First, I still think there is a good argument for percentage as a useful
statistic because your time remaining is a function of what you're using
your computer for (gaming/video editing/flash vs word processing), while
the percentage is not. Granted, users are going to make very rough
estimates, but eh.  As I said in my prior post, I think that both
statistics are more useful when you can access both of them.

>From what I've gathered, the most important factor in maintaining
battery health is temperature. High temperature = bad. Kind of hard to
fix in software though.

This table summarizes a bunch of does and don'ts. Almost all laptop
batteries these days are Lithium Ion batteries.
http://batteryuniversity.com/learn/article/do_and_dont_battery_table

When you store a battery, it unavoidably loses some capacity (not 
charge--capacity, ie, your battery used to store 1000 mAh, now only stores 800 
mAh overall effect is that your 100% charged battery doesn't last as long). You 
can reduce this effect by storing batteries at about 40% discharge (ie, charge 
to 100%, discharge to 40%, store). This table compares battery storage at 100% 
and at 40%: http://batteryuniversity.com/learn/article/how_to_store_batteries
Also here is a nice picture illustrating capacity loss: 
http://batteryuniversity.com/learn/article/capacity_loss

Old batteries like Nickle Cadnium had a "memory effect" where the
battery would "forget" how much capacity it actually had unless you
fully dischared it and then fully recharged it. Lithium Ion batteries DO
NOT have this behavior, and it is generally better for the battery to
AVOID a full discharge. This is because repeated partial discharges of
the battery increase the total number of charge cycles. Practically
speaking this means you want to start charging the battery when it's at
20-30% instead of at zero. This page has a table summarizing the result:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

The references I've used here are from batteryuniviersity.com because their 
site has nice sections and I can link you to specific things. Here are some 
more sources that give good overviews of how to maximize battery life: 
http://www.mpoweruk.com/life.htm (this goes into some of the chemistry of 
batteries)
http://forum.notebookreview.com/hardware-components-aftermarket-upgrades/91846-notebook-battery-guide.html#post1696318
 (A good practical guide, though he recommends monthly full discharges to 
calibrate the battery which is not good practice with lithium ion batteries)
http://en.wikipedia.org/wiki/Lithium-ion_battery#Prolonging_battery_pack_life 
(of course Wikipedia has something to say)

I hope this is helpful. Have a nice day.

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https://bugs.launchpad.net/bugs/811777

Title:
  Battery meter design needs to make both percentage and time statistics
  easily accessible.

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