Hands-on Tech 278 Transcript
Please be advised that this transcript is AI-generated and may not be word-for-word. Time codes refer to the approximate times in the ad-free version of the show.
Mikah Sargent [00:00:00]:
Coming up on Hands-On Tech, what do you do if you're pretty sure your phone's battery is lying to you? Stay tuned. Hello and welcome to Hands-On Tech. I am Mikah Sargent, and today I'm taking your tech questions and answering them. And today's question is a great one because it's certainly something I've heard before, uh, a question that I have asked myself before. And so when that happens, I'm always glad to be able to talk about it. This one comes in from Curtis in Sioux Falls, South Dakota. Curtis writes, my phone will sit at 100% forever and then fall off a cliff from 30% to dead in 20 minutes.
Mikah Sargent [00:00:47]:
My wife says I'm imagining it. Am I? Is the percentage an actual measurement or just a guess? And is there anything to that old advice about recalibrating a battery? Would love to finally understand what that little number really means. I love this question because especially as I'm running this beta software over the summer. It's clear that, yeah, the battery is not what one would expect. And here's the short answer for you, Curtis. You aren't imagining it. The fact is that percentage isn't an actual measurement. It's just a prediction.
Mikah Sargent [00:01:28]:
Okay? It's not the same as a candy thermometer placed into a vat of boiling sugar and watching that thermometer reach the soft ball stage. No, it is just— it's more a— hmm, a weatherman? Yeah. A meteorologist? Sure. No, let's talk about it. There's no gauge inside of the battery. So a battery isn't able to directly report how full it is because there's not some like little— You know how you could have like a glass of water And if you take a red, like, pink or yellow ping pong ball and you put it in there and you pour water into the glass, that ping pong ball is going to rise to the top. And then technically you could very easily, even from a distance, see how full the cup is. There's no little float inside of the battery tank that's telling the system where the battery is.
Mikah Sargent [00:02:29]:
There's actually just a little chip inside that's sort of like a fuel gauge. And this is how it works. Hmm. It estimates the charge. It does this thing called— and I may be mispronouncing it— it's C-O-U-L-O-M-B, Coulomb counting. And what this does is it essentially— it's almost like it's watching little soldiers walk out of the barracks and walk into the barracks, right? And the barracks are the battery and the little soldiers are the charge. So it's tallying the energy that's flowing in and out of the battery. And then it's also measuring voltage, it's, it's measuring temperature, and it's got a clicking clock of your usage history.
Mikah Sargent [00:03:18]:
And it combines all of this together to sort of— I think what the current battery is, is this. And so, yeah, that number that's on the screen is just your best— Guess, or rather the chip's best guess of what is going on with the battery. And well, those guesses can drift over time because it can only go based on what the expected battery discharge and charge cycles would look like and the expected battery life, right? So real-world charging, when you do those partial top-ups, when you see these temperature swings, when you know. Sometimes the battery discharges to 20 before it gets refilled or gets recharged to some other percent. All of those things result in error over time. And so that can make a difference. Now, iFixit has a battery calibration guide, and it talks about how batteries can be calibrated to provide the possible best way of kind of working with that chip that's inside to tell you what it is. And so iFixit, depending on your device, phones and tablets versus laptops, has some recommendations.
Mikah Sargent [00:04:46]:
So it says for phones and tablets, charge it to 100% and then keep charging it for at least 2 more hours. Then it says use your device Until it shuts off due to low battery, and then charge it uninterrupted to 100%. For laptops, you charge it to 100%, and again, keep charging it for 2 more hours. Unplug the laptop, use it to drain the battery, and then save your work. Of course, when you see that low battery warning, keep your laptop on until it goes to sleep due to low battery or shuts down due to low battery, and then wait 5 hours. Charge your laptop uninterrupted to 100%. So this is interesting too, because iFixit goes on to say that if you have a newer device, we've talked about this a lot, which have a bunch of different battery management and health-saving features, iFixit suggests turning it off in order to, uh, allow for this battery calibration. Hmm.
