Apple will give users the option to turn off a feature that temporarily slows down older iPhones in order to prevent unexpected shutdowns, chief executive Tim Cook has said.

The new option is likely to arrive in March, as part of the next update to iOS 11. "you don't want it, you can turn it off," Cook told ABC News. The CEO maintains, however, that Apple "don't recommend" users take advantage of the ability to disable the slowdown.

Alongside the option to turn off the slowdown, Apple will also introduce much more detailed monitoring of battery health for users. Currently, iOS will warn users if their battery is substantially decayed, but will not notify them of partial aging -- even if that aging is severe enough to warrant the slowdown. With the update, Cook said, "We're going to give people the visibility of the health of their battery so it's very, very transparent -- this hasn't been done before."

Before Apple released iOS 10.2.1 in 2016, older iPhones were frequently hit with an issue that caused a spontaneous shutdown if the battery's voltage output dropped below a certain threshold -- which occurred more frequently when the battery got old, cold, or ran low on charge.

In that update, the company tweaked the iPhones 6, 6s and SE to instead slow down the processor when the voltage dropped. For intensive use, this resulted in the phone as a whole slowing down, but prevented it from shutting down. In 2017, with iOS 11.2, Apple made the same update to iPhone7 devices.

But the company did not notify users of the change, leaving it to be discovered by individuals running performance tests on their phone. The resulting uproar saw the company accused of deliberately slowing down older devices to encourage users to buy new ones, a practice known as "planned obsolescence."

In December, Apple released an open letter explaining the updates, and promised a number of changes, including the upcoming software update and a reduction in price of the company's battery exchange program for users with affected models.