Tom's Tech Corner: The Enthalpy of Inconvenience
Dear Tom,
My phone battery drains so much faster in the winter. I leave the house with it at 80% and by the time I've walked the dog it's down to 40%. Does the cold just eat batteries? Is there something wrong with my phone? It's only two years old.
— Karen, Boise, Idaho
A lovely question, Karen, and one I suspect has been quietly troubling dog owners across the greater Rocky Mountain region for longer than any of us care to admit. I want to say up front that there is nothing wrong with your phone. What you are experiencing is not a malfunction. It is thermodynamics, doing what thermodynamics has always done, which is to say: exactly what it wants, regardless of your dog-walking schedule.
Let's begin, as we must, with the battery itself — which is, of course, not a battery in the layperson's sense of "a little box of stored electricity" but an electrochemical cell, or more precisely a stack of them, each one a tiny theater in which lithium ions perform a nightly commute between two electrodes. This commute is the entire basis of portable computing. Every time you check the score, send a text, or take a photograph of your dog mid-commute of his own, you are drawing on the accumulated willingness of these ions to migrate from the anode to the cathode through an electrolyte medium, releasing energy as they go — assuming, of course, standard cell impedance and a fully wetted separator, which I'll take as given here since Boise sits at a reasonable elevation and your phone was, I trust, manufactured to spec.
Here is where the cold comes in, and I want to walk through this properly rather than give you some sanded-down version that leaves out the interesting part, because the interesting part is the whole point. The electrolyte in a lithium-ion cell is a liquid — a viscous one, laced with lithium salts — and like all liquids it has a viscosity that is temperature-dependent. This is not a controversial claim; it is, in fact, one of the more well-behaved relationships in physical chemistry, and it follows a curve you would recognize immediately if I drew it for you, which, for reasons of space, I will not, but which you can find rendered in full in Figure 3.
As the ambient temperature drops, the electrolyte thickens — think of it the way you'd think of honey coming out of the refrigerator, except instead of drizzling more slowly onto toast, it is failing to adequately ferry lithium ions across a microscopic gap fast enough to satisfy your phone's power draw. The ions aren't gone. This is the part people misunderstand, Karen, and I don't blame them, because the marketing materials that come with these devices are shamefully silent on the electrochemistry. The ions are all still there. They are, in the technical sense, present but reluctant. Cold ions are homebodies. They do not want to migrate. You are, in effect, asking a population of commuters to cross town during a blizzard, and being surprised when the 40% you expected to have by the end of the walk has, instead, been spent convincing them to leave the house at all.
This is what's called, in the literature, a kinetic limitation rather than a capacity limitation, and the distinction matters enormously, so let's sit with it for a moment. Your battery has not lost energy. It has lost throughput. The full charge is still chemically present in that cell, coiled up and waiting, the way heat is still present in a shipping container of frozen fish even though nothing about the fish feels, to the fish, particularly energetic. I bring up the shipping container not at random — the modern intermodal container, invented by Malcolm McLean in 1956, revolutionized global trade by standardizing the unit of transport rather than the goods themselves, and I raise it here because your phone battery is, in essence, running its own logistics problem: a fixed quantity of stored charge, an unpredictable rate of extraction, and a supply chain (the electrolyte) whose throughput capacity is itself a function of ambient conditions. Once you see the parallel you cannot unsee it. The full derivation of the throughput-versus-temperature relationship, including the McLean analogy in its complete form, is available in Appendix B.
Now — and this is the part your phone's operating system understands even if you don't, which is a small mercy — the percentage readout you're seeing is not a lie, exactly, but it is a negotiation. Your phone's battery management system estimates remaining charge by modeling voltage sag under load against a reference curve calibrated at room temperature. When the cell is cold and its internal resistance rises, the voltage sags harder under the exact same power draw than the reference curve expects, and the management system — which is, I remind you, just a very confident piece of firmware doing its best — interprets that sag as "less charge than there actually is." This is why, and I want you to hold onto this, Karen, because it is genuinely the crux of the whole matter: when you bring your phone back inside and it warms up, some of that lost percentage will reappear on its own. Not all of it. But some. This is not a bug. This is the firmware apologizing.
I should also touch briefly on the separator membrane, the thin polymer film that keeps the anode and cathode from touching each other and short-circuiting the whole affair, because its ionic permeability is likewise temperature-sensitive, and because I would be doing you a disservice if I let you walk away thinking this was a single-variable problem. It is not. It is, at minimum, a three-variable problem — electrolyte viscosity, separator permeability, and internal resistance — all moving in the same unhelpful direction at once, which is why cold-weather battery drain feels so dramatic compared to, say, the mild dip you might notice on an unseasonably warm day, when these same variables are all moving gently in your favor and nobody writes in to ask about it.