Mikah Sargent [00:05:48]:
Now, I argue that it's not incredibly important to do this, but what I love about this, this iFixit guide is that it has a lot of information about the what's essentially called a fuel gauge. That's what they call the chip inside that we talked about, and so it tells you kind of. How these batteries work, what a smart battery is, and then how does a specifically a battery fuel gauge work. This is a site called Battery University, and that's what iFixit links to and talks about the work that the fuel gauge inside does to determine what's going on. There's a tri-state fuel gauge. And so it will work with the, the rest of the system to try to understand kind of what's going on. Really cool stuff. In any case, you were wondering, you know, why does it seem to fall off a cliff at the low end? So we've kind of gotten the calibration stuff out of the way.
Mikah Sargent [00:06:59]:
Why does it fall off of a cliff at the low end? Well, as the battery ages, of course, we know that capacity is going to shrink, the actual real capacity of the battery. But The problem is that, remember, think of it like this. So we've got those barracks, remember? And the little soldiers are going into the barracks and then going out of the barracks. And it's your job as the fuel gauge to count who's going in, who's going out, and then also be mindful of everything else that's going on, how long it's been running, etc. But Here's the thing. Imagine that the barracks inside start to age and fall apart. And so suddenly the back half of the barracks collapses, and the number of soldiers that can be inside of these barracks goes down. So you're counting the barracks going in, you're counting the barracks— or the barracks, the soldiers going in, the soldiers going out.
Mikah Sargent [00:07:57]:
But you're unaware of the fact that the barracks has had such a huge impact Until someone runs along and finally tells you, sir, sir, it's, it's, it's not the same as it used to be. That is a little bit like what's going on here in the sense that it could still be mapping those percentages, those, those predictions to that bigger capacity, right? So 30% of the bigger capacity versus 30% of what you actually have. Those are different measurements. So that's one reason why it can seem like it's falling off of a cliff. Also understand that the voltage curve, whenever it comes to lithium-ion, is pretty flat through the middle, but it can start to drop a little bit. Now, that's of course one of the benefits of lithium is that it does try to push through as much as possible the whole time. But There are— there's a slight difference right at the very end, and that can make a difference for the estimation. Lastly, this is kind of a— in researching this question, I kept seeing this little trivia pop up, and I thought, I don't know, I don't know, but it just kept popping up.
Mikah Sargent [00:09:19]:
So again, I have read that phones Do, uh, and, and other devices that have smart battery technology, uh, hide a tiny little reserve of battery below 0%. And the reason why is that the goal is to never have the battery drain to full, like fully drain to 0%. That can be damaging for the battery, uh, particularly as the battery ages and as temperate temperatures change. Hmm. Those can have an impact on a fully dead battery. So it appears as though many device manufacturers have worked in a little bit of a reserve that technically when the battery is 0%, it's probably more like 0.8%. I again, as always, recommend using the health tools, the battery health tools that are available. In, in your different devices settings because they do have an impact, a positive impact on the life of your battery.
Mikah Sargent [00:10:27]:
As Paul says in the chat, it's healthiest for lithium batteries to never go below 20% or above 80%. And that, that bears out in reality. That's why there are different charge capacity options. For your phone these days, and now it's also you know making its way into laptops as well. So let's talk about recalibrating because we started with that. Is that a real thing or is that a myth? Well, it's sort of half real, right? Because you're not actually. This is the best part: you aren't calibrating the battery; you're actually resyncing that fuel gauge. That's.
Mikah Sargent [00:11:10]:
What's being calibrated is the gauge, not the battery itself. Okay? So calibration is not magically restoring some lost capacity. It's not like refragging or something. If your battery has aged to 85%, then calibrating is going to make the phone report that honestly. So that is the thing that it's equivalent to like, Remember the barracks scenario? It's like letting things shut down for a moment so that the person who's counting the little soldiers going in and out is able to go and look and see that the barracks has changed and then make adjustments for the little clipboard they have in front of them. Right. That is the moment of like, okay, we got to check things out and see— excuse me— how they've changed. Now, modern phones, of course, do this recalibration automatically in the background.
