At the very least, this looks cool.
Jeremy

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the flurry screensaver is great in the 'inverse'

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I Am Not A Display Engineer, But...

My understanding was that LCDs require power to go opaque. Thus, switching to black-on-white would take *more* power than normal white on black. However I base that knowledge only on a very basic understanding of LCDs mentioned briefly in Physics last year. (Something along the lines of, "This is an LCD. When you put current through it the crystal lattice twists. It polarizes light through a full 90 degrees, so no light gets through. So it's dark. Moving right along...") Real life LCDs might be completely different for all I know.

In any case, I definitely can't argue with the numbers. I'll try it; my TiBook's battery isn't what it used to be. Thanks for the tip!

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You're thinking of a simple LCD like one you'd find in a watch or calculator. And you are correct. In order to display that black bar a current is required. But the color LCDs used in laptops, are black by default. So the more black on the screen the less energy that would technically be required.

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Yeah, he may be thinking of the old Powerbook 1xx series. I had a 170 and bugged the guy who wrote the Basic Black screensaver to add a 'white' mode for Powerbook users. It make maybe 10 minutes difference on battery.

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It depends on how the polarizers are set. In a pocket calculator, you can invert the display by simply reversing the polarizing filter in front of the LCD

I got a reminder of this last week when I was servicing an LCD data projector and got one of the polarizers installed backward in the light engine...!

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I just inverted the screen, and if this hint were entitled "How to make things more readable in direct sunlight" it would still be a great hint, even if it increased battery consumption.

I've also made dark blue and black plain backgrounds with ordinary displays and this makes them much easier on the eye. This is especially important with CRTs, which before flat pannel LCDs came along, gave me migranes. My SGIs have black backgrounds, grey xterms and white type.

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I used to do this but once I thought about it I couldn't understand how it prolongs battery life. The screen is lit by a fluro-tube and inverting the colour scheme doesn't lessen the fluro drain on power. Well I don't understand how lighting a black pixel is going to take less power than lighting a white pixel.

On the contrary, inverting the colour scheme works the processor/GPU a little harder (just try watching a movie on a low end system with the colours flipped). Though I guess your results speak for them self - perhaps I'm wrong.

To get the best run out of a battery I set the brightness to as dim as possible, run as few apps as possible (saves CPU cycles and writing/reading to/from the swap file) and turn off the airport & bluetooth.

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I have to wonder if the poster actually timed this and had an improvement or just watched the battery life indicator as robg mentioned.

I'm pretty sure that the LCD backlight uses more power than the LCD itself. Therefore, dimming the display is the easiest way to get a real improvement in battery life.

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i have a 5 month old ibook and when i turn the brighness down my battery goes from 3 hours to 6 hours based on that alone

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I've always thought of that shortcut as the one that turns on Bizarro-vision!

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White on black often is easier to read, but (or is this just me?) the anti-aliasing/smoothing is awful compared to 'real' white on black without using the inverted color mode.. making it all hard to read.

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Yes, that's right, because sub-pixel anti-aliasing for TFT displays requires R-G-B oriented left to right, so reversing the colors is no good. I find that type in inverted color looks better if you (1) switch also to greyscale (in System Prefs > Universal Access), and/or (2) change the font smoothing style (in System Prefs > Appearance) to Standard, which turns off sub-pixel anti-aliasing.

Method 2 does not take effect immediately; you have to quit & relaunch apps. This makes it easy to compare the results, actually. Type some text in one app, change the setting, launch another app, paste, and compare them side by side. I find that Standard smoothing makes a slightly softer look, which I prefer for white-on-black. Just switching to greyscale (method 1) looks a bit sharper.

Both of these require a visit to System Prefs, since there are no keyboard shortcuts for them. Unless somebody can chime in with another method …

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While it is true that you cannot guarantee that any specific color will use less power in ANY LCD, it is fairly safe to assume that BLACK reduces power consumption in MOST laptop and computer LCD monitors.

It all depends on how the LCD is built.

I ran into this discussion - coincidentally - just a couple days ago in relation to the iPod and photoshop someone had done of a black iPod with black interface. A couple hours of looking into it, I found that I could not guarantee with certainty what would save power on any individual LCD.

