Play HD videos at full brightness and sound (from an external HDD)
  • Turn on GPS, WiFi, 3G, Bluetooth, and do searching
  • Unlimited vibrator
  • Run a virus check

Activating WiFi network sharing should empty the battery in a couple of hours.

After the first couple of charge cycles, the battery should be at optimum performance. How this works, I don't really know. But after an initial couple of days, I had a little more use out of a fully charged battery.

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