8 ms·

Discovery could extend battery life by replacing tape that causes self‑discharge

NickBusey 4y ago
This sounds like a small tweak in the manufacturing process that could lead to potentially very large gains down the road. Fantastic work!
- giuliomagnifico 4y ago
  Yes exactly why I posted it. A little improvement that can be real in few time, instead of some groundbreaking researches that will never be used in daily life (in the next few years).
- abracadaniel 4y ago
  You weren't kidding. Just switching out the tape material is all it takes? I wonder how frequently PET based tapes are used. I'd assume any of the pouch type batteries could be impacted, so phones/laptops/etc. Fascinating that it wasn't noticed until now.
- kazinator 4y ago
  We shouldn't rush to the conclusion of large gains; this plugs a tiny leak which affects equipment that is used sporadically between long idle times, which is a specific use case. This could reduce the number of service visits to battery-powered, low-current-draw remote sensing equipment and such. In that sort of use case, it could be a big deal.
  - hex4def6 4y ago
    Exactly. This is not going to make a meaningful difference in devices that you charge on a daily / weekly basis (cell phones, laptops, smart watches). Additionally, there's a significant portion of "self discharge" of lithium packs that is actually the battery protection circuitry (BMS). That's not to say this isn't a good catch; like you mention, low power devices that you want to go months between charges may benefit significantly.
lern_too_spel 4y ago
Previously discussed: https://news.ycombinator.com/item?id=34582931 https://news.ycombinator.com/item?id=34582931
lockhouse 4y ago
Honest and tangentially related question…has anyone else noticed that Apple devices hold their battery life in suspend mode way better than Windows, Android, or Linux ones do? My kids mostly only use their Kindle Fire tablets on the weekends and even if they get fully charged Sunday night, they’re running on fumes by Friday, even if they’ve been completely unused in the interim. Meanwhile, I have an iPhone from my employer that I usually top off once a week, but it’s still well over 80% most of the time during the same period. What magic is Apple using here?
- izacus 4y ago
  It's the magic of "not being allowed to run anything". If you kill -9 all your Linux processes then you'll be great at idle use as well. Now hunting down all the processes that might be turning on your radios, CPUs and I/O devices is the hard part on OSes where you can actually run things in the background, since you easily get into tragedy of the commons situations. For comparison, consider a Kindle (linux device, battery lasts for weeks) or a Garmin watch (battery life is about 3-10x better than Apple watch) to see how different can outcomes be if you control what processes run.
  - colanderman 4y ago
    Processes don't run while a computer is in suspend mode.
    - izacus 4y ago
      Of course they do on modern computers (so do peripheral microcontrollers). Most modern laptops and devices don't go into full suspend states anymore, they just do a much lighter standby similar to phones and tablets. Windows calls this "Modern Standby" while Apple just does it since Apple Sillicon. Even so, periodically they will wake up and run tasks just like phones (e.g. Power Nap on Apples, no idea what Windows calls it). Linux has a headache here because it's mostly not prepared to disable all their processes and peripherals correctly during those states so something keeps waking up and running.
joecool1029 4y ago
I wonder if they'll switch to polyacrylamide (kapton) tape. It's already used on packs pretty frequently just not on the tabs. Heat shouldn't damage this material.
- andrewxdiamond 4y ago
  Kapton tape is also quite expensive and overqualified for this task. I think the engineers will be able to squeeze out a lot cost by using something more “barely-capable”
  - tuatoru 4y ago
    Cellulose tape?
    - joecool1029 4y ago
      That would be among the worst choices for tape. Gets damaged above 50C, decomposes above 100C, biodegradable and flammable: https://s3-ap-southeast-2.amazonaws.com/wc-prod-pim/Asset_Documents/Sellotape%20Label%20Tape%20SDS.pdf https://s3-ap-southeast-2.amazonaws.com/wc-prod-pim/Asset_Do... Might as well seal it with the yellow adhesive Cyberpower uses on their UPS's which decomposes into flammable and conductive substances.
- astangl 4y ago
  I was actually just reading about Kapton yesterday, and stumbled upon some info about its deterioration being hastened by heat. See https://en.m.wikipedia.org/wiki/Kapton#Characteristics https://en.m.wikipedia.org/wiki/Kapton#Characteristics
- mitthrowaway2 4y ago
  Kapton tape is polyimide, not polyacrylamide, isn't it?
  - joecool1029 4y ago
    Thanks you're correct, polyacrylamide is a cool unrelated material.
hedora 4y ago
The problem is that PET plastic leaches chemicals at sub-boiling temperatures. PET plastic bottles are frequently used to hold food and beverages, and considered "safe" by the industry, despite research that suggests they leach endocrine disruptors into food.
- tuatoru 4y ago
  PET containers are so widely used that if there were an actual problem with them, people would be dying--or at least ill--in millions.
  - chrismeller 4y ago
    I think you’re over-exaggerating the impact to dismiss the premise. Endocrine disrupters don’t generally lead to death, they lead to developmental and hormone disorders, ADHD, etc. All of these things are on the uptick.
    - vorpalhex 4y ago
      Our ability to diagnose those things is also improving yearly...
      - KMag 4y ago
        Our ability to count sperm cells, for instance, isn't decreasing yearly.
  - TheSpiceIsLife 4y ago
    Talk about lacking nuance. Health isn't binary: alive or dead. Something like one in three people will get cancer at some point. It's possible endocrine disruptors contribute to that rare.
    - lazide 4y ago
      Something kills us eventually. Heart attacks, accidents, violence, disease, cancer, etc. Reduce one major cause (violence) or two or three (accidents, disease), and voila - the other elements take over their portions of the pie. That an all the nuke testing fallout, tire dust, random nasty crap, etc.
supernova87a 4y ago
I have a personal anecdote that is maybe related? I store some spare car/boat batteries in my garage, and you would think that batteries, in their plastic/insulated containers, should be fairly inert or impervious to odd discharge effects. However, over years, I have noticed that if batteries are left on the bare floor of a garage, they will discharge over time. Something to do with gradual leakage via the plastic contacting ground (and maybe plus humidity) -- there is some conduction going on! So instead, you have to store them on well-insulating platforms, say styrofoam or acrylic, and they will hold their charge far longer. But this is on the timescale of months -- I wonder how that relates to the timescale these researchers are investigating (and for often used batteries, I would imagine it matters less). These little parasitic losses that are rarely studied...
- slug 4y ago
  Another hypothesis: I think that the batteries on the floor will be colder, so are prone to lose charge / fail faster (internal discharge through plates). Being colder (due to being on the floor) could also bring water vapor condensation on the battery surface, so that could be a path of external discharge (between the battery terminals).
  - mmmwww 4y ago
    That’s what I would have thought as well.
  - Maursault 4y ago
    > I think that the batteries on the floor will be colder, so are prone to lose charge / fail faster (internal discharge through plates). Cold is good, as long as the air is very dry. It will reduce self-discharge. > Being colder (due to being on the floor) could also bring water vapor condensation on the battery surface, so that could be a path of external discharge (between the battery terminals). Bingo. Warmer air holds more water, and as the temperature drops, because cooler air can't hold as much water, it will condensate out and form droplets. Water and moisture are bad for cells, even humidity is bad. A garage is usually not climate controlled. Some awesome folks do climate control their garage, most don't though. Whatever the %RH outside is, the garage will follow. Most US states have a surprisingly high average %RH.

