How to check battery health on a vintage iPad Air 2?

The battery health feature is exclusive to iOS for iPhone, inclusion of this feature being relatively recent.

iOS/iPadOS for iPad has never had the Battery Health feature - most likely because iPad batteries are both considerably larger and have a much longer service life. 

An iPad battery is rated to maintain at least 80% of its initial capacity after 1000 full charge/discharge cycles - whereas an iPhone is rated to have 80% of initial capacity after 500 full cycles.

There are software packages available that can access battery cycle count. Popular choices for Mac are Coconut Battery and iMazing - whereas iMazing is available for PC.

https://www.coconut-flavour.com/coconutbattery/

These support pages should help with troubleshooting battery and charging issues:

Charge and monitor the iPad battery - Apple Support

If your iPad won't charge – Apple Support

Troubleshooting generally requires substitution of the Power Adapter and cable for another known-good item. Most models of iPad require a Power Adapter rated at 12W or greater to reliably charge. 5W Power Adapters intended for older models of iPhone are inadequate to charge an iPad; if the iPad charges at all, charging will be very slow.

Be aware that many computer USB ports cannot source sufficient power to charge an iPad. Unless explicitly designed for charging connected devices, computer USB ports are typically limited to 0.5-1A @5V (i.e., 2.5-5.0W).

If you continue to experience difficulties when using an appropriate Power Adapter of 12W or greater, you might be best advised to seek assistance directly from from Apple Support. You can contact the Support Team using the Support link at top-right or bottom-left of this page. Alternatively, if you have access to another Apple device, you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/app/apple-support/id1130498044

You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad, Power Adapter and cable(s):

Genius Bar Reservation and Apple Support Options - Apple

The Battery Life app on the App Store used to be able to provide something. Someone mentioned coconutBattery, which is what I used. Other than that, an official Apple diagnostic (can be remote or in person) can pull the official battery health reading. I had that done once and it was way different than the value I saw from coconutBattery.

But if it’s under 80% or there’s some other battery fault, and it’s in decent working and cosmetic shape, you may be able to get a replacement. It’s still available for the iPad Air 2 for $119 plus tax in the United States. Pricing is different in other countries. This has the estimator at the bottom of the page.

iPad Repair & Service - Apple Support

But it has to work and not have any serious cosmetic flaws to be eligible for a battery service replacement. I’ve had mine denied because the case had bent after being dropped hard, even in an Otterbox case. I was told that I could pay for an “other damage” replacement that cost what I paid brand new. An Apple employee also logged the cosmetic condition in a database so that I wouldn’t be able to get a second opinion in the future to try and get a battery service replacement.

BellaMiaow wrote:

Thanks. The iPad is in perfect condition other than the battery issue, so I'll make a Genius appointment.

Good luck then. Apple doesn’t actually replace the battery per se. For the most part the only hardware service Apple provides for any iPad model is replacement with what’s nicknamed a “white box unit”, whether it’s a warranty/AppleCare issue, an “other damage” replacement, or a battery service. There are some hints that Apple may be replacing batteries and returning devices for some newer iPad models. The general idea with battery replacement is that the good condition iPad will have parts that are usable for making new refurbished iPads, although part of it may just be as a courtesy for customers and a high level of service. I understand that replacements typically have new displays and cases, as well as new batteries. They can possibly be completely new, but unlikely for older models like an iPad Air 2. They almost always replace only with the identical model including storage capacity and color. The replacements have a model number that’s modified to start with N, while Apple has M for devices sold new at retail.

It would be a good idea to have a backup of the iPad to a computer (Mac or PC) in order to restore that backup to the replacement. When I got a warranty replacement (came in a plain white box that I didn’t get to keep and no cables) I wasn’t given the opportunity to do a transfer at the Apple Store, but I had a recent backup that restored everything I needed. My father got a battery replacement for his iPad Pro that cost something like $800, where the battery replacement was $99 at the time. He was shocked that they gave him a practically new iPad Pro, and for him he was fortunate that they helped him with the transfer. He’s never backed it up, although he might have paid for extra iCloud storage.

BellaMiaow wrote:

Oh, yes, it's always important to back up a device before taking it in! Thanks for the reminder :-)

Yes. I've heard of Apple replacing computers or even iPhones outright at the same price as a battery replacement, and some were caught unaware thinking they'd get it back with just a new battery and didn't back it up to restore later.

But again - good luck. I can just say that while I couldn't tell what was inside, my replacement iPad was otherwise pristine looking. I would have thought that it was new, which was a distinct possibility.

Check Settings > Battery.