Chosen Solution
I bought the ifixit iPhone 6 battery repair kit and successfully installed the new battery. My issue is my phone still dies when it reaches around 50% battery life. When i plug it in and it boots back up the battery shows 1-6% on it. This only started being an issue after about a month of using the new battery, although the new battery never let me use my phone to 1%, always dying around 10-15% from the start.
It could be a poor quality replacement battery. To be certain, use a battery utility, such as coconutBattery (for Mac) or 3uTools (for Windows). It will tell you what the health of the battery is. Anything less than 80% of design capacity will require replacement. After testing the battery, I would contact iFixit Support to see about a replacement. It is possible that you have an issue on the logic board so if another replacement battery behaves the same way, that is where I would look for the problem.
maybe the battery is not in good condition.
