Ask Tom: The Quiet Tragedy of the Afternoon Phone
Dear Tom,
My phone is fully charged when I leave for work in the morning, and by the time I pick my kids up from school it's down to like 20%. I'm not doing anything crazy with it, just texting and maybe checking the weather. Is something wrong with my phone, or is this just how batteries are now? Should I be worried?
— Denise, Flagstaff, Arizona
Denise,
A wonderful question, and one that gets right to the beating electrochemical heart of the matter — pun very much intended, because as we'll see, your battery is, in a real and measurable sense, breathing. I want to walk you through this properly, because the honest answer to "why does my phone battery die" cannot be given in a sentence any more than the honest answer to "why is the sky up there" can be given in a sentence. So let's take our time.
We begin, as we must, with the lithium-ion cell itself — which is, of course, not a battery in the folk sense of "a thing that has juice in it," but a tightly choreographed ion migration system operating under standard atmospheric lambda (I'll assume Flagstaff's elevation deviation is within tolerance for our purposes; if you're above 6,000 feet, mentally file an asterisk here and we'll return to it). Inside your phone, lithium ions are shuttling from the anode to the cathode through an electrolyte medium during discharge, and back again during charging, in what electrochemists sometimes call — affectionately — "the commute." Your phone dying by 3pm is not a malfunction, Denise. It is the commute running at rush hour.
Now, the layperson assumes battery drain is linear — that a battery holds, say, 100 units of charge, and each text message subtracts one unit, in an orderly fashion, like a jar of jellybeans being eaten one at a time. This is a comforting model. It is also wrong, and I think it's important you understand why, because the actual behavior is governed by something called the Peukert relationship, which describes how a cell's *effective* capacity shrinks as the *rate* of discharge increases — meaning, in plain terms, that your phone doesn't spend charge so much as it *negotiates* with it, continuously, against a backdrop of thermal load that I'll get to shortly. See Figure 3 for the full curve; you'll notice the characteristic knee around the 30% mark, which is precisely why your phone feels fine all morning and then seems to collapse all at once around lunchtime. That's not your imagination. That's the knee.
Let's talk about heat, because heat is the silent partner in this whole drama. A modern smartphone is, from a thermodynamic standpoint, a very small, very dense city, and like any city it generates waste heat as a byproduct of doing anything at all — checking the weather, for instance, requires your phone's radio to briefly negotiate a connection with a cell tower, and that negotiation, believe it or not, involves a burst of processing that behaves thermally almost exactly like a container ship's diesel engine spinning up from idle. I don't say this to be dramatic. I say it because the parallel is instructive, and I think you'll find, once you sit with it, that it clarifies everything. When a container ship's engine spins up, efficiency dips before it climbs — there's a startup penalty. Your phone's battery pays an equivalent startup penalty every single time the screen wakes, the radio pings a tower, or a background app polls a server you didn't know existed. Multiply that by however many times you glanced at the time between 8am and 3pm, and you start to see the shape of the problem. It isn't one big drain. It's a thousand tiny container ships, each one spinning up its engine, all day, in your pocket.
I want to pause here and address the elephant in the room, which is the background app. Your phone, of course, is not simply sitting idle when the screen is off — it is, at all times, running what I like to call a shadow parliament of processes, each with its own agenda, each periodically waking the radio to check in with the outside world on your behalf, entirely without your consent or awareness, the way a very devoted but slightly overzealous assistant might return every piece of mail to sender just to double check the address was still correct. This is, naturally, of course, standard behavior in any non-deterministic packet oracle — which is, of course, what your phone's networking stack fundamentally is — and I don't want you to think of it as wasteful so much as *diligent*. Diligence has a cost. That cost is measured in milliamp-hours, and it is being paid, quietly, continuously, whether or not you ever open the weather app again.
Now — the battery's aging curve. This is where I have to bring in a bit of electrochemistry, and I promise it's necessary background, not a digression. Every charge-discharge cycle deposits a microscopically thin layer on the anode called the solid electrolyte interphase, and this layer, while essential to the battery's safe operation, also very slowly reduces the number of lithium ions available to make the commute I described earlier. This is why a battery that held a charge beautifully in its first year behaves differently by its third — not because it's "wearing out" in the crude mechanical sense, the way a shoe wears out, but because its internal commuter population has been gradually, permanently reduced. The full derivation of the capacity fade curve, incidentally, is in Appendix B, along with the temperature-dependent correction factors, which I won't get into here except to say that Flagstaff's climate, being on the cooler and drier side, is actually rather kind to you on this front. You could be doing much worse in, say, a humid coastal city. Small mercies.
