Perhaps an iPhone never ‘runs on the charger’.
The power management system is centered on the battery. The battery is the most trustworthy power source. It cannot be suddenly unplugged or decide (without warning) to reduce power delivery because another device was plugged into the next USB port on the charger.
This is my understanding too, as it’s similar to the way Apple notebooks have also worked for a while (hence the throttling when the battery is removed or bad). Phone wise, I imagine it’s also simpler to run it this way, especially on newer phones with contactless charging via Qi. IIRC, Apple’s taking another step to replace a 3rd party chip with their own in the power management iOS side currently.
Main device difference is the size of the batteries, and Apple’s deeper control of the hardware on the iOS side. Key thing to remember here is Apple also did move to manufacturing their own batteries in both notebooks and iOS devices a while back, which likely also factors in to the situation.
Apple’s been pushing mobile CPU boundaries for a while now, and their lead in the space is exposing them to unknown risks. Risks that will take a few years to fully fix with new silicon, so software fills those gaps. I’ve heard rumblings there’s times Apple’s custom SoC can spike to 10W power draws from near idle for some tasks, and it seems like iOS 10.2.1 was one of those gap fillers.
https://support.apple.com/en-us/HT208387 has a lot of interesting details to parse, especially the “In cases that require more extreme forms of this power management, the user may notice effects” section.
Overall this is a situation Apple caught legitimate anger due to their silence or whispers. When the 6s esposed the issue, combined with a legitimate bad batch of batteries, they hinted there was more to the issue with 10.2.1. However those hints only came via one line in the patch notes, along with statements to two Apple journalists. In classic telephone game problems, those journalists didn’t relay the full context properly to let Apple’s admittance that they throttle the iPhone 6 and 6s due to battery conditions become common knowledge among owners.
Thus the myth of “Apple intentionally slows old phones to force upgrades” grew a bit since they were unintentionally doing so after being backed into a corner with their batteries. When folks were running benchmarks, they could induce one of the rare behaviors that exposes the throttling so clearly. With a lack of clear communication before, it blew up into the ad revenue clickbait news cycle. Apple plays it too conservatively at times, and their reactions to situations like this I feel can still improve a lot.
My take is that Apple is ‘doing the right thing’ here. Clarity, humility, and rather fair pricing on new genuine Apple batteries, installed and with an Apple battery warranty. This may cut into aftermarket replacement battery sales.
Agreed. And it’s already having an impact on aftermarkets. iFixit dropped their battery replacement kit to $29. This also includes phones older then the iPhone 6, so any do-it-yourself types have a good quality 3rd party source for older units still in use.
I feel under Jobs, they’d keep the $29 battery program for 5 years up front. Under Cook, I’m not so sure and feel they may extend it once but ultimately return to the old $79 cost sometime in 2019. I feel Cook’s old operations side gets in the way at times, especially when Apple’s sitting on the massive cash horde they continue to grow.