Im wanting to buy a new battery because my phone won't last all day on a single charge. When buying though i noticed another stock would cost me 40 dollars. I was looking on amazon and they had batteries like these Amazon.com: QCELL 2X SAMSUNG GALAXY SIII 2100MAH BATTERY + FREE UNIVERSAL BATTERY CHARGER (COMPATIBLE WITH SAMSUNG GALAXY S3 GT-I9300, SPRINT L710, VERIZON I535, T-MOBILE T999, AT&T SAMSUNG I747, U.S. CELLULAR R530)**WITH NFC CAPABILITIES FOR S BEAM cheap and even comes with a charger. I dont want to have problems so anyone had any problems with these aftermarket models? My last question is should i go with a bigger battery? instead of the 2100? I use an otterbox case so not sure this is even possible?