Pixel Charging Limit To 80%

PGrey

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I have, even before this type of feature was common and unplugging manually. Another life extending benefit not often mentioned is having this feature built in means you can basically treat the phone like a mains powered device. Once the battery hits 80% and stops charging, the phone runs strictly from the charger, reducing the amount of cycles (and thus cycle related degradation) it goes through. Great if you're a heavy user.
Can you point to the spec on this part, or something similar, I'm definitely curious about the circuit/algo design on this.
If they're regulating it this cleanly (zero battery transition/draw while plugged in at say 80%), why not allow the same at say 95%?
 

charlieparsons67

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Nov 14, 2024
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I don't understand why anyone would use this.
Hi I see a lot of different opinions out there. But I can tell you my experience. I use something called chargie. It is a device that goes in between the brick and the phone it connects to the phone by Bluetooth so you can control the settings via app. I have it set to limit my charge to 80 and the newest version charges at I think a max of 7watts. Which is plenty for overnight charging and if I need a rapid charge I just take it off. So I have an old pixel 3a that I now use as a security camera. It has always had a chargie on it since it was bought brand new. So always 80 percent charge. According to accubattery that battery is still holding 95 percent of it's capacity. So that phone is 6 years old and the battery has only degraded by 5 percent. It might be a little bit more I haven't checked it in a long time. Earlier this year my p6 pro broke and I had to use the old 3a for a few weeks while I got my 8 pro. The battery on my 3a lasted all day with moderate use. In my opinion that's a pretty good performance for a 6 year old phone. And that's why I only charge my phones to 80. Other people might have different experiences and that's fine I'm just telling you mine.
 

Mooncatt

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Can you point to the spec on this part, or something similar, I'm definitely curious about the circuit/algo design on this.
If they're regulating it this cleanly (zero battery transition/draw while plugged in at say 80%), why not allow the same at say 95%?

On my Xperia 1V, I can select 80% or 90% as the cutoff. I keep it at 80% because it's a bit less wear on the battery. Charge level makes a difference. Battery University covers this in a roundabout way in this article.


Look at table 3, which shows how storing a battery at different charge levels (and temps, for that matter) can affect the capacity after long term storage. Setting a charge limit is effectively the same as putting the battery into storage, if I'm understanding things correctly, which is how that article is relatable here. Also notice that with elevated temps, battery capacity goes down quicker, but that excess wear is mitigated somewhat if it is at a lower charge level. Since a phone can get warm, and that I'm sometimes working in a relatively hot environment, 80% gives me better piece of mind.

Here's what my battery care page says when set to always on, limiting it to 80%.

IMG_20241114_164413.jpg

And once I hit 80%, charging stops just like it would when it hits 100%. I can see that on Ampere. At this point, the charge rate drops to zero. Ampere sees that it's plugged in, but the charge current goes to nothing and stays there from then. Occasionally it'll drop to 79%, but that's it.

IMG_20241114_170930.jpg
 

PGrey

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And once I hit 80%, charging stops just like it would when it hits 100%. I can see that on Ampere. At this point, the charge rate drops to zero. Ampere sees that it's plugged in, but the charge current goes to nothing and stays there from then. Occasionally it'll drop to 79%, but that's it.
Yep, this is what I figured was going on.
It's still discharging/charging, steadily, just not charging it to 100%, so you're cycling 79-80-79-80... instead of 99-100-99-100...
I don't think either of these is good for the battery, in terms of longevity, but certainly the 80% is better. A much better always-plugged-in algorithm (particularly for say something like a laptop that would tend to fit this use-case more aptly) would do something like 100%, and then switch to all mains power, until the battery slowly dropped to maybe 85% or so (week or two, whatever) and then top back to 100% (or if the user initiated, say before an anticipated long day of no plug-in work).
This would avoid most depth-discharge cycles and overheating, in this fairly common use-case.
The problem with this is that batteries/laptops (phones/tablets/whatever) would last too long for the market side of things.
 
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Mooncatt

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Yep, this is what I figured was going on.
It's still discharging/charging, steadily, just not charging it to 100%, so you're cycling 79-80-79-80... instead of 99-100-99-100...

That is not what it's doing. If that were the case, then it would show up as a positive charging current. Charging current is zero, and the occasional drop to 79% is just that, occasional. When it does happen, it never goes back up to 80% if it is still plugged in. If I unplug and plug back in, then it may do so, but I've never tested that idea. When I unplug, I leave it unplugged until around 30% just so I'm not also overly cycling the USB port and risking wearing out the connection.
 

mustang7757

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I'm not a fan of trickle charging which is an option on my Samsung especially on lithium ion battery, I have it cut power once it reaches 80% if you have it cut off at 95% like my iPhone that's ok also just going degrade little faster then 80% cutoff

You can see the options below for my s24u
684236551b63cf5b0460ac8202025eff.jpg
 

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