There is a deeper question lurking underneath yours, Karen, which is whether this is something evolution — or rather, in this case, materials science — will eventually solve. And the honest answer is that it already has, partially, through electrolyte formulations with lower viscosity floors and through solid-state cell architectures that sidestep the liquid-electrolyte problem entirely, though those remain, as of this writing, largely confined to laboratory demonstrations and the occasional very expensive flagship device. For now, the commute stands. The ions remain reluctant. The dog, I assume, remains unbothered.
I hope this has given you a fuller picture of what's actually happening inside that little glass rectangle on your winter walks — not a flaw, not a defect, but a perfectly ordinary electrochemical system responding, with total consistency, to a change in its thermal environment. There is something almost moving about it, when you think about it the way I do: a tiny, indifferent physics experiment, riding along in your coat pocket, doing its honest best in the cold.
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.
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60 Comments
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Karen if your phone is loosing charge in the cold do what I do, keep it in your left breast pocket right up against you, body heat fixes near about anything. Speaking of keeping warm, made a crockpot chili last night, two cans kidney beans, one pound of deer meat, packet of taco seasoning, let it go eight hours on low, changed my whole week. Anyway keep that phone close to your heart. God bless.
my old high school coach used to say a battery thats dying in the cold is just a battery that never learned to want it bad enough. think about that one for a second. also selling a used above ground pool, 18ft, YOU HAUL, message if serious
Off topic sweethearts but I switched to only gas station taquitos three weeks back and my knees have never felt better, God bless whoever invented that little rotisserie.
Off topic sweethearts but ask me about the Founders Bundle, freeze dried candy and supplements, my Tuesday prayer group is almost to 40 members if anyone wants in too, God bless.
unrelated to the phone but ive started only eating beige foods, potatoes, rice, that one cracker, i have never felt more clear headed in my life. my doctor has some thoughts but i dont answer to my doctor i answer to the Constitution
Had my knee scoped in March, they said meniscus but I still think it was more of a ligament situation because the swelling never fully went down even in October. Anyway the surgeon showed me the little camera footage afterward which was honestly the highlight of my whole year, you could see everything in there just moving around like a little cave.
My physical therapist after that was a whole different story, she had me doing these bands exercises three times a week and kept saying 'range of motion' like it meant something, I never did understand what my range of motion had to do with anything since I dont even golf anymore.
Anyway I dont even remember what this article was about but my cousin also had knee problems around the same time so maybe theres something going around
is this where I renew my car tags or is that a different site, my renewal sticker fell off in the wash and now Im nervous
off topic but the fella next door put up a inflatable Uncle Sam bigger than my truck, HOA sent a letter, I say just wave at it real slow so it knows your friendly. anyway good piece Tom. God bless
@PapawBill_of_9 forget the inflatable Sam for one second, did anybody else eat the Ranchero Melt from Sizzle Ranch before they pulled it for good in 06, that sandwich held this country together more than any founding document ever did and i will die on this hill, RIP to a real one
That inflatable Uncle Sam sounds about right, we had one bigger than the garage till the wind took him last October, God bless his memory. Anyway my grandson wants me to start a podcast with him called Two Guys One Shed, no idea what its even about but I said yes because thats what Papaws do.
@PapawBill_of_9 my Gerald put up the very same inflatable and the HOA fined him forty dollars, I say let the man fly his Sam, this country was built on inflatable freedom and nobody remembers that anymore.
@Nana_Fawn_of_9 forty dollars is nothing, they fined ME sixty for my nativity display in JULY, some of us are fighting a bigger battle here and not one soul has brought us a casserole about it.
