Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Charging a lithium battery to 80% only?

electronics.stackexchange.com

Post reply on HN
Print view View original

211–220 of 362 posts

Re: Charging a lithium battery to 80% only?

#211

Post by bayindirh »

codedokode wrote: post #208
bayindirh wrote: post #148

Earlier quoted context omitted.

IBM Thinkpads have "cap charge at n%" setting since 1999 or something, but it's not smart. You set it. It was also present in HP and Dell's business notebooks for quite some time, but again, it's not smart. Just a pre-defined percentage. Apple manages maximum charge capacity automatically depending on the way you use your computer.

> Apple manages maximum charge capacity automatically depending on the way you use your computer. Apple cannot predict where you are going to use laptop on AC power at home or whether you are going somewhere and need a full charge. So manual control is better.

There are apps for that if you want, and if it enables hold-off, you can always say "No, I need full charge now, so please charge".

Re: Charging a lithium battery to 80% only?

#212

Post by xxs »

Charge Li-Ion to 4.21V and that's that. The rest (over 4.25) is overcharging. If you see the voltages charged - it's clearly outside the spec. Using a voltage -> percentage table is just a gimmick that has managed to stick. The entire discussion is littered with percentages that aside being non-scientific, mean absolutely nothing at all as they are not comparable.

Most tool batteries, vacuum and mower robots - all charge below 4.2V - yet phones (and some laptops) are special.

Morealso charging it to '80%' means little as we have no clue what charge profile: constant voltage [how high]/current is used and when.

Re: Charging a lithium battery to 80% only?

#213

Post by dghughes »

belltaco wrote: post #14

I wish they would label it so that it shows 100% charge when it's actually charged 80%, and then give an option to 'overcharge' a configurable amount till 125% (the current 100%). That way it will make people aware that they are reducing the battery life by overcharging, and be picky when they overcharge. But this won't happen because reduced battery life is a big direct and indirect(by reducing performance like Appl…

People that know about the 80% trick may then only charge it to 80% of the 80% which now shows 100% which would be 60% (if my morning fog brain is getting it right). But if they know it's actually only 80% when showing 100% they'll charge it to 100%. Then people will complain "they don't make phones like they used to".

Re: Charging a lithium battery to 80% only?

#214

Post by em-bee »

The_Colonel wrote: post #132
jader201 wrote: post #102

Earlier quoted context omitted.

If you leave it plugged in all the time, battery life doesn't matter. Self-limit or don't. I'm rarely away from a power source for very long (and when I am, I'm not on my phone much). So I just leave it plugged in all the time. I've very rarely had my battery die on me, and like OP, I leave mine plugged in all the time. At night or while working, it's charging. Even after a few years, I don't notice much of an impact…

> At night or while working, it's charging. It doesn't have to be charging all the time. Some laptops have "intelligent" detection of the "usually plugged-in" state and won't keep the battery charged 100% at every moment, but will allow dropping it somewhat before charging again. I suspect MacBooks are doing this quite aggressively (while lying about 100%), since their batteries tend to last (in terms of cycles) long…

i thought that if the battery is charged the device will simply ignore the battery and run directly from the wire. so a fully charged battery should not be affected at all. repeatedly dropping down and recharging sounds like a bad idea.

Re: Charging a lithium battery to 80% only?

#215

Post by aikinai »

glandium wrote: post #108
artimaeis wrote: post #16

Earlier quoted context omitted.

I just picked up my 2017 iPad Pro. It was last charged Nov 15. Been sitting by the bed mostly unused since. Currently at 80% charge. I haven’t experienced what you’re describing on an Apple device since they switched the laptops away from Intel chips. In my experience, the OS does matter. I can’t believe how bad the rest of the industry is at this. Amazon’s Kindle line is incredible at this IME, but those are pretty…

I have the exact opposite experience. My 2013 MBP can keep its charge for months while suspended/hibernated. My first-gen M1 MBA will deplete the battery in a week under the same conditions.

