Hi guys First time Android user with Samsung Galaxy S2 stock KE2 Optus Australia branded phone right now. Have yet to flash to KE7 but getting ~9 1/2hrs normal usage. With Juice Defender free version installed and wifi enabled get around 17-19hrs normal usage or around 9 1/2hrs with 6+ hr session of Angry Birds. Galaxy S2 is on it's 6th charge right now - first 4 charges let it run down to around 44%, 5th charge ran down to 16%. Anyway, I have an Energizer XP8000 - 8000Mah battery back I use for my Acer 3810T Timeline notebook and it has a CB31 tip for Samsung Galaxy S so I assume it works for Galaxy S2 as well. So going to test it out and thought I'd keep my progress updates in this thread for others to read as well. The test subject - brand spanking new Samsung Galaxy S2 Energizer XP8000 Tech Specs: Battery Cell: Lithium Polymer Power Capacity: 8000 mAh Rated Input: DC 12V, Max 3500 mA Rated Output: DC 5V, 1000 mA DC 10.5V, 2000mA DC 19V, 2000mA Recharge Time: ~4 Hrs Weight: 0.5 lbs / 0.22 kg Dimensions: 4.3(L) x 2.9(W) x 0.9(H) inches / 11(L) x 7.3(W) x 2.3(H) cm XP8000 Tips AB03 tip = Acer 3810 Timeline notebook CB31 tip = Samsung Galaxy S/S2 From label you can see it's rated at 30WH. Question: Is it a valid way of testing to connect XP8000 to Galaxy S2 and use phone to see how long it lasts ?? Feel free to chime in and share your own results with external or extended battery packs with Samsung Galaxy S2 -------- Results are in for Samsung Galaxy S2 paired with Energizer XP8000 8000mah external battery pack. The phone has the stock Optus Australia apps and branding still on it. Definitely looks good just pushing total uptime on stock Samsung Galaxy S2 Optus Australia KE2 firmware (unrooted waiting for 2.3.4 at least) to ~52hrs with 6% battery life remaining! Which is 5.47x times more battery life that Stock S2 KE2 and 2.6-4x times more than with Stock S2 KE + Juice Defender. Results Stock S2 KE2 = ~9.5hrs Stock S2 KE2 + Juice Defender free version = ~13-20+hrs Stock S2 KE2 + Juice Defender free version + XP8000 = ~52+hrs Setup ADW Launcher homescreen based Brightness = 0-10% Optus Live wallpaper changed to normal wallpaper Wifi Enabled = all the time connected to VOIP GPS Disabled Bluetooth Disabled Background Sync Enabled 3x IMAP email accounts checked at 1hr, 4hr and 6 hour intervals respectively Server Monitor app = checks 2 servers uptime every 30-60 mins and logs results Angry Birds = ~6.5hrs total play time Music = ~3hrs total play time Web browsing and Android Market browse/downloading via wifi Break down * Less than <50% battery life = enters into power saving mode Day 1: 1:01 AM - 100% Full charge 1:49 AM - 4:49 AM - tried leaving XP8000 connected after 100% but seems it stops charging after 100% so rest of tests removed XP8000 after charged to 100%. But graphs still report S2 being connected to USB/power. 5:06 AM - @58% rate of power usage ~170mah - 1st XP8000 charge up started 6:44 AM - 100% charged via XP8000 @ ~425mah 2:39 PM - @24% rate of power usage ~320mah - 2nd XP8000 charge up started 5:59 PM - 100% charged via XP8000 @ ~377mah Day 2: 6:20 AM - @15% rate of power usage ~114mah - 3rd XP8000 charge up started 9:04 AM - 95% charged via XP8000 @483mah, XP8000 emptied no more reserve power [Uptime: ~32hrs ] Day 3: 5:02 AM - @6% rate of power usage ~74mah - 4th XP8000 charge up started [Uptime: ~52hrs ] 8:40 AM - 100% charged via XP8000 @427mah - was asleep for this one so it's approximate time based on battery graph here. The XP8000 is rated at 30WH capacity, so not sure of the maths as it seems 8000mah fell short in expected amount of extra battery life if you go by the software graphs (yeah probably not entirely acrurate). Day 1 @100% Day 3 hitting 6% battery life left I'd imagine with KE7 or 2.3.4, I'd be pushing 60-80+hrs with S2 + XP8000 ? On a average 8-12hr work/away from home day, with KE2 firmware you'd be running 1-4hr deficit per day (need to use 8hrs of XP8000 reserve power). So with 32 hours provided by XP8000, you could end up only charging Samsung Galaxy S2 every 4 days via mains AC adaptor (longer with KE7/2.3.4 firmwares I guess). So could hook up S2 to XP8000 at work, away from home, in the car etc I suppose.