[HN Gopher] BU-808: How to Prolong Lithium-based Batteries (2023)
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BU-808: How to Prolong Lithium-based Batteries (2023)
Author : eswat
Score : 66 points
Date : 2026-01-23 06:34 UTC (2 days ago)
(HTM) web link (www.batteryuniversity.com)
(TXT) w3m dump (www.batteryuniversity.com)
| JamesTRexx wrote:
| After the first battery of my Samsung S4 expanded at the end of
| its life in less than 2 years, I found a utility that didn't work
| perfectly but could limit charge anywhere between 30 to 100% most
| of the time, and it prolonged the lifetime of the couple of later
| batteries during the 10+ years I used the phone with a limit
| around 66%.
|
| I was glad to see my new Samsung XCover 7 has a built-in option
| to limit charge to 80%, although a flaky usb cable could
| sometimes overcharge to 100%. And also has a removable battery.
| Mistletoe wrote:
| You only charged your phone to 66% for ten years?
| gattilorenz wrote:
| Veeeeery slow charger :)
|
| But yeah, at some point we should also consider the tradeoff
| between convenience and battery life. Batteries can be
| replaced, having to charge twice a day is a PITA for me.
| BLKNSLVR wrote:
| My charging solution is that I've purchased three (cheap
| and therefore slow) wireless charging docks that sit my
| phone slightly leaning backwards, therefore nicely viewable
| if necessary.
|
| One sits on my desk at work, one sits on my desk at home
| and the third sits on my bedside table (it acts like a
| clock radio / alarm clock). I just place it on the relevant
| charger while working / sleeping and it's always got enough
| charge when I need it.
|
| (I also use the surprisingly fairly recent addition of
| charging protection to limit it to 80% charge)
|
| I'm aware this won't work for all use cases, but it's great
| for mine.
| stavros wrote:
| Those really make my phone overheat, so I avoid them.
| Didn't they heat yours up?
| simulator5g wrote:
| They're a joke, I used to have one in my car and the
| combination of sunlight & internally produced heat would
| make my phone shut off & display a "iPhone is too hot"
| message. Even when it's cold outside.
| jwiz wrote:
| I think that's just sun+charging, not wireless charging
| specific.
| simulator5g wrote:
| I switched to wired charging with the phone mounted in
| the same spot and the heat issue went away. Wireless
| charging produces a lot more heat than wired.
| BLKNSLVR wrote:
| Time for a new Vapor Cooled iphone?!
|
| /s
| BLKNSLVR wrote:
| Sometimes the phone is warm, I wouldn't even say hot.
| Could be because I bought lower wattage wireless chargers
| - I don't need it to charge fast, I just need it to top
| up the battery.
|
| The only time my phone has given me a message about heat
| was, indeed, in a phone holder in the car, but it wasn't
| even charging. We are experiencing a heat wave in
| Australia right now though, and the car had been sitting
| in the sun in a car park for an hour.
| vladvasiliu wrote:
| I definitely would do that if I could. I would absolutely
| love to tell it to only charge to 66% (or whatever, even 50%
| would work). I rarely use the phone for multiple hours at a
| time without access to power, and when I do, I usually know
| beforehand (like during a trip or something) so I could tell
| it to charge all the way. My battery rarely goes below 80%,
| even now that the phone is 3.5 years old.
|
| I understand newer iphones now have the option to only charge
| up to a certain percentage. Mine doesn't have that, it only
| has the "smart charging", which tries not to charge it too
| quickly and only is full by the time it expects you'll use it
| (usually in the morning). It's very hit and miss for my use
| patterns, so it ends up at 100% most of the time...
| sandreas wrote:
| It's probably not a flaky USB cable. Androids charging limit of
| 80% includes a policy to charge 100% every 14 days to
| recalibrate the battery controller.
|
| A possibility to limit charging to ~65% does not exist per se
| but you can measure the time it takes to charge from 25% to 65%
| and use a power timer to shut down charging after that period
| of time. It's not accurate but easy to implement.
|
| Another factor is fast charging... The battery loses capscity
| significantly faster if you fast charge often...
|
| I personally only use the 80% limitation...
| avidiax wrote:
| Maybe I just expect too much battery life, but I find that I
| get quite low or even run out when I limit charging to 80%.
|
| My feeling is that the coulomb counting on the Pixel 8 Pro is
| just not very accurate, so the phone thinks it's at 80%, but
| is really at 60% or 40%.
|
| I still use the feature, but now I have to top up during the
| day every so often. I suppose rationally I should just charge
| to 100% rather than take a medicine that causes the same side
| effect as the disease its meant to treat, but I'm not that
| rational.
