[HN Gopher] Discovery could extend battery life by replacing tap...
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Discovery could extend battery life by replacing tape that causes
self-discharge
Author : giuliomagnifico
Score : 74 points
Date : 2023-01-31 17:47 UTC (5 hours ago)
(HTM) web link (www.dal.ca)
(TXT) w3m dump (www.dal.ca)
| joecool1029 wrote:
| 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 wrote:
| 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 wrote:
| Cellulose tape?
| astangl wrote:
| 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
| lockhouse wrote:
| 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?
| dahfizz wrote:
| My experience is the opposite. My company gave me an M1 mac
| that I leave plugged while I work. It is at 100% when I shut it
| down Friday afternoon, and its at around 40% when I boot it up
| on Monday morning.
|
| I suspect the battery is defective, but like I said I leave it
| docked when I work anyway so I don't really care.
| GoToRO wrote:
| The "magic" is no features. For example All day events can have
| a notification at 9:00AM and that's it. You can't change it.
| You can't have 100 events with different notification times.
| The phone only has to wake up at 9:00, check the events and
| that"s it. There are many, many examples like this on the
| iPhone.
| bradyd wrote:
| That's just a stupid limitation of the UI on the iPhone. On a
| Mac you can set a custom time, which triggers just fine on an
| iPhone.
| tshaddox wrote:
| > For example All day events can have a notification at
| 9:00AM and that's it.
|
| That's a bizarre limitation that they should fix, but I don't
| think it implies anything about how iPhones work in standby.
| Alarms, timers, reminders, push notifications, etc. seem to
| work fine in standby (although I'm sure standby battery life
| is affected by how often those are happening).
| izacus wrote:
| 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.
| Saturate7246 wrote:
| I have quite an old samsung tablet that, when I keep wifi and
| bluetooth turned off in LineageOS, has just this week surprised
| me as I had fully charged it and hadn't used it in about a
| month or so, it still had 70% battery life left. It may have
| even been closer to two months, I can't be sure.
|
| But if I leave the wifi on, even with syncthing/etc not running
| at all, it will last about as long as you'd expect an unused
| android tablet to.
|
| I'm sure it's many tricks adding to one great feat, but I've
| always guessed that many of these devices could probably be
| better optimized for what is ironically their primary use case:
| using low amounts of power in standby while still able to relay
| important information as needed.
|
| But if that's any part of the apple magic, how does the trick
| work, and why aren't more devices doing similar things?
| kevin_thibedeau wrote:
| For Android just leave battery saver permanently enabled at
| 100% charge. You lose animations and haptic feedback but it
| cuts down on radio usage and extends battery life.
| LeifCarrotson wrote:
| A couple things:
|
| 1. On Windows and Linux, devices have to handle a huge number
| of hardware configurations. Not everything can go into the same
| "deep sleep" mode with the same instructions, so developers
| implement different "idle" states that may or may not discharge
| the battery quickly. Too many sales efforts focus on making a
| laptop 'boot' from idle in seconds, and too few focus on making
| it usable after being off for days. Look up "S3 Deep Sleep",
| "Modern Standby", and the bevy of options described at
| https://learn.microsoft.com/en-us/windows-hardware/drivers/k...
| to learn more. Apple only supports a small list of hardware
| platforms, and can make deep sleep work and resume quickly and
| reliably on just that list. Even the Kindle Fire is not totally
| vertically integrated between the MediaTek processor and
| Android OS and Amazon UI, there's bound to have been a lot of
| finger-pointing and little leadership pushing for microamp-
| level sleep capabilities.
|
| 2. Android/Windows/Linux allow users to install applications
| that do things that consume battery in the background - for
| example, my Tile bluetooth locators and Garmin smartwatch work
| great with my Android phones. They wake up a sleeping phone and
| force it to use a little power to grab a location data point or
| send my watch an updated weather forecast. Apple doesn't let
| third-party developers do the same.
|
| I'd bet that if you pushed and held the power button on your
| Kindle tablet on Sunday night for 3 seconds and chose a full
| "Shut Down", and then held the button again Friday for 2
| seconds, it would have the same battery level as it had when
| you turned it off. It's just because it's been checking for
| system/app updates and otherwise running code while 'sleeping'
| unused that the batteries are low, in spite of the fact that no
| humans were using it.
| Dalewyn wrote:
| I always just shut down my Windows/Linux machines, sleep in
| all its forms has never worked properly. It's far better for
| my sanity to just turn it off knowing I can just turn it back
| on.
|
| Especially in this day and age of blazing fast (read: several
| gigabytes per second) SSDs, cold boot speed for most people
| is a non-issue.
| superjan wrote:
| I set my laptops to hibernate when the lid closes. Entire
| RAM written to disk, then a full powerdown. Do turn off
| wake timers and wake on USB (sometimes disabled in true
| hibernation but not always).
| franl wrote:
| Is it even possible to fully turn off a Kindle anymore? I
| want to do exactly what you're saying to prevent the draining
| of the battery, but the only options that appear after
| holding the power button are "Cancel" "Restart" and "Screen
| Off". Holding the power button longer just seems to restart
| the device :/
| cma wrote:
| I they need them always on so that they can gather up data
| from Amazon smart TVs that were never connected to the
| internet (project Sidewalk).
| lern_too_spel wrote:
| Previously discussed:
| https://news.ycombinator.com/item?id=34582931
| hedora wrote:
| 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 wrote:
| 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 wrote:
| 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.
| TheSpiceIsLife wrote:
| * * *
| NickBusey wrote:
| This sounds like a small tweak in the manufacturing process that
| could lead to potentially very large gains down the road.
| Fantastic work!
| giuliomagnifico wrote:
| 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).
| kazinator wrote:
| 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 wrote:
| 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.
| abracadaniel wrote:
| 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.
| supernova87a wrote:
| 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...
| Maursault wrote:
| Either your batteries were old[1], or you're overlooking
| something else that might have caused increased self-discharge,
| such as high humidity.
|
| [1] https://www.mcgill.ca/oss/article/general-science-you-
| asked/...
| chrismeller wrote:
| In my first job we had several UPSes for racks of equipment
| that had been augmented with marine batteries for longer life
| and all the batteries were on slats of wood to keep them off
| the floor.
|
| I asked and got the same answer you did - they will last longer
| - but I've never understood _why_.
| slug wrote:
| 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 wrote:
| That's what I would have thought as well.
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(page generated 2023-01-31 23:00 UTC)