Significantly improved battery life in Windows Mobile 5.0 explained

I think Josh Bancroft, from TinyScreenfuls.com, does an excellent job with his podcasts and I really enjoyed listening to the latest show. As you may have read in my X51v review or in Chris’ X51v review we both saw double the battery life in the X51v over the X50v in Spb Benchmark testing. I knew that using Windows Mobile 5.0 with the new memory management configuration had a big impact on battery life since ROM requires less power than RAM, etc., but after listening to Josh’s podcast I now understand a bit more and believe that our double battery life benchmarks are correct. You see in the WM 2003 SE and earlier OS versions RAM had to be powered up to maintain the programs and files you loaded into RAM and this consumed power. As I understand it (check out the details in this Windows Mobile team blog post), Microsoft required that a device could be turned off for at least 72 hours straight without losing data and since data was in RAM there had to be some power being fed to RAM. As a result, manufacturers dedicated something like 30-50% of the battery capacity to this requirement and if you ran low on your battery you would see warnings pop up. There was still quite a bit of your battery capacity remaining, but this was locked down by manufacturers.

Now in WM 5.0, RAM is only used to run applications and no data or programs are stored there. You will see on the Power utility that there is no longer any status for a backup battery because it is no longer needed. You can take out your battery for as long as you want and all your data and applications wil still be on the device when you power it back up. Manufacturers can now use the full battery capacity and thus we are seeing huge increases in battery life of Windows Mobile 5 devices.

If you are an X50v owner, I highly recommend you order the WM 5.0 upgrade CD when it becomes available, supposed to be this week.

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  1. #1 by Josh Bancroft on September 28, 2005 - 14:58

    Glad you found my explanation useful. I kind of rambled on and on about it in the podcast, but I wanted to explain it thoroughly. 🙂

    Love the blog – I’m subscribed! We should have lunch or something next time I’m in the Seattle area (or if you ever come to Portland). 🙂

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