| sandreas wrote:
| Absolutely. I find it strange that Google decides to
| provide a fixed value of 80%. A slider from 65% to 95%
| would be more sufficient...
|
| 95% would probably work out for you and still decrease
| battery wearout...
| kevin_thibedeau wrote:
| > although a flaky usb cable could sometimes overcharge
|
| The charge controller is in the phone. The cable and power
| supply have no bearing on when charging is terminated. Android
| has an "optimized charging" option where it will charge above
| 80% shortly before it predicts you are likely to unplug.
| Samsung may have meddled with this behavior but that isn't
| Android's fault.
| user_7832 wrote:
| +1 for battery university, they're an excellent source. Does
| anyone have any other suggestions for similarly technically deep
| (while approachable) articles on any other facet consumer
| electronics?
|
| My understanding from this article is that:
|
| 1. Charge the battery to as low a max percentage as possible
| (till about 65%) 2. Keep it as cool as possible (up to zero
| degrees C at least) 3. Use it as little as possible before
| recharging it (minimize charge-discharge bandwidth)
|
| Aka, over-rate and over size the battery if you're building the
| device, and minimize extremes on any side of soc (state of
| charge).
|
| Do EV manufacturers use any other tricks not covered by this?
|
| (Of course, use the device as needed, these are just guidelines
| for the best perfomance.)
| stavros wrote:
| I don't think this advice is useful. You're going to use your
| devices, so you won't control the temperature or, largely, the
| charge percentage.
|
| I think good advice is to keep your devices as cool as you can
| (ie don't leave your cars in sunlight when there's shade),
| which you probably did anyway, and keep the battery between 20%
| and 80% as much as possible. If the battery is going to stay
| unused for a while, leave it at 3.8V (or close to it), or at
| 50%.
|
| Batteries are ultimately consumables, so don't stress too much.
| Just care for them as much as convenient, and that's it.
| user_7832 wrote:
| > You're going to use your devices, so you won't control the
| temperature or, largely, the charge percentage.
|
| > I think good advice is to keep your devices as cool as you
| can (...), and keep the battery between 20% and 80% as much
| as possible.
|
| Yeah that's kinda what I meant. Where it's easy or possible
| to do so (for eg lots of modern laptops & phones allow charge
| limits), it's better to follow these guidelines.
|
| > Batteries are ultimately consumables, so don't stress too
| much. Just care for them as much as convenient, and that's
| it.
|
| Yeah I agree (and that's what I meant by my last sentence),
| however, a lot of people (including eg my dad!) end up having
| battery issues while being unaware that they can do things to
| protect their hardware.
|
| For example, my phone has enough capacity to last the whole
| day even at 60% of it's capacity. I've set it to stop
| charging at 80% (the lowest possible SOC) for this reason. On
| my laptop, I frequently reduce it to 60% as I use it plugged
| in.
|
| > I don't think this advice is useful.
|
| I'm afraid I don't get what's not helpful? We're probably
| talking across each other.
| stavros wrote:
| It came across to me as "keep your batteries always under 0
| C", which obviously almost nobody can do, and it leads to a
| sense of "eh, I won't go to these lengths, might as well do
| nothing", which is counterproductive.
|
| I see the same reaction with healthy eating, where people
| are so put off by extremely militant advice that they think
| "I can't eat only vegetables all day, fuck it, I'll eat
| these three cheeseburgers".
|
| I agree with your second comment, the first one just could
| be misconstrued as very hard-to-follow advice.
| Filligree wrote:
| That's backwards. At _too_ low temperatures batteries
| start to take damage during discharge or (especially)
| charge, so 0C is the lowest temperature at which you
| should charge it. 5C would be better.
|
| It's a concern mainly for e.g. offgrid batteries being
| used in the winter.
| stavros wrote:
| I know, but "as cool as possible (up to zero degrees C at
| least)" is conflicting, and kind of means "below zero
| degrees".
| VorpalWay wrote:
| > I think good advice is to keep your devices as cool as you
| can (ie don't leave your cars in sunlight when there's
| shade),
|
| In some climates, such as where I live, the larger issue is
| the cold in the winter. From what I understand, Li-ion
| batteries don't like being charged below 0 C. And it is not
| uncommon for it to dip to -15 C or even -20 C here.
|
| Really, from what I understand, batteries want to be kept
| above freezing but cool. So yeah, don't leave it in direct
| sunlight in the middle of summer. The more difficult problem
| is the winter (unless you happen to have a heated garage).
| stavros wrote:
| Yeah, they lose capacity temporarily when it's very cold.