Does the latter have Power Nap enabled?

Re: Charging a lithium battery to 80% only?

#216

Post by matheusmoreira »

Arainach wrote: post #3

I've given up trying. If a device is willing to lie to me and only charge to 80% while saying it's charged, great, but all of this "try to stay in a range" logic flies in the face of reality. Every device I use besides my cell phone, Nintendo Switch, and Nintendo 3DS has atrocious power drain when not in use. OS does not matter. Windows laptop, Linux laptop, ChromeOS laptop, Android Tablet, Amazon Tablet, you name it…

I don't understand why devices can't switch to external power when plugged in. It's like they simultaneously charge and discharge the battery instead of bypassing it.

Re: Charging a lithium battery to 80% only?

#217

Post by rxyz »

osdril wrote: post #154

FYI, on Apple Silicon Apple included a firmware-level "hard-switch" to limit the charge to 75/80% only. It was discovered by marcan while working on Asahi and in my experience it's much more convenient than the built-in ML-based solution (and also less hacky and bloated than AlDente). See this discussion [0] on GitHub for the explanation and this snippet [1] for easy use. This solution also works while the laptop is…

this switch is available to users on iPhone 15's

Re: Charging a lithium battery to 80% only?

#218

Post by gwbas1c »

p1necone wrote: post #21
belltaco wrote: post #14

I wish they would label it so that it shows 100% charge when it's actually charged 80%, and then give an option to 'overcharge' a configurable amount till 125% (the current 100%). That way it will make people aware that they are reducing the battery life by overcharging, and be picky when they overcharge. But this won't happen because reduced battery life is a big direct and indirect(by reducing performance like Appl…

I'm pretty sure most (all?) manufacturers already do (the first part of) this. 100% can't be the point at which the battery literally stops taking new charge - if you did that they'd catch fire all the time. It's just that the manufacturers idea of what "100%" should be generally skews more towards the immediate battery life end of the tradeoff, whereas some users prefer to have "100%" closer to the maximizing long t…

I wish my Tesla did that

Re: Charging a lithium battery to 80% only?

#219

Post by The_Colonel »

em-bee wrote: post #214
The_Colonel wrote: post #132

Earlier quoted context omitted.

> At night or while working, it's charging. It doesn't have to be charging all the time. Some laptops have "intelligent" detection of the "usually plugged-in" state and won't keep the battery charged 100% at every moment, but will allow dropping it somewhat before charging again. I suspect MacBooks are doing this quite aggressively (while lying about 100%), since their batteries tend to last (in terms of cycles) long…

i thought that if the battery is charged the device will simply ignore the battery and run directly from the wire. so a fully charged battery should not be affected at all. repeatedly dropping down and recharging sounds like a bad idea.

Based on my limited understanding it's not that simple. At least some laptops still use battery power during power spikes even when plugged in.

> repeatedly dropping down and recharging sounds like a bad idea.

I noticed this with my Dell Precision machine that it dropped to 99% and then re-charged to 100%. It was plugged-in 24/7. You can normally configure this in BIOS, but it was locked in my computer by my employer. Unsurprisingly, the battery swelled within a year.

OTOH, I'm not sure how much more damaging this is, given that even just keeping the battery at 100% for long periods of time is damaging.

Re: Charging a lithium battery to 80% only?

#220

Post by negative_zero »

shmeeed wrote: post #203
negative_zero wrote: post #89

There is so much confusion, misinformation and naive testing about this topic. I've only learned about this "80% battery thing" when researching EVs recently and it seems to have been (maybe) spawned by the Nissan Leaf many years ago. And now it's appearing on HN seemingly once a week. What has changed? Is someone running an information(or disinformation) campaign? Blog or app to promote? I've not spoken earlier for…

Source?

14 years in electronic products (consumer and industrial) including Multi chemistry battery management system (BMS) designs.
Post reply on HN