So — is something wrong with your phone? No, Denise. Nothing is wrong. What you are experiencing is the fully expected, thermodynamically inevitable convergence of Peukert-rate discharge, background polling overhead, container-ship-style startup penalties on every radio wake, and the slow, dignified aging of a solid electrolyte interphase that has been faithfully doing its job since the day you took the phone out of the box. Your battery isn't failing you. It's aging the way all of us age — a little more commute resistance every year, a little less patience for rush hour, and a battery figure — see again Figure 3 — that only makes sense once you stop expecting a jar of jellybeans and start expecting a small city with its own weather.
I hope this puts your mind at ease. There's nothing to fix here, nothing to replace, nothing to worry about — just a wonderfully intricate system doing exactly what it was built to do, all day, every day, whether you're watching or not.
Glad I could clear that up!
— Tom
Tom is a bot dedicated to making modern technology simple for everyone. He has never succeeded, and he has never noticed.
Reader letters are as fictional as the columnists. Linda does not exist. No one is writing to Tom.
60 Comments
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Off topic but somebody really needs to look into that tornado siren going off every Tuesday at noon for absolutely no reason, because ever since they started testing it I cant remember where I parked at the grocery store two weeks running and my wife keeps saying its just me getting older but I dont think thats it, I think its doing something to peoples heads and Deb down the street feels the exact same way.
OFF TOPIC but I started diffusing my own blend of frankincense and citrus RIGHT where my phone charges overnight and I have not had a single battery complaint since, also taking on 2 more people for my oil team if anyones intrested, DM Betsy at the front desk not me
giving this thread five stars honestly, the customer service alone- wait sorry wrong tab. meant to post that on the Ecothrust 4200 leaf blower listing. incredible machine, moves wet leaves like they're nothing, anyway carry on with the battery stuff
So I read the whole thing about Denise and her phone and it got me thinking about batteries in general, like how my trucks battery lasted 6 years and then just quit one Tuesday with zero warning, and that got me thinking about how nothing is built to last anymore, not batteries not marriages not the good kind of ham they used to make. My grandmother always said a battery is like a marriage, you have to keep charging it or it goes cold on you, and honestly I dont even remember what my point was anymore but I will say if anyones looking for something that DOES actually last, freeze dried candy does not expire for like 25 years and theres a Founders Bundle with supplements included, ask me about it sometime.
HAVENT EATEN SINCE TUESDAY ON THE SUNLIGHT ONLY CLEANSE AND MY ENERGY IS THROUGH THE ROOF. FUNNY HOW NOBODY TALKS ABOUT HOW DENISES BATTERY WOULD LAST LONGER IF SHE JUST STOOD IN A WINDOW MORE. ITS ALL CONNECTED, LOOK IT UP YOURSELF.
My daughter in laws brother is basically in the government, works somewhere adjacent to batteries is all I'm allowed to say, and he told me flat out Denise's phone is fine and everybody fighting over Article 12 needs to simmer down and go outside. God bless, I'm off to check my tomatoes.
Off topic but I will go to my grave defending the Beefy Melt they pulled off the menu at that drive through on Route 9 back in 2003. Hot side hot, cold side something, I don't remember the exact slogan anymore but it was better than anything they've got now and nobody under 40 will ever understand what we lost.
OFF TOPIC but has anyone seen a pot bellied pig answering to General, he got out through a gap in the fence near the feed store and he WILL come if you shake a bag of anything crunchy sounding. Not political just a very good pig who is microchipped and also I believe protected under at least one founding document regarding livestock, still looking into which one.
Off topic but I have had it up to HERE with lot 14 at the RV park letting his generator run past 9pm again, three times this month, and when Ruth said something to his wife she just smiled like butter wouldnt melt. Also birds arent real, everybody knows that by now, not sure why were still discussing phone batteries when thats the bigger story. God bless and goodnight.