| Most EVs now precondition the battery before charging by
| heating it up.
| SV_BubbleTime wrote:
| > Do EV manufacturers use any other tricks not covered by this?
|
| Automotive EE here. EV aren't ready for world wide use. That
| statement is constantly ignored by people in California who see
| zero issues with their new expensive fancy cars.
|
| Shortest version... The heating and cooling systems of the
| battery are there to prevent damage. BUT... who powers the
| heating and cooling systems? The battery of course.
|
| In a traditional or better yet a plugin hybrid, you can use the
| gas engine to control how much electric you are using in
| conditions that would be harmful to the battery. In EV vehicles
| you have no choice. The car won't tell you "you can't drive
| right now".
|
| The marketing of EVs was a mistake, and every mfg is paying for
| it. Ford taking a 2 billion write off this year on their EV
| line and canceling a lot of their vehicles.
|
| They will be cool, but this generation makes a great second
| vehicle or town vehicle. Absolutely not an extreme weather
| highway vehicle.
| user_7832 wrote:
| > EV aren't ready for world wide use.
|
| Fully agree (I'm 100% team PHEV or EREV/REEV) as a mechanical
| engineer. IMO BEVs and PHEVs/REEVs should be on parity in
| terms of tax/govt incentives, while encouraging electric use
| - for eg, subsidized (PH)EV charging, high(er) costs in city
| centres if running in ICE mode, etc.
|
| I was just curious if EV manufacturers use any other tricks
| that're "well known" in EV-land but not for the average
| consumer.
| kanbankaren wrote:
| AFAIK, they charge only to 4.0 V. I think the batteries on
| satellites are also charged only to 4.0 V
| user_7832 wrote:
| Thanks! That's very helpful (and unsurprising) to know.
| Any idea if satellites use LTO batteries btw? They have
| much longer lives and apparently can tolerate much more
| abuse.
| simulator5g wrote:
| These acronyms are a nightmare, what the hell is a PHEV?
| EREV? PZEV? Consumers are just expected to know this stuff
| somehow, it's nuts. Sometimes I buy parts for my car and
| just hope I selected the right one, because some models are
| PZEV/not PZEV but the sticker that would tell me has turned
| completely white & can't be read.
| fragmede wrote:
| Consumers just take their shit to the dealer which hires
| technicians who job it is, literally, to know "what the
| hell". If that is too complicated for you to figure out,
| I can't recommend you do your own work on your car.
| user_7832 wrote:
| > These acronyms are a nightmare, what the hell is a
| PHEV? EREV? PZEV?
|
| PHEV is the old term, it's a plug in hybrid EV. I.e., you
| can plug it in and use the battery, or use the ICE engine
| via petrol (gasoline).
|
| (B)EVs are pure battery EVs. Think Tesla.
|
| REEV/EREV is range extender EV. Essentially an EV that
| has a small ICE engine that's very handy for making the
| 50 or 100km battery "run" for 500km if the need arises,
| by using the ICE as a generator.
|
| In some countries, you also have "strong" and "weak"
| hybrids - these are _not_ cars you can plug in (they only
| take petrol), _but_ they use some motors and battery to
| vastly improve the efficiency of the engine. Think
| doubling your mileage levels of good.
|
| > Consumers are just expected to know this stuff somehow,
| it's nuts.
|
| Yeah no I don't think that's good design either. May I
| ask what kind of parts do you buy that makes it so
| confusing? Our car (Honda) has a very simple model name,
| there's not a lot of variations or options to confuse to
| begin with.
|
| Btw, if you want a real fun doozy, look up the parallel
| series hybrid system that iirc GM had. It was a
| _beautiful_ beast - it could basically take any power
| source, and do anything with it (charge battery, run
| wheels etc). There 's a good YouTube video on it if you
| search for it.
| simulator5g wrote:
| Whenever I buy parts for my regular gas car the parts
| site asks if it's PZEV or DOHC. To make matters worse the
| PZEV version is also DOHC (dual over head cams) as far as
| I can tell. And the VIN number doesn't say if it's PZEV
| or not. It's not on any of the paperwork I got with the
| car either.
| user_7832 wrote:
| I don't know why I'm being downvoted, but I live in a
| developing country where the tailpipe emissions from a
| modern well maintained car are literally cleaner than that
| of commercial (power) plants - potentially making EVs
| _worse_. Ofc I 'm sure it's much nicer if you're in a 1st
| world country, but unfortunately that's not where I am.
| pengaru wrote:
| How is this not an instance of "perfect is the enemy of good
| enough?"?
| SV_BubbleTime wrote:
| Depends.
