Worked where others failed

My Problem

Poor life with old battery - would go from 100% to 60% in 10-15 minutes and drop from 40% to zero out in the cold

My Fix

Replacement was straight forward

My Advice

Fast shipment, installed with 63% battery life, took about 6 hours to get below 10% and charged to 100% overnight. New battery life now much better than old one. Had tried 2 other iphone 4 batteries (ebay and amazon) neither worked correctly - kept turning phone off and turning it back on without showing correct battery life percent and acted flakey during charge. Ifixit one did the trick.