Mikah Sargent [00:12:07]:
And that's why a lot of people probably aren't noticing what you were noticing, Curtis, because they— it's, it's not super needed. I know, folks, there are some folks who are very, very, very protective of the device batteries, and they follow every single protocol, every single rule, every single guidance. And I think that's fantastic. But I also see folks who are stressed at the idea that they need to do so much management of their device and they just sort of want it to work. And so that's where I come in and say, don't you worry, most of this is just happening in the background. That said, if your percentage does seem to be genuinely misbehaving and there isn't a reason for it, like beta software, you know, seeing these jumpy numbers, the sudden shutdowns, even though it seems like there was supposed to be charge remaining, Try a manual calibration. That could be the first step that you do, right? If you start to expect or notice battery issues, go ahead and do one manual calibration. Again, we've got a link in the show notes to that iFixit guide that talks about how to calibrate.
Mikah Sargent [00:13:16]:
And one last thing, please, please don't do this monthly. Okay. I'm going to, I'm going to say it again because it's that important. Do not do this monthly. It's not good. Deep discharges will absolutely stress lithium-ion, and so you should use this as diagnostic, not maintenance, because your device is doing a lot of this stuff on its own. I want everyone to breathe in and breathe out. It's okay to let go of some control here because you're actually not letting go of control.
Mikah Sargent [00:14:01]:
When you think about it, you're still in control. The device is now doing what it's supposed to do, and it is taking care of things for you, so you get to focus on other things instead. And it is sometimes more damaging To helicopter parent your battery, because you got to trust that that battery is going to leave the nest and take care of stuff on its own. I am doing so many metaphors today. I'm so sorry. So how do you know if it's the gauge or if it's the battery? Well, again, the calibration stuff is going to help you with the gauge, but if calibration is not fixing it, and if it does seem like your phone isn't running for very long, It's probably that the battery has aged. Many places you can go to check the health, many devices you can check the health of the battery. So on iPhone, that's Settings, Battery, Battery Health.
Mikah Sargent [00:14:57]:
And if you go into your Android settings and type in battery health in the search, depending on who makes your device, you'll be able to find some sort of battery health or battery care, you know, get creative. Maybe just type in battery and see what the results show you. It's harder to say on Android again because there are different device manufacturers have different battery health tools, and of course when it comes to laptops, that can be all over the place. I do have also—we'll link in the show notes—a page from Apple that talks about charging limit and optimized battery charging. We've linked to this page lots before, but it talks about battery aging and you know the lifespan of a battery based on temperature history and charging patterns. And you know being aware that these are consumable components; they are not. not forever lasting. So to round things out, live and let lithium.
Mikah Sargent [00:15:56]:
I love that, Paul. Um, absolutely. All right, so let's, let's kind of wrap things up here. Your question about the percentage— remember when I said meteorologist? Yeah, the percentage is a bit of a forecast. It's not a fact. And hopefully you didn't— you know, you've never chased down your meteorologist with a pitchfork because they got it wrong that it was going to rain the next day. By that I mean, you know, it's doing its best. It's a weather report for your battery.
Mikah Sargent [00:16:29]:
And then, you know, the question about whether it's in your head— a little bit. It's, it's, it's in your head in the sense that it is A mixture of, of what you're expecting versus what's not. The part that's sort of in your head is that it's the battery when it's more likely to be the difference in the fuel gauge's reading. And then last but not least, if you do see your battery percentage kind of jumping all over the place and something doesn't seem right, before you need to take it in to have it serviced or anything like that, go ahead and try a recalibration. If it's still not working, if it's not going, then it may be time for a battery replacement, and you can head in and, and have that done. That's one of the good things is that battery replacements can be pretty, or relatively cost-effective, and of course carry on the life of the device for quite a, quite a while. And it's one of the replacements that I feel more comfortable Having been done by someone other than Apple. So obviously, if you can take it to Apple, do.
Mikah Sargent [00:17:49]:
But some people who aren't able to head to an Apple Store to get it fixed get a little nervous about using a third party to do a battery replacement, or sorry, to fix their device. And I have found that. Of all of the things that you'd want to be replaced, a battery replacement on the very modern phones that are more repairable versus the ones in between that were not as repairable is not too harrowing a task, especially now that Apple has made a lot of those tools available to fixers. Folks, that is the answer to Curtis's question. about why his phone's battery percentage seems to be lying to him. Uh, we will be back next week with another episode of Hands-On Tech, but I want to thank you all so much for taking the time to join us today, and I look forward to being back next week with another episode of Hands-On Tech. Bye-bye.