|
| I have a vehicle in my personal shop right now. It needs a
| new battery, it is effectively totaled.
|
| The battery costs more than the vehicle.
|
| The effort for me to replace the battery modules (not even
| the cells inside of them) involves taking the entire
| suspension out, and then, you have the ACTUALLY FATAL issue
| of working on the battery pack. You need 1000V+ gloves that
| expire every six months, composite ratchets and sockets,
| and for me high voltage certification.
|
| There is nothing on an ICE vehicle that can kill you while
| working on its parts.
|
| I will be downvoted by people who need (literally) to
| defend their purchase. Always am on this topic.
| user_7832 wrote:
| Honestly in this situation, _hybrids_ (ideally of the plug
| in variant) are the "good enough" thing when you're
| shifting from ICE.
|
| Shifting the easy 70% first gives a very nice boost, and
| the rest can be cajoled/fed hydrogen (if it matures by
| then) etc over time.
| kuerbel wrote:
| ...what? You leave your car plugged in, and that's it. Then
| the BMS will take care of the battery without having to use
| it's energy.
|
| If I preheat the car it also preheats the battery. If it's
| not warm enough it won't allow full recuperation. Oh my god,
| I have to use THE BRAKES for a few minutes, literal trash
| car.
|
| And all those people in Norway, you know, with their heat
| pumps and EVs. Obviously life just grinds to a halt there
| every winter. *dramatic eye roll
| SV_BubbleTime wrote:
| Cool. And when you need to drive it? Most systems do not
| keep the battery heater running indefinitely.
|
| No one is talking about the brakes.
|
| I'm an automotive engineer that has worked for two of the
| big4. What is your experience?
| kuerbel wrote:
| driving an ev for the past 2.5 years with 97% SOH
| remaining. So I must be doing something right wrt
| treating the battery nicely. And I don't have a garage,
| it's outside most of the time. I drove thousands of km in
| subzero C temperature.
|
| >Cool. And when you need to drive it? Most systems do not
| keep the battery heater running indefinitely.
|
| I get in and put it into drive. When it's cold, I preheat
| it, I can program departure times, so the battery is
| conditioned and the cabin warmed in advance. Even at sub-
| zero temperatures, it always starts reliably, unlike a
| diesel engine, which, as you know, requires preheating
| and can struggle with extreme cold starts. Also requires
| winter diesel.
| ninalanyon wrote:
| > And when you need to drive it?
|
| When I need to drive me EV I open the door, get in, close
| the door, put it in drive and drive off.
|
| Were you expecting something different? I'm in Norway by
| the way where it is expected to be -15 C in a few days;
| after eight years of EV driving (2015 Tesla S 70D) I am
| not anticipating any problems.
|
| > What is your experience?
|
| I've told you mine, what's yours? Or will you argue from
| authority again?
| ninalanyon wrote:
| They seem to be working just fine here in snowy Norway.
| s-y wrote:
| Are you a technician or an engineer? And as a follow up, what
| part of the vehicle do you engineer?
|
| Because this sounds a lot like a case of a dentist seeing a
| lot of cavities and making conclusions that teeth are "bad
| tech".
|
| I live in a climate that's in yearly flux from -20 to +35 C
| and EVs have been normal here for a long time(7+ years) with
| no major issues. What parameters and therefore regions does
| your statement cover? I'm sure you can't run an EV in
| Syberia(RU), but people with petrol cars there have to run
| them even parked to avoid freezing during the winter so there
| will always be extremes.
|
| As for the commercial equation: BYD and Tesla don't seem to
| be fitting that narrative. So this is not a matter of a
| marketing mistake - but an overall execution on the failed
| manufacturers.
| SV_BubbleTime wrote:
| Engineer. I started in core competency groups, worked on
| powertrain integration, and now, I'm a specialist. I roam
| around and put myself to use wherever needed. I'm now a
| consultant but I have badges for idk, maybe 20 facilities.
| bahmboo wrote:
| I don't see anything in your comment history that would
| indicate a strong engineering role. Mostly political
| engagements really. You haven't said anything useful on
| this thread regarding TFA and it's content. Listing your
| credentials while making obviously false and dismissive
| statements is not good faith discussion.
| HPsquared wrote:
| Light bulbs (including LEDs) are similar. If you use them at
| slightly lower then their maximum rating, things tend to last a
| LOT longer. The "Dubai lamp" uses this concept - oversized LEDs
| that are derated, and last a very long time (100k hours). You
| can do the same by buying oversized dimmable LEDs and simply
| turning down the brightness.
| averynicepen wrote:
| Degradation is driven by many things, but a big one is heat.
