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Comment by qd6pwu4 | Hacker News Reader

Last week, I replaced the battery for my iPhone6s, because the old battery has almost died. After that, it becomes much faster than before. The old battery often shuts down even though there is 50% left. My phone is on the recall list but I can never book a slot for replacing the battery in any Apple store here in Hangzhou, China. They are always full. Very disappointed with Apple's service. Then I bought a third-party battery on Taobao for less than 20$ and replaced it by myself. When my phone turns on again, I feel it's so fast and smooth. Then I realized iphone drops cpu frequency when battery dies. The new battery is 2200mAh, 550mAh larger than original. Now my phone can last a whole day under normal use.

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I wonder if Android does the same thing. My understanding if batteries is that @ 100% charge they are going to sit around a certain voltage. They will never stay at the maximum voltage under use though. Is it possible that the OS needs to drop the CPU freq due to the voltage requirements (which maybe a 70% healthy battery could NEVER hit), and ultimately stressing/draining the battery quicker at higher frequencies.

Electrical engineering already figured out that the voltage level vary with the charging level. It's accounted for when designing a circuit.

The voltage specification you see written on batteries is actually the discharged voltage.

For instance a car battery is known as 12V. That's the uncharged voltage, it's 14V at full charge.

LiPo batteries generally supply from 4.2V to 3.7V from a fully charged state to a fully discharged state. Modern CPUs run at under 2V. If the battery was directly connected to the CPU, the CPU would fry.

https://en.m.wikipedia.org/wiki/Buck_converter

That being said, it's conceiveable that a worn out battery might not be able to supply enough power to run the CPU at higher clock speeds.

Not to nit-pick, but 3.7v is the nominal cell voltage. They can supply power down to 3.3v safely. Fully discharged is around 3.0v.

Ah yes, thanks for the correction.

How do you physically replace the iPhone battery? And where do you buy the replacement?

For both of those: see ifixit.com .

I trust their batteries and their directions.

Definitely. I replaced a screen on a 4 using an iFixit guide. Very detailed.

A great tip I used, iPhone parts are so small and fiddly. Print out the instructions, and at each step, if you remove screws, tape them to the whitespace beside each step. Then when you reassemble in reverse order, you know exactly which screws to use.

I bought the battery and replacement kit on Taobao, like China's ebay. Just pull up the front panel and replace the battery.

Do Apple Stores work differently in China? In the United States I have been able to call about a week out and get devices serviced in the past.

I went to the Apple store, they will only replace battery for me after I book a slot on the Internet. But I can never successfully do that.

So you don't have internet or their website doesn't work? Maybe there are no times available?

Their website always says no times available.

Where did you find that battery? I located one on ifixit but it's only 1558mAh. 2200mAh sounds like a crazy improvement.

On Taobao, produced by a Chinese third-party manufacturer.

And yet they put more staff and space for communities , not for support.

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