After the iPhone 6S battery issue was discovered, Apple stepped up and announced the free battery replacement program for eligible units. Not all iPhone 6S units have faulty batteries and there is an easy method to check if an iPhone 6S unit is eligible for the program.
iPhone 6S Free Battery Replacement Program
Apple originally mentioned that the affected iPhone 6S models were manufactured between September and October 2015. That was all the details provided by the company and users were asked to take the device to the service center.
If the iPhone 6S unit was found to be eligible, the customer would get a free battery replacement. The issue with the old battery was that it would suddenly shut down the iPhone even if there was enough charge. According to BGR, the issue is also present in other iPhones, but only the iPhone 6S is eligible for a free repair.
Checking iPhone 6S Eligibility For Apple Battery Replacement Program
Thanks to an easy method reported by 9to5Mac, it is possible to check if an iPhone 6S is eligible for free battery repair. On the iPhone, head over to "Settings>General>About" and check the Serial number. If any of the following combinations are present (Q3, Q4, Q5, Q6, Q7, Q8, Q9, QC, QD, QF, QG, QH, QJ), then the iPhone is eligible and should be taken to the service center.
Even if the iPhone 6S is not showing any signs of the battery issue, but has one of the combinations, it is best that the battery is replaced for free. If one of the combinations is not shown on the iPhone but the device is still showing symptoms, then customers should contact Apple.
Apple will provide up to three years of warranty for battery replacements after the date of purchase. Out of warranty customers will not have to worry if their device is affected as they can also get the replacement for free.