Updated September 2026: in 2020, disappointed by the iPhone 12's price, I was still using an iPhone 6 that had slowed, and noted Apple had acknowledged throttling older iPhones with weak batteries. I have rewritten it into an explainer on iPhone performance management and battery health.
I had been using an iPhone 6 for years, and it no longer worked as it should. Apple had admitted slowing older iPhones with degraded batteries, which added to my frustration when the iPhone 12's price put an upgrade out of reach.
Why did Apple slow older iPhones?
In 2017 Apple confirmed that iOS managed performance on some older iPhones whose batteries had degraded, to prevent unexpected shutdowns when the battery could not deliver peak power. It had not explained this clearly to users, which led to criticism, a discounted battery replacement programme, and legal settlements in several countries.
How do you check your iPhone's battery health?
Go to Settings, then Battery, then Battery Health. It shows the maximum capacity compared with new, and whether performance management is active. On recent models it also shows the cycle count.
Can you turn performance management off?
On supported models, yes, from the same screen, but the setting returns after an unexpected shutdown. The better fix is replacing the battery, which removes the need for throttling.
When should you replace the battery?
- When maximum capacity falls below about 80 percent.
- When the phone shuts down unexpectedly.
- When performance management has been applied.
A battery replacement at an authorised service provider is much cheaper than a new phone and can make an older iPhone feel responsive again.
When is it better to upgrade?
When the phone no longer receives iOS updates, as with the iPhone 6. A new battery then helps speed but not security.
How do you make a battery last longer?
Avoid heat, keep iOS updated, and leave Optimised Battery Charging on so the phone does not sit at 100 percent overnight. On recent iPhones you can also set a charging limit.
What changed for later models?
Apple now documents battery management openly, and newer iPhones handle peak power better.