This sounds like a small tweak in the manufacturing process that could lead to potentially very large gains down the road. Fantastic work!

giuliomagnifico 4y ago
Yes exactly why I posted it. A little improvement that can be real in few time, instead of some groundbreaking researches that will never be used in daily life (in the next few years).
abracadaniel 4y ago
You weren't kidding. Just switching out the tape material is all it takes? I wonder how frequently PET based tapes are used. I'd assume any of the pouch type batteries could be impacted, so phones/laptops/etc. Fascinating that it wasn't noticed until now.
kazinator 4y ago
We shouldn't rush to the conclusion of large gains; this plugs a tiny leak which affects equipment that is used sporadically between long idle times, which is a specific use case. This could reduce the number of service visits to battery-powered, low-current-draw remote sensing equipment and such. In that sort of use case, it could be a big deal.
- hex4def6 4y ago
  Exactly. This is not going to make a meaningful difference in devices that you charge on a daily / weekly basis (cell phones, laptops, smart watches). Additionally, there's a significant portion of "self discharge" of lithium packs that is actually the battery protection circuitry (BMS). That's not to say this isn't a good catch; like you mention, low power devices that you want to go months between charges may benefit significantly.

lern_too_spel 4y ago

Previously discussed: https://news.ycombinator.com/item?id=34582931 https://news.ycombinator.com/item?id=34582931

lockhouse 4y ago

Honest and tangentially related question…has anyone else noticed that Apple devices hold their battery life in suspend mode way better than Windows, Android, or Linux ones do? My kids mostly only use their Kindle Fire tablets on the weekends and even if they get fully charged Sunday night, they’re running on fumes by Friday, even if they’ve been completely unused in the interim. Meanwhile, I have an iPhone from my employer that I usually top off once a week, but it’s still well over 80% most of the time during the same period. What magic is Apple using here?

