Thursday, March 15, 2018 [Tweets] [Favorites]

iPhone Wireless Phone Charging Comes at a Cost: Your Battery

Sasha Lekach:

Kingsley-Hughes determined — based on Apple’s claim that an iPhone battery is “designed to retain up to 80 percent of its original capacity at 500 complete charge cycles” — that his phone would hit 500 charges in about a year and a half. Most phones are expected to keep a charge at 80 percent for two or three years of use.

In about six months, he’s already hit 135 charging cycles. He looked at his charging behavior and realized that since switching over to a wireless charging plate about six months ago, he was eating up his charges at an alarming rate. Now instead of the cord bearing the brunt of power duties, his battery is constantly working to charge. It’s a losing battle.

Other phone users on Android devices have their suspicions about heavy battery wear on the devices with inductive charging.

Dan Masters:

Fantastic. Basically, if you don’t want your phone throttled in less than a year, don’t use wireless charging.

iPhone wireless phone charging comes at a cost: battery health

My iPhone SE does not have wireless charging, but according to coconutBattery it has already dropped to less than 80% capacity after less than a year.

Previously: iPhone Charging Speeds Compared, iPhone 8, Qi Wireless Charging, and the Challenge of Open, Apple’s Message to Customers About iPhone Batteries and Performance.

Update (2018-03-29): I now realize I was misinterpreting coconutBattery’s display. My iPhone SE battery actually retains its full design capacity.

Update (2018-04-06): See also: Accidental Tech Podcast.


The linked articles (and tweet) are wrong.
The article says iPhone batteries are "designed to retain up to 80 percent of its original capacity at 500 complete charge cycles." The article you linked to acts like "500 cycles" is the important phrase, it isn't. The important part of that phrase is "up to 80 percent". 500 charges is simply a way to estimate when that 80% level might be hit. And it isn't "500 charges", it is "500 complete charge cycles" i.e. charging battery from a low state to full state, usually overnight in normal usage (which is why the original author said he estimated 500 charges would be 1.5 years).
That is very different than charging constantly throughout the day, as the original author states ("I've become accustomed to leaving my iPhone in a wireless charger when I'm not using it"). That runs up the number of charges but they aren't be "complete charge cycles", which (again) isn't the number that matters anyway. The articles (and equally misguided/clickbait tweet) never bother to mention the battery health percentage, the only number that actually matters in the throttling discussion.
I only charge my iPhone on an inductive charging pad on my desk at work and when plugged into my car while driving. I'm guessing it has quite a few "charges" by now but that number doesn't matter. The number that matters is the Battery Health. After about 6 months of inductive Qi charging all day every day, my iPhone 8 Plus battery is still at 99% health.

And this is nonsense: "Now instead of the cord bearing the brunt of power duties, his battery is constantly working to charge."
And this: "While some charging tools may automatically turn off when the phone is juiced up to prevent over-charging, it's still a heavy burden on the battery despite the helpful feature." Really? I'm surprised you linked to this at all.

@sirshannon There may be problems with the linked article. I don’t know. If it ends up getting debunked, I still think it’s worth linking to because people should know that it’s not true.

I don’t see anything in the article that suggests it is not talking about complete charge cycles.

That said, I’m not sure it’s only the number of complete charge cycles the matters. I’ve long heard, from many sources, that too-frequent charging (by plugging in the phone) is not optimal for the battery.

Also, from what I’ve heard—I’m no battery expert—wireless charging does put more strain on the battery than using a cord, perhaps because the temperature is higher or it spends more time in a charging state (since wireless charging is slower).

I was curious about whether inductive charging would be better for a battery overall, because it charges at a slower rate. This is the first I've heard that it doesn't spare the battery from use while charging, and I'd like to see that confirmed elsewhere.

I've been using a Qi charger with an iPhone X since November, almost exclusively for overnight charging, because it's by my bed. CoconutBattery says the phone is at 97 charge cycles. Over about 120 days, with it typically at about 40% power by the end of the day, that's not out of line with what I'd expect.

Slower charging is usually better for lithium-ion battery health, all else equal. If wireless charging does turn out to wear down batteries more quickly, it would be from some other aspect of the technology.

...unless the rate of charge is so low that using the device while charging causes the battery to fluctuate between charge/use states?

I'm with sirshannon, this sounds very odd. Like remmah says, slower charging should be better. And how you charge your phone should not have any impact on its charge cycles. You're not magically going through more charge cycles just because you don't use a cable to charge your phone. You're using the same amount of power overall, and thus also charging it the same amount.

> since switching over to a wireless charging plate about six months ago, he was eating up his charges at an alarming rate

What does that even mean? I understand the individual words in that sentence, but I don't understand how they make any kind of sense when put together like that. Going to wireless charging made his phone use more power?

> In about six months, he’s already hit 135 charging cycles

This seems completely normal. Six months ~= 180 days, so one full charge holds out for about 1 1/3 days, which sounds exactly like what you'd expect.

To me, this sounds like mass hysteria, not like an actual problem. I mean, maybe it is, you never know, it's just really, really strange all around.

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