Chosen Solution
I already bout a new battery for my iPhone 6 and it’s not working so well… Is going down more quickly then I expected… Did I do something wrong at putting the battery?
Likely a poor quality battery. You can exchange it for a working battery. I would suggest an oem quality one Like this iPhone 6 Battery If you’re unsure about your install, use this iPhone 6 Battery Replacement
download ibackupbot and look under “more information” for the device, it will give you details on the battery such as charge cycles and capacity/expected capacity. Since it sounds like you purchased a “new” battery it should have very near 0 charge cycles on it. Oftentimes inexpensive batteries are actually reclaimed batteries out of parted out devices. Thats why its important to buy a quality battery. I really suspect you got a poor quality or old battery. If that is not the case, you’ve got an app killing your battery somewhere.
