For years I told people they were crazy for thinking that Apple was purposely slowing down older iPhones in an effort to force customers to upgrade to a new device.

It turns out I was wrong.

Apple admitted on Wednesday that it cuts the processing power of older iPhones with aging batteries in an effort to keep them running as smoothly as possible. In other words, the processors on some phones, including the iPhone 6, iPhone 6s and even the iPhone 7, aren't always running at full power as they age.

That helps explain why running apps and switching apps can feel much slower than they once did.

Apple has a reason for this, but it's the wrong approach. Rather than intentionally slowing devices to keep them from shutting down (as the company explained to TechCrunch in a story on Wednesday), it should do right by its customers who expect their pricey iPhones to last more than a couple of years.

Last year Apple had to respond to widespread issues with the iPhone 6s battery. Owners of that device started to report that it would shut down at random times, even if the battery wasn't completely depleted.

To mitigate this issue and similar ones, particularly when batteries get old and begin to drain more quickly, Apple has started to algorithmically alter how the phone uses power. The phone feels slower because it actually is slower. Apple says this improves safety.

Here's what Apple told CNBC on Wednesday:

"Lithium-ion batteries become less capable of supplying peak current demands when in cold conditions, have a low battery charge or as they age over time, which can result in the device unexpectedly shutting down to protect its electronic components."

But here's another idea.

If Apple is going to drop the performance of a smartphone because of poor battery life, it should replace an iPhone's battery at no charge. Sure it's an expensive undertaking for Apple, but a user should be guaranteed a certain level of performance for the lifetime of a product, until Apple stops supporting it with new software. Apple did this for customers who were hurt by the iPhone 6 battery problems.

Consumers will otherwise be encouraged to download new versions of iOS that will only require more processing power, which will slow things down. They'll then see a further deterioration in performance when Apple throttles the processor.

Apple is putting its reputation for great customer service and support at risk. One free battery upgrade would help preserve that goodwill.