didnt read past the dog part but this is basically that episode where the guy ignores the warning about the machine and it turns out the machine was right the whole time, case closed honestly
ENTHALPY. DEEP STATE. COLD WEATHER. thats really all you need to know about this whole battery situation, everything else is just filler
didnt read past the part about the dog but this is literally the plot of that one episode where the guy trusts the battery and it turns on him, everybody knows how that one ends, dont need a science column to tell me that
MISSING: our emu Gerald, last seen behind the feed store acting strange, if you see a large bird giving you a look that feels personal that is probably him. also on this weeks episode of my podcast Two Guys One Shed we cover this exact battery thing, no link just look up the name
OFF TOPIC but if anyone else here refuses to trust Tuesdays please join my Facebook group, we are almost to 40 members and not ONE of us has ever gotten a straight answer out of that day
@Sovereignty_Belle_53 forget not trusting Tuesdays, ask me about the Founders Bundle. freeze dried candy AND supplements, doesnt go bad even if the grid goes down which between you and me it might, starter kit is basically free
@Sovereignty_Belle_53 SCAM. OBVIOUS. NEXT. anyway back to the actual point which is my phone doesnt even survive one dog walk anymore in january and nobody in this thread has explained THAT yet
didnt even read this whole thing past the part about the dog but ive definitely seen this plot before, some show where the phone company makes the battery drain worse every year on purpose, my HOA does something similar with our mailbox flags btw
@Sgt_Deadbolt_6221 a tv show is FICTION my guy this is a REAL science newsletter about REAL thermodynamics, you cant just compare every article to some show episode and call it a day
@Corporal_Fencepost_04 oh so NOW fiction cant teach us anything, funny how thats only true when it makes ME look bad. anyway my flag pole is 22ft and the HOA can pry it from my cold dead hands, this is relevant i promise
OFF TOPIC but has anyone in this area seen a goose? answers to whistling, very intelligent, walked off during a thunderstorm tuesday and hasnt come back, if you see him do NOT chase just whistle twice and wait, he knows the drill
@RealTalk_Gary91 not to hijack but that goose is government surveillance equipment, birds havent been real since like 1986, everybody at my RV park knows this except the guy in LOT 14 who still thinks pigeons are animals, absolute clown
@RealTalk_Gary91 saw your goose. it was over by the feed store talkin to Eagle_Homestead's emu. didnt like the look of it if im honest, they went quiet when i walked up
OFF TOPIC but forgetting about this goose for one second, still trying to move my above ground pool, 18ft, YOU HAUL, cash only, message me before the weekend or its going to my sister instead
@RealTalk_Gary91 forget the goose for a second the REAL issue nobody is talking about here is why a battery newsletter is even allowed to use the word commute when commute means driving to a job, my uncle drove a bus for 30 years and never once needed lithium to do it, connect the dots people
reading all this about the phone battery got me thinking about my sourdough starter, which i named Gerald after my late father in law, hes been alive going on 11 years now if you count the starter as a continuation which i do, and the thing about a starter is you gotta feed it every single day or it dies just like this battery in the cold except opposite because you WANT gerald cold in the fridge which is the opposite of what this Tom fella is saying about the phone so really somebody should tell him that, anyway gerald had a rough winter last year, almost lost him during the ice storm, my sister in law says you shouldnt name bread but i say you name what you love, and honestly now i forgot what point i was making about the battery, something about enthalpy, my nephew took chemistry and says thats not even a word they use anymore, anyway feed your starters people thats really the whole takeaway here not the goose
I'm not political but that goose situation feels connected to the battery thing somehow and I've already screenshotted this whole page just in case, God bless whoever figures out why first.
forget the goose for one second, the REAL threat to this country is self checkout machines, my grandfather did not survive two tours so I could scan my own bananas, thats a job, give it back to a person
@RealTalk_Gary91 forget the goose for one second, has anyone else noticed the town tornado siren goes off on days there isnt even a storm no more. my neighbor Dale says its testing but I dont buy it, three separate times this month it went off and each time my thoughts felt LOUDER for about a hour after. thats not a coincidence thats a FREQUENCY. anyway my phone lasted till lunch yesterday so make of that what you will.
back in 1987 my Motorola brick phone held a charge for TWO WEEKS in the snow and we were all just fine. nobody talks about THAT. also can we talk about lot 14 at the RV park because Gary over there has been running his generator at 6am for THREE MONTHS and camp managment does nothing
@Betsy_Sovereign1776 brick phones didnt have lithium ion commutes they had a completely different chemistry, this is basic stuff. also birds arent real, they are goverment surveilance drones, everyone knows this, why is nobody addressing THAT in a battery artical
@EagleLiberty_2A oh now your an expert on 1987 phone chemistry? source? SOURCE. no you know what forget the source, lot 14 Gary just put up a SECOND generator and thats the real story here nobody wants to cover
@Betsy_Sovereign1776 THERMODYNAMICS. SUPPLY CHAIN. AGENDA. thats really the whole column when you boil it down, people keep scrolling past the part that matters
BACK IN 1979 A PHONE BATTERY COST FOURTY CENTS AND LASTED A DECADE AND WE NEVER ONCE COMPLAINED. this enthalpy talk is just a fancy word for LAZY ENGINEERING. Consitution doesnt say one word about lithium and thats not an accident.
