battery plasmoid and remaining time..

Zack Rusin zack at
Thu May 14 22:52:51 CEST 2009

On Thursday 14 May 2009 07:27:33 Sebastian Kügler wrote:
> > if my battery is going bad, that's one thing and i deserve everything i
> > get with that. nothing will save me then. but point to a defective corner
> > case in hardware is not justification for anything. we're talking about
> > generally working batteries, aka 99.9%+ of our use cases here.
> Actually, that's not true. A battery (Li-Ion anyway) has this nasty memory
> effect that means that its capacity starts deteriorating from day one. So
> the total capacity changes all the time, if for most cases in a fairly
> linear fashion.

That makes no difference. The system reports last full charge. ("acpi -V" will 
show you the capacity and the actual full charge). Battery either is charged 
or not and that percentage can be computed pretty accurately because it 
depends on /hardware/ and that's guided by math, the number you're arguing for 
doesn't depend on the hardware it depends on the /user/. 
You can as well add a feature to the monitor that reports the feelings of the 
user "today we predicted that the battery will last 3:22 hours, but it lasted 
1:01 therefore you were likely watching more porn than usual hence you're 
probably having a great idea. we compute that your mood is : awesome".

> It's not made up, as far as I can see it's remaining capacity / current
> discharge rate. So it does tell you when your battery runs out if you keep
> doing what you're doing right now.
> Maybe a good point is to think about how we can make this more clear to the
> user.

I'd suggest prefixing that number with an icon of a dude going "3 hours... no, 
2 hours! no! 1:30! no 6 hours! oh, for gods sake, i give up" and then an 
animation of him throwin his hands up in the air. that'd pretty much express 
exactly what it's doin.

> 10% can mean anything from 5 minutes (a relatively worn out battery) to
> half an hour for most newer batteries out there. (Those are not even
> extreme cases.)

of course that's also what "2 hours left" can mean.

> My point is that it's accurate given the current context. For the question
> "Will I be able to finish watching this movie?" 

i'm not sure how you're watchin movies but i never seen anyone keep playin the 
movie while they check status of different parts of their laptops. in fact it's 
a little hard to do when you're playin a full screen movie. not that i'm sayin 
that you couldn't borrow a laptop from a friend, ssh-in, export X, start 
another plasma session on your friends laptop and check that applet there. all 
i'm sayin is that it's pretty unlikely people will be doin that.

in general they'll either stop the movie or put it in some small ass window in 
a corner and check stuff. so the question isn't "Will I be able to finish 
watching this movie?"  it's "for how long will i be able to check the 'time 
remaining applet'" and you're right, for that it's pretty accurate. 
unfortunately until we add the animation i proposed above to that dialog 
people are unlikely gonna be doin it for the entire time they're usin their 
laptops. they tend to do other things like unpause the movie, make it go full 
screen, browse the web, watch youtube, play games... in other words the same 
activities that they had to stop to check the 'time remaining' label.

you could average out the battery drain over the entire time the laptop has 
been unplugged without usin too much resources which could give you a pretty 
ok approximation of "time left at the current usage", but is that really worth 
it? if we only had like one of them "usability" folks to sort this shit out! 


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