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I've read mixed reports online about which radio uses more power -- 3G or 4G. Has anyone done any semi-scientific tests that would answer this question?

  • When constantly downloading data over the same period of time, which uses more battery (battery drain per second of download)?
  • When downloading the same amount of data, which uses more battery (battery drain per KB)?
  • Do both radios sleep with the same consistency? Do they use the same amount of power when sleeping or is one better than the other?

I don't think this is a simple question since the different frequencies might take different amounts of power to transmit/receive, since 4G is faster and may get to go back to sleep sooner, since the process of holding onto a signal may be different, etc.

My city won't have 4G until the end of the year but I'd really like to know.

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So I can't give you a scientific (or even semi-scientific) answer, but I can give you an anecdotal one based on my experience over the past couple months..

We have 4G here in Atlanta, and while it works most everywhere I go during the day, I've found myself leaving it off most of the time because it has a noticeable impact on battery drain.

The way I understand it, the 4G radio is separate from the 3G radio, and I'm not sure the 4G radio turns "off" the 3G. I say this because when you use 4G it's possible to receive data during a voice call, which you can't do otherwise.

That said, using the 4G widget it's really easy to flip it on when you need it, and leave it off when you don't. It's not inconvenient, and will help your battery life..

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  • It's been my experience that if you aren't using the 3G radio, it goes to sleep and the battery will last for days. Hopefully with 4G on, the 3G will sleep until it needs to be used (but what exactly would it be used for? Data will go through 4G and there's 1xrtt/2G for voice/SMS/MMS right?) Hopefully the 4G radio has sleep capabilities on par with the 3G, you could maybe confirm this by downloading JuicePlotter.
    – colithium
    Aug 18, 2010 at 7:19
  • That's a good idea.. I just pulled down juice plotter.. I'll let it run a day or so in various modes and let you know what I find out..
    – Don
    Aug 18, 2010 at 14:19
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    Ok, based on 3 days of testing w/Juice Plotter, my battery appears to drain about 30% faster with 4G turned on. Even worse, much of the day I'm inside our office bldg which tends to block the 4G signal. This tells me that the 4G radio doesn't do a good job of sleeping when it can't be used..
    – Don
    Aug 21, 2010 at 2:50
  • Hmm... The 3G radio is also a power suck when it has weak or no signal. However, when it has good signal, it will generally be off most of the time when the screen is off. Does it look like the 4G does this too? 4G doesn't have as good of building penetration as 3G so I don't we're comparing apples to apples here.
    – colithium
    Aug 23, 2010 at 7:24
  • I don't think the 3G radio can turn off, because 4G is only used for data. Voice service has to use 3G.
    – Ben Gartner
    Sep 29, 2010 at 12:01
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Anandtech did some testing with the Evo 4G and found the battery life to be the same when using 4G as when using 3G. http://www.anandtech.com/show/3791/the-sprint-htc-evo-4g-review/12 It is the only semi-scientific testing I've seen.

I find that in Portland, Oregon 4G coverage is spotty so if I leave 4G enabled the battery drains faster. My guess is that it takes more battery power to search for unavailable 4G networks.

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