@Betsy_Sovereign1776 SOURCE? name ONE founding document that even mentions a electrochemical cell. ill wait. ...anyway forget the source, everybody knows its the WALKING that drains it, dogs pull the battery right out through the leash somehow, my cousin who does something with government confirmed this to me personally
Doubt it.
@Betsy_Sovereign1776 my neighbor Dale has had the same charger since Clinton was in office and his phone still works fine walking his beagle in the snow so this whole enthalpy article is one persons problem getting blown up into a national crisis
@Betsy_Sovereign1776 my cousin works at the battery plant, actual government contract work, and he told me both sides of this are wrong, the left says its climate the right says its planned obsolescence and honestly im the only one here being reasonable about the enthalpy situation
@Sgt_Coulomb_Reyes77 your cousin doesnt work in government he works at the kiosk in the mall that sells phone cases, ive seen him, he does not know what a electrochemical cell is
@Cpl_Fenceline_Doyle thats a DIFFERENT cousin, this is my cousin on my mothers side, and frankly the fact you even know what he looks like is concerning to me and should be concerning to everyone reading this
@Betsy_Sovereign1776 Article 9 of the Founders Memo literally covers this, its the one where they specifically warn about electrochemical commutes being used to track dog walks, look it up, theres a Supreme Court ruling called Frostbite v. Commute Board from like 1962 that already settled the whole thing and nobody ever brings it up
@Betsy_Sovereign1776 do your own research before you post something like this. everybody knows batteries started going bad the SECOND the 90s hit, thats not a coincidence thats a whole decade, same thing happend to lawnmowers my uncle says
Bless your heart, Betsy.
@Betsy_Sovereign1776 my late husband said the same thing about his old Motorola, bless him. Article 14 of the Founders Memo actually covers battery commutes in cold weather, the Peppercorn ruling settled it back in '58, ask my grandson he's in college for the computers.
Negative.
@Betsy_Sovereign1776 my neighbor Rhonda has the exact same problem, phone at 80% out the door and dead by the mailbox, and if its happening to HER it is happening to THOUSANDS across this country right now today, thats just math. this Tom fella wants to blame it on enthalpy which last I checked isnt even a real unit, its OHMS and VOLTS and thats it, rest is filler to make the newsletter longer.
Wrapped my flip phone in an oven mitt back in 04 and never had a cold battery problem since. Might not be science but it worked for me. Say a prayer for your dog too, cold paws. God bless.
Everyone talking about cold batteries and nobody mentions that PEPPERMINT essential oil rubbed directly on the charging port reverses lithium ion commute fatigue. I sell these. Message me for the starter bundle, not a scam, my aunt does it too.
battery draining fast is your BODY telling you something too. i havent eaten since Tuesday, sunlight only, never felt clearer. Tom should really cover that instead of hiding behind big Enthalpy words
@2ndID_Patricia its spelled COMMUTE not commut, get you're facts strait. also im on hour 60 of sunlight only and my phone battery outlasts me now which tells you everything.
@Soverignty_Now_72 60 hours no food is not sunlight power its called not eating, my kid tried something like that for a participation trophy diet challenge on the internet and we had to take him to urgent care. kids today got no common sense, back in my day we ate a sandwich and went outside
@Soverignty_Now_72 my neighbor Gary's phone died at his own kids soccer practice tuesday and now every single dog owner in like a three county radius is loosing battery, this isnt a coincidence people this is happening EVERYWHERE and nobody wants to admit it
reminds me of my nephew who wears them wholesale leggings, buttery soft, restocking Tuesday, ask me about the starter kit if you want a pair before they're gone. anyway hope Karen's dog is doing okay in the cold too God bless
im not political but this whole lithium ion commute thing sounds like something they WANT you to believe so you buy a new phone every 2 years. wake up people its not the cold its planned obsolescence look it up
@Sgt_ColdStart_1991 brother this is a science column about batteries in winter not a government briefing. its literally just chemistry slow down in the cold. read past the headline for once
@Squared_Away_Doug ive screenshotted this entire exchange for reasons that will become clear later. some of us pay attention Doug. some of us.
Source?
@Sgt_ColdStart_1991 SCREENSHOT IT. SAVE IT. SHARE IT. this is exactly the kind of thing they dont want circulating and i for one am not surprised, not even a little