S21 Ultra - Why do the last 5% of my battery drains so fast?

[Android Central Question]

Over the past month or 2, I have been experiencing a strange bug with my S21 Ultra.

Every time I reach the warning that I have 5% battery remaining, the battery starts draining incredibly fast. I'm not kidding when I say that it lasts for 1 or 2 minutes of on-screen time.

I don't know if there's a fix, or if it's something that happens to anyone else, but is really annoying. The phone usually lasts between 5 or 6 hours of on-screen time, so it doesn't make any sense for the last 5% to last just a minute.

 

[trucker3573]

Crazy thought….don’t let it get that far down. Letting it basically get to zero before you charge will greatly reduce battery life. Of course it is going to die very fast when it is basically already dead…sorry but lol. World of difference between 95-90% then 5%-0. 5% for all intents and purposes might as well be zero.

 

[mustang7757]

Yes it will do that , you should charge it but if you really want the 5% to last don't know what for... put it in power saving mode , just don't make this a habit.


I'll leave a Link to register so you can communicate here as a guest account you can only post questions but can't reply

https://forums.androidcentral.com/showthread.php?t=409154

 

[B. Diddy]

Welcome to Android Central! Battery sensor software can get more inaccurate as you get close to zero. I completely agree with trucker3573 -- don't make it a habit of letting your battery get that low, or you'll find that it can no longer hold a charge well as early as 6 months down the line. As a rule of thumb, start charging once the battery gets to around 30% or so.

 

[Mooncatt]

Your phone requires a specific amount of wattage to run, which is voltage x amperage. As a battery drains, voltage goes down. To compensate, amperage must come up when the voltage gets on the lower end of the spectrum to compensate. As others have said, it's not good to let a Li-ion battery get so low, and that's because it accelerates wear internally. When that happens, the battery can no longer keep up as well, which is why you now see a reduced run time at those lower percentages. As the wear continues, you'll start seeing immediate shutdowns at 5%, 10%, or even 20% as if the battery was straight up disconnected.

Long story short, this isn't a bug. You've been abusing your battery whether you knew it or not. At this point there is probably little you can do to slow the wear, even with good charging habits (those are preventative measures, not fixes). When your battery loses too much capacity to be bearable, you'll need to replace it, if not the entire phone. At that point, try to keep your new battery between 40-80% or so to limit the amount of usage wear caused.

 

[cperezsandit95]

Hi, I already registered so I could answer your replies. Thanks a lot to the 4 of you for the feedback! I didn't know that about batteries, I won't let my battery drain that much now.

 

[Mooncatt]

Hi, I already registered so I could answer your replies. Thanks a lot to the 4 of you for the feedback! I didn't know that about batteries, I won't let my battery drain that much now.

Welcome, and thanks for joining. If you want to get into the technical nitty gritty, this article covers a lot on the variables that can impact Li-ion batteries, and is what the 40-80% guideline is based on.

https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries

 

[mustang7757]

Hi, I already registered so I could answer your replies. Thanks a lot to the 4 of you for the feedback! I didn't know that about batteries, I won't let my battery drain that much now.

Hi, welcome to AC!
Mooncatt method is a good way to preserve your battery for years , my experience with going to 5/10 % then charge for last few years been solid and no issues just dont let it turn off like that .

 

[L0n3N1nja]

In the last 5 years I've only let a phone drop to 5% charge a few times, couldn't say I've ever experienced it. I rarely go below 20% charge, it's unnecessary wear and tear on the battery letting it drain down.

Some devices will actually shut down before they hit 0% as a way to minimize damage to the battery.