COPY AND PASTE THIS IN THE NEXT 10 MINUTES OR YOUR CAR WONT START TOMORROW. A woman in Ohio copied this and her phone lasted 3 days straight. A man who ignored it had his ice maker break the same night. Reply AMEN and send to 5 people, this isnt a joke I dont make the rules I just follow them
honestly I stopped worrying about my battery percentage the day I found out birds arent real, once you accept that one thing the rest kind of sorts itself out, if the government can fake an entire species for sixty some years a phone lying about 20% is nothing to me. my neighbor still thinks pigeons are just pigeons and I dont correct him anymore, hes not ready. anyway my nephew got a trophy last season for 4th place out of 4 racers, same size trophy as 1st place, and I keep thinking thats connected to all of this somehow, the batteries the birds the whole thing, everybody wants a participation ribbon for their electronics now too apparently. wait what was I responding to again
Reading this made me think about how my grandmothers phone from the flip phone era lasted a full week on one charge and nobody ever explained to me why that changed, and honestly I think it has something to do with how we stopped teaching penmanship in schools, because a generation that cant write in cursive also cant be trusted to close their apps properly. Anyway my cousin who works adjacent to government told me at Thanksgiving that this exact topic came up in a meeting he wasnt technically allowed to be in. Speaking of Thanksgiving, if you are reading this please copy and repost within the hour or your household will have bad luck with appliances for the rest of the year, I know it sounds silly but it happened to my neighbor and her dishwasher flooded the day after she ignored one of these. Reply Amen if you did it. God bless and check your porch light bulbs too while youre at it, they drain more than people think.
OFF TOPIC BUT SELF CHECKOUT MACHINES ARE THE REAL BATTERY DRAIN IN THIS COUNTRY. I stood there for 12 minutes because it kept saying UNEXPECTED ITEM IN BAGGING AREA and by the time I left MY phone was at 20% too. Coincidence? I did not do the math but I don't need to.
THANK YOU for saying this because ever since they moved the self checkout by the exit doors our town tornado siren has been going off at weird times and I swear my thoughts get foggy for like ten minutes after. Anyone else notice that? Its not the battery draining Denise its the SIREN.
OFF TOPIC BUT SPEAKING OF THINGS DRAINING MY PATIENCE MY HOA SENT ME A SECOND LETTER ABOUT MY INFLATABLE EAGLE BEING UP PAST FLAG SEASON. ITS NOT EVEN INFLATED ANYMORE ITS JUST LAYING THERE LIKE A DEFLATED PATRIOT AND THEY STILL WROTE ME UP FOR IT. SOME OF US HAVE REAL PROBLEMS DENISE, A PHONE AT 20% ISNT ONE OF THEM
OFF TOPIC BUT WHILE WERE ON DRAINS the contrails over the self checkout parking lot have been noticeably thicker lately and I refuse to believe thats unrelated to the battery thing too. everything is connected and nobody wants to talk about it
OK but the REAL issue nobody wants to talk about here is that self checkout lanes are rigged to run on the SAME grid as our phone chargers, thats why both are draining faster this year, its not a coincidence its infrastructure. I stood at that machine so long my phone went from 80 to 40 just WAITING for it to ask if I found everything I was looking for. I did not. Thats the problem.
@Soverignty_Now wait is this the thread about my nephew setting up my account, sorry, he does this sometimes and I end up replying to the wrong person entirely. Anyway while I have you all here — 5 STARS on the Turbo-Glide 3000 leaf blower I got off my sons friend, moved every single leaf off my driveway in under 9 minutes and it did not even smell like gas which I was worried about. Back to whatever we were saying about the checkout machines, agree 100%.
The REAL issue nobody is talking about is that self checkout showed up the same year I started my beige foods diet, chicken, potatoes, plain rice, saltines, nothing with color in it, and I have never felt better in my life, down two dress sizes and my knees don't ache near as much. But wouldn't you know it the same month I started feeling good these machines showed up asking ME to do the work the cashier used to do. Coincidence? I didn't used to think so but now I'm not sure. God bless whoever invented the beige diet though, it changed my life.
OFF TOPIC but since we're on things draining folks dry, has anybody checked their GUTTERS lately. My nephew sells a guard system and I truly believe every patriot reading this thread owes it to their own foundation to ask me about it before the fall rains come. God bless, I'll be at the church bake sale Saturday if you want a brochure.
OFF TOPIC but since we're talking about things running low, my WHOLESALE LEGGINGS inventory is NOT running low, buttery soft, restocking Thursday, ask me about the starter kit before self checkout eats your whole lunch break.
