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Ask HN: Should I unplug my laptop charger at 100%?

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Re: Ask HN: Should I unplug my laptop charger at 100%?

#131

Post by solve »

jerf wrote: post #8

As I sit and look at the replies already coming in, may I just add an enormous [citation needed] to the entire discussion? A question brought on by too many conflicting anecdotes can not be resolved by throwing another unsourced anecdote on the pile. (Incidentally, I'm at least a bit curious myself as to the answer, and have my own pile of conflicting anecdotes I've read.)

If I were running a social network like this, I'd post questions with definitive answers like this one, see who voted up / wrote the wrong answers, and then block those people from voting / commenting again for a long time period.

Do that enough times, and you'd quickly have the smartest site on the Internet.

This thread literally has people posting links to Yahoo Answers.

Re: Ask HN: Should I unplug my laptop charger at 100%?

#132

Post by [deleted] »

DavideNL wrote: post #107
bkanber wrote: post #58

Source: I have a master's degree in mechanical engineering in hybrid vehicle powertrains, and a big part of my research was battery technology. I spent some time working with the folks at National Semiconductor learning this, so I have several primary sources. Disclaimer: my knowledge of the field is from ca 2010. 1) Lots of deep discharge cycles do negatively affect battery life. Try not to jump between 0% and 100%…

That's nice to know. However, i'd rather buy a new battery after 5 years (if my laptop is still fit and the battery is dead), than having to complicate my life and think about when to unplug or charge my laptop multiple times each day for 5 years... My Macbook air from mid 2011 is currently at 100/6700*5629 = 84% battery health. (6700 = design capacity, gathered from "ioreg -l -n AppleSmartBattery -r".

[deleted]

Re: Ask HN: Should I unplug my laptop charger at 100%?

#133

Post by Guillaume86 »

sigmar wrote: post #114
bkanber wrote: post #58

Source: I have a master's degree in mechanical engineering in hybrid vehicle powertrains, and a big part of my research was battery technology. I spent some time working with the folks at National Semiconductor learning this, so I have several primary sources. Disclaimer: my knowledge of the field is from ca 2010. 1) Lots of deep discharge cycles do negatively affect battery life. Try not to jump between 0% and 100%…

>plug in and let charge to 90%, unplug and use for a couple of hours, plug back in at 50% or so, rinse and repeat. My thinkpad has a mode for keeping a healthy battery that stops charging at 90%, then trickle charges to keep it there (it also allows for fine tuning of this behavior)

Yes my Samsung Serie 7 (now Ativ Book 8 I think) has the same feature (stops charging at 80%) and I think my previous Sony Vaio also had something like that..

I use it on my Samsung given that I don't really need +5 hours without plugging anyway.

Re: Ask HN: Should I unplug my laptop charger at 100%?

#134

Post by bkanber »

shocks wrote: post #128
aqme28 wrote: post #121

Earlier quoted context omitted.

Why don't device manufacturers code this kind of thing into their power/battery drivers?

Is it possible they do, and the battery level indicator you're looking at is lying to you?

This is often the case. Not all the time, but lots of devices have started doing this.

Re: Ask HN: Should I unplug my laptop charger at 100%?

#135

Post by Osiris »

james-skemp wrote: post #117
Osiris wrote: post #100

I wrote a program that monitors battery state for Windows [1], and after a lot of research I concur with the other opinions posted here that leaving a lithium ion battery at 100% for long periods of time is not a good idea. The software I wrote has configurable alerts so a user can get an alert then it's reached a certain change level (like 90%) and then again when it drops below a certain level. Users have specifica…

Slightly OT, thanks for this software. When I picked up a new Windows tablet I was looking for a better battery indicator and found BatteryBar Pro. I don't personally use that feature, but it was something that I liked. The feature to show remaining battery and charge time is what I really enjoy about it.

I'm glad you've found it useful. Let me know if you have any suggestions or feedback.

Re: Ask HN: Should I unplug my laptop charger at 100%?

