8 ms·

BU-808: How to Prolong Lithium-based Batteries (2023)

74 points by eswat 8mo ago

JamesTRexx 8mo ago
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 8mo ago
  You only charged your phone to 66% for ten years?
  - gattilorenz 8mo ago
    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 8mo ago
      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 8mo ago
        Those really make my phone overheat, so I avoid them. Didn't they heat yours up?
        simulator5g 8mo ago
        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 8mo ago
        I think that's just sun+charging, not wireless charging specific.
        simulator5g 8mo ago
        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 8mo ago
        That's really quite interesting. I know the wireless charging uses more power to deliver less power, so there's heat generation due to the loss of power in the transfer (I'm assuming that's how it works). But, I figured that the battery would heat up more the faster it's being charged, and so wired charging at the same wattage would heat the battery more than wireless charging. Must be a lot of power->heat transfer loss with wireless charging.
        BLKNSLVR 8mo ago
        Time for a new Vapor Cooled iphone?! /s
        BLKNSLVR 8mo ago
        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 8mo ago
    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 8mo ago
  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 8mo ago
    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 8mo ago
      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 8mo ago
  > 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 8mo ago
+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 8mo ago
  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 8mo ago
    > 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.
bullen 8mo ago
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 8mo ago
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 8mo ago
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_Monitoring https://github.com/AppHouseKitchen/AlDente-Battery_Care_and_...
- gruez 8mo ago
  >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 8mo ago
    From the article, Table 3: 100% SoC @ 25°C 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 8mo ago
greentea23 8mo ago
One of the biggest reasons I still prefer to root my phone is to use acc https://github.com/VR-25/acc https://github.com/VR-25/acc. It's criminal that you have to root to run code that reduces charging speed or shuts the phone down automatically. I have it shut down at 20% and charge to 80% except when I know I will need to be out for an extended period without a charger.
1970-01-01 8mo ago
Note that the title is slightly misleading. If you didn't know, lithium-based could mean lithium phosphate, lithium titanate, or lithium ion (or other lithium chemistry). This guide is targeting lithium ion cells.
CrimsonCape 8mo ago
It's unfortunate that there is huge interest in prolonging lithium battery life because it's an indication of products with hard-to-replace batteries. protected lithium cells are fairly save and easy to replace into devices designed for them. Lifepo4 cells similarly. We need more product engineers out there fighting the good fight.

74 points by eswat 8mo ago

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 8mo ago
You only charged your phone to 66% for ten years?
- gattilorenz 8mo ago
  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 8mo ago
    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 8mo ago
      Those really make my phone overheat, so I avoid them. Didn't they heat yours up?
      - simulator5g 8mo ago
        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 8mo ago
        I think that's just sun+charging, not wireless charging specific.
        simulator5g 8mo ago
        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 8mo ago
        That's really quite interesting. I know the wireless charging uses more power to deliver less power, so there's heat generation due to the loss of power in the transfer (I'm assuming that's how it works). But, I figured that the battery would heat up more the faster it's being charged, and so wired charging at the same wattage would heat the battery more than wireless charging. Must be a lot of power->heat transfer loss with wireless charging.
        BLKNSLVR 8mo ago
        Time for a new Vapor Cooled iphone?! /s
      - BLKNSLVR 8mo ago
        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 8mo ago
  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 8mo ago
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 8mo ago
  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 8mo ago
    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 8mo ago
> 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 8mo ago

+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 8mo ago
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 8mo ago
  > 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.

bullen 8mo ago

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 8mo ago

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 8mo ago

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_Monitoring https://github.com/AppHouseKitchen/AlDente-Battery_Care_and_...

gruez 8mo ago
>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 8mo ago
  From the article, Table 3: 100% SoC @ 25°C 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 8mo ago

greentea23 8mo ago

One of the biggest reasons I still prefer to root my phone is to use acc https://github.com/VR-25/acc https://github.com/VR-25/acc. It's criminal that you have to root to run code that reduces charging speed or shuts the phone down automatically. I have it shut down at 20% and charge to 80% except when I know I will need to be out for an extended period without a charger.

1970-01-01 8mo ago

Note that the title is slightly misleading. If you didn't know, lithium-based could mean lithium phosphate, lithium titanate, or lithium ion (or other lithium chemistry). This guide is targeting lithium ion cells.

CrimsonCape 8mo ago

It's unfortunate that there is huge interest in prolonging lithium battery life because it's an indication of products with hard-to-replace batteries. protected lithium cells are fairly save and easy to replace into devices designed for them. Lifepo4 cells similarly. We need more product engineers out there fighting the good fight.