| Elevated temperatures during both charge and discharge is very
| bad for battery longevity. To manage this, almost all EVs use
| liquid cooling, with a cold plate directly contacting as many
| battery cells as they can to move heat out of the battery. This
| coolant is then cooled by a radiator, an AC chiller, or both.
|
| The worst temperature abuse case is DC fast charging, aka
| Supercharging, where high current charging creates tons of heat
| due to resistive losses. This is why frequent fast charging
| causes faster battery degradation, but ordinary charging and
| driving does not, because the coolant loop is sized for the DC
| fast charge heat transfer requirements.
|
| Besides removing heat, adding heat into the system is also
| desirable. Cold weather environments approaching freezing or
| below is also bad for battery longevity, and more importantly,
| terrible for range. Resistive heaters are super power hungry,
| and to heat the battery coolant loop requires power from the
| battery. This is why, conventionally, EVs are terrible in cold
| weather.
|
| > Do EV manufacturers use any other tricks not covered by this?
|
| And now, onto the magic trick.
|
| Heat management is so important to both the driving range and
| the longevity of a vehicle that EVs have moved from traditional
| resistive heaters to heat pumps. These magical thermodynamic
| devices can move heat from anywhere, including drawing heat out
| of cold ambient air.
|
| When you combine that with a valve design that allows the heat
| pump to access the battery coolant loop, the motor drivetrain
| coolant loop, the cabin coolant loop, the vehicle computer(s)
| coolant loops, and external ambient temperature, you can have a
| super efficient system that shuffles heat where it's "wasted"
| to where it's "needed".
|
| Tesla has an excellent video briefly covering their heat pump
| and their very clever Octovalve design:
| https://www.youtube.com/watch?v=DyGgrkeds5U
|
| For more depth, this video covers the heat pump and the ~22
| different sources of heat it can draw heat from:
| https://www.youtube.com/watch?v=Dujr3DRkpDU
| bullen wrote:
| Between 50% 3.7V and 80% ~4-4.2V is the best.
|
| Don' let the voltage go to far below 3.7V and don't over charge
| above ~4-4.2V.
| notherhack wrote:
| Reminds me of "Chargie", a gadget that goes inline with your USB
| charging cable and controlled by an app on the device to limit
| the charge level to whatever you choose. I think it was born via
| kickstarter. "The most Intelligent Battery Health
| Protection for Phones & Laptops" https://chargie.org/
| avidiax wrote:
| I may be a bit odd, but I store lithium ion battery containing
| electronics in the vegetable drawer in the fridge. You lose 20%
| of capacity in a year if you have 100% state of charge but only
| 6% loss of capacity at refrigerator temperatures. So tool
| batteries, small electronics and whatever else that isn't used
| weekly gets put in.
|
| I also try to charge fully only just before use (and only if I
| need 100%), and store at partial charge. If I am charging for
| storage, I just set a 30 minute timer. Since 1C charging is the
| most common, 30 minutes at 1C will be about 50% state of charge
| from empty, which is useful for items with no state of charge
| indicator.
|
| I use AlDente[1] on my Apple laptops, and the 80% charge feature
| on my Pixel phone. My bedside phone charger is a slow charger.
|
| Maybe I'm doing too much to manage my batteries, but I also
| haven't needed to retire anything for having a bad battery in
| many years, nor had items with dwindling capacity.
|
| [1] https://github.com/AppHouseKitchen/AlDente-
| Battery_Care_and_...
| gruez wrote:
| >You lose 20% of capacity in a year if you have 100% state of
| charge but only 6% loss of capacity at refrigerator
| temperatures.
|
| Source? The common figure for smartphone batteries is " _at
| least_ 80% capacity after 2 years ", and that presumably
| includes cycles, not just leaving it charged.
| avidiax wrote:
| From the article, Table 3: 100% SoC @ 25degC leaves only 80%
| of the original capacity after a year.
|
| It's easy to look at that table and think that it's remaining
| charge after a year; it's not. It's lost capacity.
|
| This is known in the industry as "calendar aging". So far as
| I know, stockpiles of lithium ion batteries are stored at a
| relatively low state of charge and in a cold environment for
| this reason among others. It's common to order a laptop
| battery or similar and get a unit that was manufactured a
| year back. It would be terrible to get a new battery that
| already had diminished capacity, which is what would happen
| if you stored them in a non-conditioned warehouse in a hot
| climate.
| averynicepen wrote:
| Have you ever measured your battery voltages over time storing
| it this way? Is that 6% capacity loss theoretical or measured
| data? I'm intrigued. This sounds crazy, but it should
| technically be fundamentally sound.
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