The consensus, however, seems to be that the iPod has "white" as the default "off" color, and monitors use "black" as the default "off" color.

The reason the "off" color will save power, even though the backlight is still on, is because each pixel consumes power to allow light through. In the "off" color the pixel is not consuming any electricity.

When you want to use a different color, the pixel has to consume power - which causes the crystal to either rotate or straighten out (depending on the type of LCD). There are three crystals per pixel (rgb) and all three have to have power applied to make a color.

So the more pixels that are set in the "off" color, the fewer pixels that are consuming electricity.

My 15inch laptop is 1280x854 which is 1,093,120 pixels or 3,279,360 crystals. Each one consumes power in any color except black.

For more information about how LCDs consume power (other than the backlight) check out HowStuffWorks.com

How LCDs Work

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If turning the pixels off means longer battery life, then in addition to inverting the display, switching to grayscale and increasing contrast should improve results: fewer pixels will be lit with these settings.

Pure speculation, but it follows from the reasoning of the parent post.

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Have you tried refreshing your battery to increase the time it will last? It may not work but it did on a PC laptop I was brielfy forced to endure (and the PC had a similar type of battery). Here is what I did:
Let the battery run all the way down and put the computer to sleep automatically. Don't let it sleep/hibernate whatever until it does so itself due to low battery power.
Close the lid after this has happened to keep things shut down and plug in to begin charging the battery. Don't use the computer or open the lid until the battery is fully charged.
You SHOULD see an increase in battery time after this. Not sure how much but it should be more than a one time increase. It was in my case.

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Have you tried refreshing your battery to increase the time it will last?

Thus perpetuating the Memory Effect Myth.

Please, don't do this. It's not needed. You're not helping the battery to do this: in fact, you're just burning up one more cycle towards battery death.

All you might achieve doing this is an apparent recalibration of the computation "time to battery drained" parameters, but it's not going to affect the actual battery one bit (except burning one more cycle).

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Be sure and read Apple's tips on how to maintain your battery:

http://www.apple.com/batteries/notebooks.html

I've 'boosted' my battery capacity by doing the recommended Apple routine. My battery will go from 77% down to about 73% of it's original capacity. If I discharge completely and recharge, then I can get it back up to 77% again.

I'm getting these readings using Coconut Battery:

http://www.coconut-flavour.com/coconutbattery/

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I use custom system icons (Smoothicons from IconFactory) and this hint makes my iDisk look like a basketball.

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Dimming the display seems like a better option to me.

Another power conservation tip: when you can use an ethernet cable instead of WiFi. I get an extra 30 minutes out of my battery when I don't use WiFi on my 1 Ghz iBook.

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I have no idea if this is relevant at all, but in the old days when video RAM was scarce, setting the screen to B & W or 16 grey scale would give a noticable increase in performance over using thousands or millions of colors in the first color Macs and we did this on all of the ones used as servers. So perhaps the power savings has something to do with the fewer number of calculations needed to be performed by the CPU to create the colors? If so maybe this might help laptop batter consumption when colors aren't critical like when wordprocessing.

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Not likely. OS X uses 32-bit color internally. Rendering out to a lower bit depth actually requires more CPU (and possibly RAM; this detail I don't know) to calculate. Contrast adjustments, on the other hand, appear to be done in the GPU as gamma curves, which are "free".

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Although it might have been mentioned before, here are some additional tips, use all these for MAXIMUM PERFORMANCE (of battery that is)

•Turn off bluetooth
•Turn off 802.11 Wireless
•Turn off any extra internet interfaces you have: modem, ether, etc
•Turn off/Mute your sound
• Dim your display as low as you can tollerate
•Make sure there is no cd/dvd's in your computer.
•turn off backlighting on keyboard if you have.

This should squeeze every last usable second outta your batt. Hope that helps.

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AlMOST FORGOT:

•Set Processor speed to LOW (most new ibooks/powerbooks now have this feature in energy saver)

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I stopped trying to fix my bad laptop battery and finally just bought a new one. I got it from a website called www.laptopsforless.com and I love it. It works better than my original ever did and it was really affordable. If your tired of trying all the tricks of the trade and just a reliable and affordable battery I would check it out.

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