izacus 4y ago
It's the magic of "not being allowed to run anything". If you kill -9 all your Linux processes then you'll be great at idle use as well. Now hunting down all the processes that might be turning on your radios, CPUs and I/O devices is the hard part on OSes where you can actually run things in the background, since you easily get into tragedy of the commons situations. For comparison, consider a Kindle (linux device, battery lasts for weeks) or a Garmin watch (battery life is about 3-10x better than Apple watch) to see how different can outcomes be if you control what processes run.
- colanderman 4y ago
  Processes don't run while a computer is in suspend mode.
  - izacus 4y ago
    Of course they do on modern computers (so do peripheral microcontrollers). Most modern laptops and devices don't go into full suspend states anymore, they just do a much lighter standby similar to phones and tablets. Windows calls this "Modern Standby" while Apple just does it since Apple Sillicon. Even so, periodically they will wake up and run tasks just like phones (e.g. Power Nap on Apples, no idea what Windows calls it). Linux has a headache here because it's mostly not prepared to disable all their processes and peripherals correctly during those states so something keeps waking up and running.

joecool1029 4y ago

I wonder if they'll switch to polyacrylamide (kapton) tape. It's already used on packs pretty frequently just not on the tabs. Heat shouldn't damage this material.

andrewxdiamond 4y ago
Kapton tape is also quite expensive and overqualified for this task. I think the engineers will be able to squeeze out a lot cost by using something more “barely-capable”
- tuatoru 4y ago
  Cellulose tape?
  - joecool1029 4y ago
    That would be among the worst choices for tape. Gets damaged above 50C, decomposes above 100C, biodegradable and flammable: https://s3-ap-southeast-2.amazonaws.com/wc-prod-pim/Asset_Documents/Sellotape%20Label%20Tape%20SDS.pdf https://s3-ap-southeast-2.amazonaws.com/wc-prod-pim/Asset_Do... Might as well seal it with the yellow adhesive Cyberpower uses on their UPS's which decomposes into flammable and conductive substances.
astangl 4y ago
I was actually just reading about Kapton yesterday, and stumbled upon some info about its deterioration being hastened by heat. See https://en.m.wikipedia.org/wiki/Kapton#Characteristics https://en.m.wikipedia.org/wiki/Kapton#Characteristics
mitthrowaway2 4y ago
Kapton tape is polyimide, not polyacrylamide, isn't it?
- joecool1029 4y ago
  Thanks you're correct, polyacrylamide is a cool unrelated material.

hedora 4y ago

The problem is that PET plastic leaches chemicals at sub-boiling temperatures. PET plastic bottles are frequently used to hold food and beverages, and considered "safe" by the industry, despite research that suggests they leach endocrine disruptors into food.

tuatoru 4y ago
PET containers are so widely used that if there were an actual problem with them, people would be dying--or at least ill--in millions.
- chrismeller 4y ago
  I think you’re over-exaggerating the impact to dismiss the premise. Endocrine disrupters don’t generally lead to death, they lead to developmental and hormone disorders, ADHD, etc. All of these things are on the uptick.
  - vorpalhex 4y ago
    Our ability to diagnose those things is also improving yearly...
    - KMag 4y ago
      Our ability to count sperm cells, for instance, isn't decreasing yearly.
- TheSpiceIsLife 4y ago
  Talk about lacking nuance. Health isn't binary: alive or dead. Something like one in three people will get cancer at some point. It's possible endocrine disruptors contribute to that rare.
  - lazide 4y ago
    Something kills us eventually. Heart attacks, accidents, violence, disease, cancer, etc. Reduce one major cause (violence) or two or three (accidents, disease), and voila - the other elements take over their portions of the pie. That an all the nuke testing fallout, tire dust, random nasty crap, etc.

supernova87a 4y ago

I have a personal anecdote that is maybe related? I store some spare car/boat batteries in my garage, and you would think that batteries, in their plastic/insulated containers, should be fairly inert or impervious to odd discharge effects. However, over years, I have noticed that if batteries are left on the bare floor of a garage, they will discharge over time. Something to do with gradual leakage via the plastic contacting ground (and maybe plus humidity) -- there is some conduction going on! So instead, you have to store them on well-insulating platforms, say styrofoam or acrylic, and they will hold their charge far longer. But this is on the timescale of months -- I wonder how that relates to the timescale these researchers are investigating (and for often used batteries, I would imagine it matters less). These little parasitic losses that are rarely studied...

slug 4y ago
Another hypothesis: I think that the batteries on the floor will be colder, so are prone to lose charge / fail faster (internal discharge through plates). Being colder (due to being on the floor) could also bring water vapor condensation on the battery surface, so that could be a path of external discharge (between the battery terminals).
- mmmwww 4y ago
  That’s what I would have thought as well.
- Maursault 4y ago
  > I think that the batteries on the floor will be colder, so are prone to lose charge / fail faster (internal discharge through plates). Cold is good, as long as the air is very dry. It will reduce self-discharge. > Being colder (due to being on the floor) could also bring water vapor condensation on the battery surface, so that could be a path of external discharge (between the battery terminals). Bingo. Warmer air holds more water, and as the temperature drops, because cooler air can't hold as much water, it will condensate out and form droplets. Water and moisture are bad for cells, even humidity is bad. A garage is usually not climate controlled. Some awesome folks do climate control their garage, most don't though. Whatever the %RH outside is, the garage will follow. Most US states have a surprisingly high average %RH.