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Report proper battery life estimates on laptops System
Many iBook and PowerBook owners have been complaining that the battery meter is under-reporting the battery life. Here is how you can force the OS to recalculate the battery life for the better:
  1. Follow the previous hints (1, 2, 3) as already recommened (drain your battery fully then recharge, turn off airport etc).
  2. Leave your laptop plugged in for a while, even after 100% charge (don't know if this step is necessary, but thats what I did).
  3. Before you unplug your laptop to take on the road, turn the screen brightness all the way down to the last visible level.
  4. Close the lid and let your laptop go to sleep. (or do it from the Apple menu). Unplug your laptop.
  5. When you wake your laptop, do not turn up the screen brightness yet. Wait until the battery icon stops "(Calculating...)"
  6. Wait a few more seconds to let the reported time stabilize.
  7. Turn up the screen brightness to a comfortable level and work.
On my iBook 700, the first time-left report says 5:07 when I do this! Then as I turn up my screen brightness all the way I get a stable report of 3:30. This is much better than before.

Basically the idea is to make the battery calculation occur when the laptop is consuming the least amount of power.
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Report proper battery life estimates on laptops | 9 comments | Create New Account
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Report proper battery life estimates on laptops
Authored by: JoeGrind on Apr 02, '03 11:07:53AM

This hint makes it sound as if when my powerbook "calculates" remaining battery time, whatever it comes up with, is how long it runs for. Is that the case? Did you actually time your running time to be certain this helped?

I was under the impression that the remaining battery time is just an estimation based on how much battery capacity you have left and the rate at which you are currently using the battery. It then runs for as long as you have charge left in the battery, no matter what it originally "calculated" it to be.

This clearly has a great deal of bearing on this hint. Logically, I'd go with the second option, but anyone know for certain?



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Report proper battery life estimates on laptops
Authored by: MattHaffner on Apr 02, '03 12:07:38PM

Well, from my experience last night, after surfing around for a few hours doing low CPU & disk tasks and then installing the QT 6.1.1 update with <15 minutes reported left, I'm pretty confident that the estimate updated in real time. The 'minutes' clicked down much faster than real time.

Anecdotally, I could swear that I've seen the estimate start very low and then ramp up and add an hour after a minute or two of doing nothing.

I really can't imagine that this is based on a single snapshot when you bring it out of sleep. It does need a baseline to give you any estimate at all though, so that's why the 'Calculating...' appears--it has no history to draw from yet.



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Report proper battery life estimates on laptops
Authored by: JamieD on Apr 02, '03 01:43:03PM

I believe the initial calculation is an important parameter in the continual calculation the meter does. It is as if there is an integrator in the algorithm. The idea is that you start off on the best possible value to begin with that way you maximize the amount of time that is reported.

With this method I get at least an extra 45 minutes (actual time) out of my iBook before it tells me it needs to go to sleep.



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Necessity of Previous Hints?
Authored by: Enkerli on Apr 02, '03 12:48:52PM

There's been several posts on battery life lately, but what's the bottom line? Is draining-and-recharging really necessary? With current [i,Power]Books? What should we expect from, say, a one-year-old battery?
(I rarely use my iBook on battery for extended periods of work)



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Necessity of Previous Hints?
Authored by: JamieD on Apr 02, '03 02:12:13PM

No one really knows. But Apple has put out a knowledgebase article (http://docs.info.apple.com/article.html?artnum=86284) that suggests you should try it.



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Necessity of Previous Hints?
Authored by: Tom Robinson on Apr 02, '03 02:22:27PM

According to BatteryUniversity, you should avoid a full discharge cycle with Li-ion (as found in newer Powerbooks) as overall battery capacity is reduced.

The whole site makes interesting reading and there's a summary table at http://www.batteryuniversity.com/partone-21.htm.

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Necessity of Previous Hints?
Authored by: JamieD on Apr 02, '03 02:50:54PM

Very true. This is not something that should be done regularly. But if it helps to do it once in a blue moon you are going to gain more than lose.



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Necessity of Previous Hints?
Authored by: Accura on Apr 03, '03 08:24:28AM

how do you know when your at that point of greater gain than loss?

---
"The time has come," the walrus said. "To talk of many things..."



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Batt.Bash
Authored by: tgermer on Apr 02, '03 11:56:55PM

I tried this last night and now when I running the batt.bash script that was recently posted here it says my capacity is 4231. Where before I did the battery drain it was 4285. Weird.



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