JC Battery Flex TAG for iPhone 12 / 12 Pro

Service battery flex from JC for Apple iPhone 12 / 12 Pro.

Update FIX for iOS version 17.4

After updating to version 17.4, it is necessary to use the 3U Tools program to set the battery capacity to 100% and 0 cycles.

Download the 3U Tools program here.
*It has not been possible to verify how the battery capacity percentage will decrease over time. Once we have tested it for a sufficient period, we will update this information.

Articles for iPhone 11 and newer still require the use of the TAG-ON flex.

*This guide also works on older versions of iOS.

1. Back up the phone's memory to a computer. In the new procedure, it is necessary to flash the system via 3U Tools and then restore the data.
2. Set the original battery (or a battery with the original BMS flex) using the TAG-ON Flex programmer to a capacity of 100% and decrease the cycle count to 0.
3. Thoroughly solder the original flex to the new cell and permanently attach the Tag-On Flex.
4. Insert a different battery than the original into the phone and turn it on to trigger the message about a non-original battery in the settings – battery – battery condition and charging.
5. Turn off the device, remove the non-original battery, insert the cell with the original BMS flex and Tag-on Flex with adjusted capacity and cycle count into the phone.
6. Connect the phone via cable to 3U Tools, download iOS 17.4, select Quick Flash Mode, download the iOS 17.4 version, check the Fix battery health during Flash option, and then click the blue Flash button (see image).
7. After installation, activate the phone and check in settings – battery – battery condition and charging.
8. Done, you can now restore the backup from step 1.