WM5 will give you at least 25% of battery life.

WM5 will give you at least 25% more battery life.

According to Mike Calligaro, member of Microsoft Mobile Team, the fact that Windows Mobile 5 use Persistent Storage to keep the data safe in your Pocket PC will give you from 25% to 50% more of battery live.

“when we shut you down because your batteries were "critically low," they were still 1/4 to 1/2 full.  Why?  Because, if the batteries ever fully died, it would be catastrophic.  You'd lose your data, and that's, in our opinion, one of the worst things that can happen.  So we made a requirement and held our OEMs to it.  The requirement was that, at the point where we decided the batteries were "critically low," they had to still have enough power to keep the RAM charged for 72 hours.  The idea there was that you could discover that you were out of power on Friday on the way home and you'd still have your data on Monday when you got back to your charger.” – Mike Calligaro says.

“A typical battery holds 1000mAh of charge.  128M of RAM takes about 500mAh to stay resident for 72 hours.  64M takes about 250.  This is why you never saw a 256M WM 2003 device.  It would have run for a minute then decided its batteries were critically low.” – He added.

So taking in consideration the above explained, we could see from 25% to 50% more of battery life depending of your current amount of RAM.