Hey guys,

I just installed an iFixit battery in my daughter's iPhone 7 with iOS 12.1.2 and the Battery Health feature works. Maybe apple corrected this or the battery is compatible with this feature now.

I received this straight from iFixit support:

Thank you for contacting us about your battery health!

We are aware that Apple's iOS 11.3 update includes a beta release of the Battery Health feature. Some customers have already reported the same scenario with their device -- the battery is unable to determine it's current health state -- which has lead to them believing that their battery is defective. This is not indicative of a defective battery, simply iOS 11.3's lack of ability to read the diagnostic data from the battery at this time.

It is our current understanding that this feature may not operate with iFixit batteries as our batteries are not manufactured by Apple. That being said, iOS 11.3 is so new that it is possible there will be a patch coming soon that may enable your iFixit battery to work with this feature. We encountered a similar issue in the last Apple update, 11.2, where we saw a rise in users report sudden touch response issues after updating their phones to iOS 11.2 (which even affected users who had never replaced components on their device). Apple later rolled out an update that corrected this issue.

If the battery you have installed is not prematurely shutting down or otherwise behaving strangely, you can try rolling back your iOS to 11.2 and wait until Apple releases a patch to fix this issue.

Thanks!

iFixit Support

My response was:

I just hope they do, with iOS 11.3, the device will have performance management. I don’t have problems with the iFixit batteries but If its not working you can’t disable the slowdowns in the Battery Health screen under Peak Performance Capability since is not displaying anything.

Basically all phones with aftermarket batteries will start slowing down when battery starts loosing capacity while original battery users will have peak performance until is time to replace the battery.

Thanks for the detailed reply