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

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111–120 of 249 posts

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

#111
post #106
post #47

Consider the cost of a replacement battery and if it's worth the subconcious mental strain this consideration places on you. In short, leave it in because it's not worth worrying about.

Assuming your computer has a replaceable battery, which is not the case always. Replacing a $80 battery is worth it to avoid stress, but replacing a $2000 ultrabook may not be.

I would think your ultrabook would be past its manufacturer's warranty anyway at that point anyway and would be a candidate for some sort of DIY battery replacement.

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

#112
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.)

This is my favorite technology superstition, some citation would help many people sleep easier it seems.

It's difficult to argue the idea that any manufacturer of a device containing a battery cell would not engineer the system for the proper balance of longevity, capacity, and durability to result in acceptable quality to customers.

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

#113
post #77
post #20

Earlier quoted context omitted.

> If you leave it plugged in, you aren't losing cycles Too bad that some batteries wear out even faster this way because of the heat.

Why would there be extra heat if the battery is fully charged? Shouldn't a well designed charge circuit disconnect once the battery hits 100%?

Emphasis on "well designed". The 500€ laptops I've experienced in the past weren't and you could murder the battery like this in couple months, no matter the brand (HP, Dell).

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

#114
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)

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

#115
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%…

So what my laptop should do automatically is to stop charging once it hits ~90%, and start charging again when it hits ~40%. And the OS should give me an easy-to-reach option to "charge to 100%" for when I'm about to make a trip. Why hasn't anyone implemented this yet?

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

#116
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%…

[deleted]

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

#117
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.

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

#118
post #106
post #47

Consider the cost of a replacement battery and if it's worth the subconcious mental strain this consideration places on you. In short, leave it in because it's not worth worrying about.

Assuming your computer has a replaceable battery, which is not the case always. Replacing a $80 battery is worth it to avoid stress, but replacing a $2000 ultrabook may not be.

Even if it's not made to be user-replaceable, surely it can be replaced by someone with the right skills and tools for much less than the full replacement cost of the entire device.

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

#119
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".

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.

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

#120
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".

I agree with you. Instead of optimizing for battery life by constantly checking & adjusting my charging, I'd rather live my life focusing on other things. What I do is super simple: plug it in whenever possible.
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