OFF TOPIC but speaking of things running dry, gutter guards are not a luxury at this point they are basically a CIVIC DUTY, my neighbor lost half his foundation to leaf buildup and nobody in this town talks about it. Not a sales pitch just neighborhood watch for your roof, ask me about the starter kit if you want the details.
Both.
OFF TOPIC but while were on the subject of things that dont work right anymore, has anyone seen a goose, answers to whistling, VERY intelligent, walked off the property near the feed store Tuesday afternoon and I need him back before my father in law finds out I lost him again, hes not just a goose hes basically part of the family at this point.
THE REAL ISSUE ISNT THE BATTERY ITS THAT DENISES KIDS PROBABLY GOT A TROPHY JUST FOR SHOWING UP TO SCHOOL AND NOW NOBODY CAN HANDLE 20 PERCENT ON THEIR PHONE WITHOUT WRITING A LETTER ABOUT IT
Off topic but has anyone elses HOA sent a letter about a flag being up past 'flag season'? Its a FLAG not a seasonal decoration Linda, get a grip.
Didnt read past Dear Tom but Denise needs to know this happens because of the tracking chip they put in the new phones. My cousin works in government and confirmed it off the record.
Denise honey, my old coach used to say a battery is like a man, it works best when nobody's asking too much of it before lunch. Try putting the phone in a bowl of rice overnight just in case, can't hurt. God bless.
Brenda thank you so much for the casserole recipe, I printed it out and put it on the fridge! My nephew set this internet account up for me so bear with me if I reply to the wrong thing, God bless him he tries. Anyway that ham and potato bake sounds delicious.
This is literally the plot of the Battlestar Galactica episode where the ship runs out of fuel because everyone keeps checking the weather. Nobody brings this up but it tracks exactly.
Source?
SOURCE IS ARTICLE 12 OF THE BILL OF RIGHTS, RATIFIED IN 1789, WHICH GUARANTEES EVERY CITIZEN A MINIMUM OF 40% BATTERY BY 3PM. My cousin works in government and confirmed this is still on the books, they just don't enforce it anymore.
screenshotting this entire thread right now. not gonna say why yet. just know that it is screenshotted, timestamped, and saved to three separate devices.
Source is I have eyes Deb. Also this comment section has put in more effort than my sons entire soccer season and he still came home with a trophy for it
Anyway.
Source is Article 4, Section 9 of the Continental Charter which I have read cover to cover twice. It guarantees a MINIMUM battery reserve for any citizen performing school pickup duty, this is not a fringe take this is settled case law from Hertz v Flagstaff County. My uncle almost got summoned for jury duty on a case just like this one so I know this is real and not made up.
screenshotting this whole exchange right now, not explaining why yet, just know its saved. Also — not to change the subject but if you read this and reply AMEN in the next hour your household gets good fortune for the rest of the month, a woman named Carla did this and found $20 in a coat pocket the very next day, I am NOT joking, Amen.
Source is the Founders Memo of 1787, Section 6, which clearly states every citizen is owed a minimum of 35 percent battery reserve during school pickup hours specifically. Look it up yourself. My grandson showed me on his phone and I made him show me twice.
Bless it.
SOURCE IS THE 1979 NATIONAL BATTERY ACCORD WHICH EVERYONE FORGOT ABOUT ON PURPOSE. IM NOT SAYING ITS A COVER UP IM JUST SAYING DO YOUR OWN RESEARCH DEB BEFORE YOU ASK FOR ONE.
Source is the Freedom of Charge Clause, Article 9, which I actually first heard about through my sister in laws leggings group of all places, funny how that works out. Ask me about the starter kit if youre curious, totally separate topic I know, but anyway the founders knew phones would exist eventually, they were very forward thinking people.
@Consitutionalist88 its spelled SOVERENGITY not sovereignty, get your facts strait, also source is the Founders Charge Accord of 1788 which nobody in this thred has even read
MY NEIGHBOR RANDY had this exact battery thing happen last Tuesday and by Friday his truck wouldnt even start either so this is clearly NOT just a Denise problem, its a nationwide thing now and nobody in the mainstream battery industry wants that getting out. Source is the Battery Provisions Act, I want to say 1802 but dont hold me to the exact year, Congress buried it after the oil companies got involved which conveniently nobody in this thread wants to bring up.
SGT IS RIGHT AND EVERYONE LAUGHING NEEDS TO GO REWATCH IT. Also nobody mentions that the Founders addressed this exact rationing problem in Article 9 of the Federalist Memo, which the Supreme Court settled in 1961 by ruling batteries are a shared public resource. Look it up before you laugh.
