A couple of you asked about the Mugen Power 4000mAH extended battery - since I bought it, I thought I would share a couple of impressions. But first, let me describe how I run the phone: - the latest version of Broken Out - set to 1836mhz w/smartassv2 governor in AnTuTu CPU Master... - 3G on / LTE off (no coverage here in the woods) - BT moderate use (streaming media player to car and home units) - WIFI on most of the time - Sync on most of the time - Auto updates in market - on - Screen - AUTO Usage: Many phone calls. Google lookups. Youtube. Streaming audio usage. Lots of web usage for stock and news stuff. Some gaming...I would say moderate to heavy. Typical day with STOCK BATTERY: 7am unplug - 100% 12pm - 69% 3pm - 40% 6pm - 17% 9pm - 3% - (charge) Typical day with Mugen Power Extended Battery: 7am unplug - 100% 12pm - 93% 3pm - 83% 6pm - 67% 9pm - 52% (set to airplane mode at night) ...next day 7am - 50% (turn off airplane mode) 12pm - 40% 3pm - 30% 6pm - 10% 9pm - 6% (charge) (If I configured Juice Defender on the phone, and ran it at 1512mhz - the above stats would improve probably to 3 days worth of charge.) The battery door fits nicely - and it is fairly high quality. The battery does not get hot - and surprisingly, is not heavy. The phone is about as thick as an LG ALLY with this extended battery setup. Overall, there are really no cons except the price - but if you are an average to heavy phone user - this might be worth it for you. I bought it here. I paid $79 on sale. Hope this helps....some of you out there thinking about extended batteries of any kind.