#136

Post by bkanber »

zobzu wrote: post #124
bkanber wrote: post #58

Source: I have a master's degree in mechanical engineering in hybrid vehicle powertrains, and a big part of my research was battery technology. I spent some time working with the folks at National Semiconductor learning this, so I have several primary sources. Disclaimer: my knowledge of the field is from ca 2010. 1) Lots of deep discharge cycles do negatively affect battery life. Try not to jump between 0% and 100%…

A lot of laptops allow for various trickle charging modes. Generally they stay charged between 90 and 100% (charges to 100 then wait until 90), some allow for charging to 80. In my experience there can be memory effects when fully capping at 80% over the years, though.

Li-ion batteries do not have a memory effect. LiFePO4 do, however.

Re: Ask HN: Should I unplug my laptop charger at 100%?

#137

Post by mangeletti »

Personal experience:

I'm on an early 2011 MacBook Pro (purchased in March, 2011), which I've used for about 8-10 hours per day, 5 days per week, since the date I purchased it. I have about 6.5 hours remaining at a 91% charge (screenshot for proof http://cl.ly/image/1a2d2y2V1J2O). I consider this to be pretty good for a notebook that has been used extensively for more than 4 years, which is why I felt like I should share my advice on keeping your battery healthy (I do exactly this, and have since day one, except when I'm mobile and actually use the battery - about 2 times per month - today is one of those days):

  1. keep your notebook plugged in all day while you work
  2. unplug your notebook when you power it off at night
  3. on Friday, unplug partway through the day, allowing the battery to drain to about 30% by EOD
  4. Monday morning, start back at step # 1
The bottom line is, run the charge down significantly 1 (or 2 max) times per week, and let it sit (over the weekend) without a full charge.

Re: Ask HN: Should I unplug my laptop charger at 100%?

#138

Post by Guillaume86 »

BorisMelnik wrote: post #122
bkanber wrote: post #58

Source: I have a master's degree in mechanical engineering in hybrid vehicle powertrains, and a big part of my research was battery technology. I spent some time working with the folks at National Semiconductor learning this, so I have several primary sources. Disclaimer: my knowledge of the field is from ca 2010. 1) Lots of deep discharge cycles do negatively affect battery life. Try not to jump between 0% and 100%…

Exceptional. Armed with this info, this will surely save me a ton of money over time, especially if I can get my employees to adopt this reasoning. I've been dying for this answer for years now.

Depending of the type of work your employees do, it might be frustrating. If you need CPU power you'll not get the full speed when unplugged.

Also unplugging/replugging is annoying, get a brand/model that already has the charging cap option and just ask to enable it.

Re: Ask HN: Should I unplug my laptop charger at 100%?

#139

Post by mcculley »

This is one of those interesting "mesofacts" that is related to how batteries used to work. It's similar to when well meaning people share anecdotes about car maintenance that were only true back when cars had carburetors. These are hard lessons learned that are not necessarily applicable today.

It's certainly true that the old nickel cadmium batteries were harmed by continuous charging. But nowadays with lithium ion batteries, lots of laptops, batteries, and chargers all have little microcontrollers on them that can be smart about charging and maximizing the lifetime of the battery. The short answer is that you should read the manual that came with your particular system and see what it advises.

Re: Ask HN: Should I unplug my laptop charger at 100%?

#140

Post by tertius »

bkanber wrote: post #119
DavideNL wrote: post #107

Earlier quoted context omitted.

That's nice to know. However, i'd rather buy a new battery after 5 years (if my laptop is still fit and the battery is dead), than having to complicate my life and think about when to unplug or charge my laptop multiple times each day for 5 years... My Macbook air from mid 2011 is currently at 100/6700*5629 = 84% battery health. (6700 = design capacity, gathered from "ioreg -l -n AppleSmartBattery -r".

Agreed. I do avoid leaving my laptop plugged in overnight, but I'm also not too careful about leaving it plugged in during the day. I'll often pop the charger out when I notice the battery at 100%, but I'm not going to lose sleep if I forget about it or operate slightly sub-optimally.

I have a Lenovo Yoga Pro 2, it's got an app that manages this for me. I turn on "conservation mode" and it keeps the charge at 55%-60%. The only negative here (and it would be there with doing it yourself) is that if I run out without the charger I'm essentially at 1/2 capacity.
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