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

Post by singlow » Mon, May 04, 2015, 9:36 PM UTC

seanp2k2 wrote: post #66

singlow wrote: post #54

I know that this was an issue on my ThinkPad W700 with Linux installed. In Windows, the Lenovo drivers would automatically manage the charging level to preserve battery life, but in Linux it would overheat when plugged in for extended periods of time, and I suspect that it was "over-charging". Within a year, the battery had about 50% capacity, and a replacement battery degraded as quickly. My current ThinkPad w540 do…

I'm pretty sure that the charging logic is built into the battery or other dedicated charging circuit hardware. Almost positive that while the OS can say "don't give power to the battery", it can't say "give power to the battery even though the battery says no". Not a great source, but this agrees: http://computer.howstuffworks.com/laptop-battery-overcharged...

Post by sown » Mon, May 04, 2015, 9:37 PM UTC

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".

    upower -i /org/freedesktop/UPower/devices/battery_BAT1 | grep capacity | awk '{print $2}'

    upower -e

Post by eertami » Mon, May 04, 2015, 9:39 PM UTC

chx wrote: post #194

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%…

On Linux and ThinkPads you can use acpi_call to set these tresholds https://wiki.archlinux.org/index.php/Tp_smapi#2nd_Option (the old tp_smapi way ceased to work about four years ago).

Post by barrkel » Mon, May 04, 2015, 9:46 PM UTC

JoshGlazebrook wrote: post #125

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".

Is your machine even operational? My macbook air from 2011 (with Yosemite) is sluggish to the point of being unbearable to use and just collects dust.

Post by mc32 » Mon, May 04, 2015, 9:49 PM UTC

geoelectric wrote: post #177

mc32 wrote: post #168

Earlier quoted context omitted.

It'd be nice if the battery controller/charger had the intelligence to make these optimizations transparent to the end user. So present them with 100% or whatever, but in actuality, the battery is at 90%, most of the time it's plugged in, and so on.

I thought this was actually standard operating procedure for laptop batteries (or really, anything using lithium batteries). Similarly, 0% is actually more like 5 or 10%. If you actually deep discharge a lithium battery to 0%, think they'll sometimes have problems taking a charge again. You see this occasionally when someone has taken to 0% on the meter, then let it self-discharge on the desk for a long time.