I do not know if people are still interested in this topic, but I thought I would share some of my experience.
The Xperia x10 Mini Pro comes standard with a:
Sony Ericsson Battery [BST-38]
Li-Polymer 3.6V
930mAh
3.3Wh
What causes the VERY POOR battery life is that value in red. That is ALL it is. A smart phone, in this day and age, will NOT RUN as a smartphone with that charge delivery. I dont understand whether this is to reduce production cost but its a good phone if this is resolved.
Now the GOOD thing is this. The battery FOR the Xperia x10 mini pro is a GENERIC Sony Ericsson BST-38 battery. You can also put a Lithium Ion battery in it, instead of Lithium polymer.
My advice would be you upgrade and buy this battery:
CLICK HERE FOR EBAY BST-38 BATTERY
The battery above is from a trusted seller (I have purchased 2).
Stats are as follows:
2500mAH.
Lithum Ion.
This is almost 2.7 times MORE capacity than the STOCK BST-38 you get.
As usual once you get the battery, or any other, standard battery
ettiquitte applies. You must fully charge and fully discharge (light use ONLY) for about 4-5 CYCLES (1 cycle = charge + discharge) before it is cured for proper robust use.
Comparisons:
1 hour for my 930mAh battery to go down to 87% capacity (pre curing).
3 hours 2500mAH battery to go down to 87% capacity (pre curing)
EBL:
930mAh = 6.7hrs (LIGHT use, pre curing)
2500mAh = 21.7 hrs (LIGHT use, pre curing)
This is an OBVIOUS difference. Note these values, of course, will differ however the range (15hrs precured) will remain almost the same in everybody case.
Now of course HEAVY use (im talking about phone ADDICTS, CONSTANT data transmission) will almost destroy half of that 21.7 hrs, but then again that is the INDUSTRY standard for smartphones. And it is a HELL of a lot better than what you get STOCK with the phone.
Of course the best option to MAXIMISE battery life would be to use all those energy saving apps. I am currently using a 2500mAh battery and can tell the difference. I have my brightness on at 50% and the battery life is more than acceptable.
A tip would be also to ALWAYS charge your battery with the WALL charger, not through the PC. only "top up" with the PC-USB charge method.