In late December Apple dropped the price of its battery replacements to any customer with an iPhone 6 or newer regardless of diagnostic result for just $29 instead of the usual $79. According to new fine print on its iPhone service pricing page Apple has confirmed that this policy can only be taken advantage of once, .
After you’ve had your iPhone’s battery replaced once this year, the device must then fail the diagnostic test to qualify for any additional battery replacements for $29. If the test passes, a customer can still choose to have the battery replaced, but Apple’s standard $79 fee applies. Apple says iPhone batteries are designed to retain up to 80 percent of their original capacity at 500 complete charge cycles, and this will most likely the primary benchmark for its diagnostic test, but results may vary.
The clause was probable added to stop customers who may have planned on taking advantage of the $29 deal now, and then again near the end of 2018, as the combined $58 cost for two replacements would still be cheaper than the standard $79.