Nov 28, 2012

Use Wi-Fi instead of 3G to save Android battery life

If you have unlimited data over 3G so that cost is no option, which is more power efficient? Using the WiFi or 3G connection for data usage? Extending battery life being the goal (ignore LTE for now)

As Matthew Read mentions, the hardware, your location, and the other fiddly bits about actual communication are important to the discussion. But, you also need to consider what you're doing with the phone.

Are you retrieving largish amounts of data often? If so, Wifi may be less drain on the battery by letting you finish sooner - remember the screen drains power while you're waiting for 3G to finish what
WiFi may have finished much sooner. (But that depends on what brightness level you have your phone set to.)

Anyway, Google Engineer Jeff Sharkey has shown many interesting indicator


How do these numbers add up in real life?
  • Watching YouTube: 340mA = 3.4 hours
  • Browsing 3G web: 225mA = 5 hours
  • Typical usage: 42mA average = 32 hours
  • EDGE completely idle: 5mA = 9.5 days
  • Airplane mode idle: 2mA = 24 days
From there point, we translate into how much it cost, for example, a bulk data transfer such as a 6MB song:
  • EDGE (90kbps): 300mA * 9.1 min = 45 mAh
  • 3G (300kbps): 210mA * 2.7 min = 9.5 mAh
  • WiFi (1Mbps): 330mA * 48 sec = 4.4 mAh
This calculation does not include screen-on time if you are actively waiting for the downloading process completed. Obviously, using Wifi is more efficient than 3G in term of battery consumption.

Conclusion
Using Wi-Fi data is more battery friendly than 3G.
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