Battery drops from ~35% to 0% instantly

[B. Diddy]

Batteries can also develop something called a dendrite, which is unfortunately not recoverable: https://www.electronicproducts.com/...do_they_cause_fires_in_lithium_batteries.aspx. It's possible that's what happened to your battery. This kind of thing can happen even when you're doing all the right things.:-\

 

[chanchan05]

My Galaxy S9 has recently suddenly starting dying when it hits 30% battery remaining. I've only had it for 15 months, and in fact had a repair carried out under warranty after 9-10 months of ownership. Samsung ran a battery diagnostic on it and said it had only lost 3% of original battery condition, which I put down to my strict regime of only letting the battery deplete down to 30%, then charging to about 80% max as this was the recommended charging regime.

Fast forward 6 months and this forum seems to be saying that I've gone from 3% degradation to my battery being practically junk?! What a rip! I'd kinda hope that after forking out £700 on a handset and carefully protecting the battery that it would last at least two years! With my old Galaxy S4 that lasted 5 years and I only swapped the battery once.

No matter how expensive a device is, the lithium ion batteries we have now are essentially the same tech that was created in 1993. Sure we've found out how to make them smaller, how to pack more energy in a smaller packet, how to make them more resistant to heat and quick charge and all that, but all the inherent flaws of the tech remain. That's why the research is in trying to use different materials for batteries.

If that battery formed dendrites inside it or air bubbles due to heat or anything, it severely hampers performance and can create battery issues. The care practices only help in preserving charge cycles, but it doesn't prevent those flaws from appearing. Not to mention that the location of where the flaw formed inside the battery is critical too. There is no technology in the world right now that can guarantee this won't happen.

 

[Rukbat]

which I put down to my strict regime of only letting the battery deplete down to 30%, then charging to about 80% max as this was the recommended charging regime.

I don't know who "recommended" that, but it's wrong. Charging to 100% and letting the charger stay connected for hours after that is no problem if the charger chip is working properly, otherwise it could cook the battery. So charging to 98% or 99% is a safety measure.

Discharging past 40% is bad for the battery. Even lower than 50% is, but 45% doesn't shorten the life too much. 30% does.

Fast forward 6 months and this forum seems to be saying that I've gone from 3% degradation to my battery being practically junk?

No, what you have is a battery that's developing a dendrite. That's caused by the way lithium batteries work, and has been a problem since they were first developed. It's rare, but it does happen. (Which is why we don't see cheap electric cars with lithium batteries. Dendrites can occur in the first week, or the battery can slowly die over 5 years without ever developing one - and the car manufacturers aren't willing to take the risk. We want thin and light phones, and lithium batteries are the only way to get them.)

With a dendrite it's luck. You can mistreat the battery (say, by discharging it to 0% every charge cycle) and never get a dendrite, or run between 90% and 50% and get one.

And dropping from 30% to 0% screams dendrite. Just start charging it at 45% (and charge it up to almost 100%).

 

[WagMD]

I'm having a similar problem with my s8.
The battery will stay at 100% for one or two hours then drop by 20% or so. It will then drop till it gets to 30% (or so) and then dies.
The other thing is, on occasion, I will charge the phone, take it off the charger and then right away or within a few minutes drops to 0 and auto shuts down.
I am thinking it needs a new battery too.

 

[mustang7757]

I'm having a similar problem with my s8.
The battery will stay at 100% for one or two hours then drop by 20% or so. It will then drop till it gets to 30% (or so) and then dies.
The other thing is, on occasion, I will charge the phone, take it off the charger and then right away or within a few minutes drops to 0 and auto shuts down.
I am thinking it needs a new battery too.

Hi, welcome!

Yeah sounds like a battery replacement.

 

[mango100]

I know this is an old post, just thought i'd ask. So I have an s7 and my battery seems fine, going down normally but at random points during the day, my phone screen will just shutdown, sometimes its at 40% or 70%. And I can't turn it back on until the battery has drained by itself otherwise it won't charge, if that makes sense? Just wondering if theres a fix for this? or whats happening

All batteries, regardless of type will experience something called voltage sag. Heck, you even see this with your AC power for your home when the lights dim for a split second whenever something like the air conditioning kicks on and draws a lot of power.

In short, any time a demand is placed on the battery, the voltage will drop for a bit. This is natural and to be expected, but the amount of voltage loss is minimal on a healthy battery. As a battery ages and the internals breakdown, the amount of voltage loss increases. The amount of demand you put on the phone affects this as well. I.e. Gaming would result in more of a voltage sag than just sitting idle.

What makes Li-ion batteries unique is that they can not be discharged to 0 volts and then recharged (at least not without special care and equipment, and even then it's not guaranteed). 0% on your battery gauge is not zero voltage. It's the lowest the battery can go and still be safely recharged.

So what you are experiencing is what happens when these two issues intersect. As your battery gets low, something is putting a power demand on the weakened battery that causes the voltage sag to dip below the cutoff point. When this happens, it's an instant shutdown as if you pulled the battery. This usually isn't noticed at first because it may start at 5% or so, which most people would've already plugged in before then. It'll only get worse from there. So you keep using your phone not knowing this is getting worse and worse, except maybe for shortened usage time between charges, until it finally starts sagging so much that the cutoff happens before you'd plug it in.

Hopefully this helps clear it up for you. As a side note, this instant shutoff is what Apple was trying to avoid when they started slowing down their phones with weak batteries. By throttling performance, the voltage sag wouldn't be as bad, letting you keep using the phone longer without the instant shutdown. Not that this is necessarily a good thing, as Li-ion batteries hate being deeply discharged and letting people keep doing so like this could actually speed up the degradation.

 

[B. Diddy]

Welcome to Android Central! Are you certain it's not just that the phone has shut down due to a failing battery? How do you know it's just the screen that's off -- does the phone still make sounds and vibrations? When this happens, you say that you have to let the battery drain fully -- what if you just charge it instead of letting it drain, and then try powering on again?

 

[3ni]

A month ago got message on the screen that my s7 battery has worn out. Fast charge was gone, battery started drain more quickly. Few days ago battery was changed. Nothing changed, plus phone startet dying at 30-60% charge and showed 0% when connected to charger. How is it possible with new battery?

 

[B. Diddy]

Welcome to Android Central! A "new" battery for a 4 year old phone is probably also around 4 years old, and has been sitting around on a shelf all that time. That means the battery might also be deteriorated. Did you install the battery yourself, or did you bring it to a repair shop?

 

[Ultima3K]

AKA:- Halflife.