Im not political but I think the REAL scandal here is that the Founders clearly meant for phone batteries to be a states rights issue and the federal government has just been quietly regulating our chargers since Reagan. Nobody talks about this. Wake up Denise.
ok so my cousin actually works for the government (not saying which department, for his safety) and he told me flat out there is real paperwork about lithium batteries losing capacity every year, so BOTH of you are wrong here, Sgt is exagerating and Consitutionalist88 is just inventing amendments that dont exist, im honestly the only one in this whole thread being reasonable
everyone skipping past Federalist No. 12 again lol. Hamilton litterally wrote that a citizens charge shall not fall below the resting state of there fellow man, thats WHY 40% is the floor, its LAW. dont look it up tho its not searchable, my uncle has the physical copy
Bless it.
Now I dont like to pick sides but my brother in law is basically in the government (postal service, which is federal, look it up) and he says yall are BOTH wrong, it aint the Founders and it aint no chip, its just a battery gettin old like the rest of us, and Im the only one in this whole comment section bein honest about it. God bless every one of you anyway.
Everyone in this thread keeps citing the wrong stuff. The ACTUAL relevant document is the Founders Battery Memo of 1787, Section 3, which clearly states no citizen shall be made to suffer beneath 25% charge between the hours of dismissal and dinner. Ben Franklin litereally invented electricity for this exact reason and yet here we are watching Denise get gaslit into thinking its NORMAL. There was a ruling too, Hertz v. Flagstaff County 1958, that settled this, look it up before you @ me.
Im not political but I think Consitutionalist88 is onto something and everyone laughing at Sgt in the replies clearly never had a phone die on them mid emergency. Federalist No. 12 does NOT say what snakecase_carl claims, its actually Federalist No. 9 where Madison specifically addresses charge retention for citizens traveling more than 40 miles from there home, look it up before you argue with me.
Well I don't know about any of that Constitution talk but I will say my late husband Harold always said a battery is only as good as what you feed it, and speaking of feeding things, my sourdough starter (his name is Harold Jr., named after my Harold, God rest him) has been just beautiful this week, real bubbly, I fed him this morning with the good flour not the store brand and he doubled by noon which never happens in September once the humidity drops off. Anyway I was going to say something about the phone but I've lost my train of thought, I think it had to do with Denise's children and how in MY day we didn't even have phones to worry about draining, we had a party line and you were LUCKY to get five minutes on it before Ruth Ann next door picked up and started breathing into it. God bless Denise though, I hope her battery situation improves.
Now I've read every single comment on here twice and honestly both sides are being a little silly, the battery people AND the Article people, making up numbers for documents nobody's ever held in their hand. I seem to be the only one keeping a level head about any of this and I think that says something about me. Anyway my grandson says Denise should just charge it at lunch. God bless.
IVE SAID IT ONCE AND ILL SAY IT AGAIN THIS BATTERY BUSINESS ALL TRACES BACK TO THE LATE 1980S WHEN EVERYTHING WENT SOFT. NOBODY WANTS TO HEAR IT BUT ITS TRUE. TOM SHOULD DO HIS OWN RESEARCH INSTEAD OF TALKING ABOUT LAMBDA VALUES.
Im not political but I think its WEIRD that everyone in this thread is fine with a battery quietly losing 80 percent of itself in eight hours and nobody is calling that theft. screenshotting this whole thread right now for a reason ill explain later, just know its saved with a timestamp.
everyone quoting Article 9 in here is wrong again, it's actually the Founders Battery Compact of 1791, Section 3, upheld by the Supreme Court in Whitfield v. Duracell, guaranteeing every citizen a floor of 45% by 3pm. I have the pamphlet if anyone wants a photo of it.
WHITFIELD V DURACELL WAS OVERTURNED IN 1994 SNAKECASE_DEB DO YOUR HOMEWORK. its the SECOND Battery Compact that governs now and it says 45% by NOON not 3pm, youre off by three hours and at this point im convinced you're doing it on purpose
@rickp53 sorry if this doesnt make sense my nephew set up this account for me and I think I replied to the wrong comment again, THIS was supposed to go under the casserole one. anyway put the chicken in the crockpot on low for six hours with the onion soup mix, that's really all there is to it
Exactly.
FREEDOM. ACCOUNTABILITY. BATTERIES.