That reminds me of the Mythbusters (where has that TV show gone?) episode where they busted the myth about keeping a lightbulb on vs turning it on and off.

I can't remember it exactly but I think they said that turning the light bulb on only used a fraction of a second worth of power. Therefore it is more efficient to turn the light bulb off when not in use. The only exception was fluorescent tubes which used about 23 seconds worth of power. Still though if you are out of the room for more than 23 seconds then it is more efficient to turn it off.

They should do one with computers.

Yeah, I think they (or someone else, and I don't care who so long as it's reliable) should.

I never thought turning normal bulbs used lots of energy, at all.

I knew flouros did, but thought it was far more than 23 seconds worth. I always thought it was 5 or ten minutes. Not too sure why, just a bit of a guess I suppose!

Older flouros did, more modern ones use much less =)

Left my macbook pro with full battery sleep for 4 days - not intentional, was stuck in hospital - came back to a flat battery - that is why I shut down, not sleep!

I assume it had managed to write the contents of memory to disk before it died??

Sorry to hear about the hospital trip by the way, I hope it was nothing too serious.

Even on my *counts* three year old MacBook, it only looses 1% or 2% if it's slept for a week...

Hmm. I'm sure you did, but you have calibrated the battery according to Apple's guidelines here, haven't you, Gav?

And like the others, I hope you're recovering from whatever prompted your visit to the ysbyty.

What makes Apple's batteries so different?

I've never had to calibrate a battery on any of the other laptops I've used over the years...

My 5 year old Acer gets run 99% of the time on mains. I've never calibrated the battery and when the odd occassion arises, where I need the battery, it still holds out for around 2.5 hours, which is what it managed when new.

Likewise, there were no such instructions for my new Toshiba Tecra, that makes 7-8 hours off of the battery that came with it. It sits in its cradle most of the week, gets run every now and then on battery at home...

I don't know, Dave.

All I know is it helps the system to know the actual capacity of a new battery, and ensures you get the best performance from the off.

Like Ben, I've never lost more than a few per cent battery life when the machine's left in sleep for two or three days. I have a 2006 model MBP, and I had to have a replacement battery, but this one can give me five hours of use (with wireless networking on, but in low profile mode with the screen dimmed).

Don't you know, they're washed in unicorn tears.

As Heather says, it's not the battery you're calibrating, but the computer's ability to accurately know how much charge is left.

Maybe Wintel PCs don't bother telling you how much charge is left in the battery so there's no need to calibrate. Or maybe they just don't care about being accurate.

I haven't noticed any problems with accuracy. The Tosh has never been calibrated, at least not since it was delivered... Maybe it is calibrated at the factory?

It seems to be fairly accurate, it says 7 hours and I ran it for about 5 hours and it was still showing 2 hours left...

Well your unicorn tears are obviously more effective than Apple's.

Before I type anything, I know this is a single incident and the batteries in question may have been at fault.

My mate bought a Dell before going to uni, about four years ago. After a nine months he was getting enough juice out of the battery to get past POST, and that was about it. He got a new battery and a similar thing happened after eight or nine months. He had it plugged in the mains most of the time, with the odd hour off when he came to lectures. When he got his third battery I told him to calibrate it every now and again, two and a half years later and his battery lift has only degraded by about 30 minutes, though we think that's as a result of Vista more than anything (he originally had XP).

As I said, the first two batteries may have been duff anyway, or the third could just be luck...

Battery calibration seems to be peculiar to the latest generation of batteries. The battery in my borthers Sony Ericson (I know it's not spelled correctly) C902 phone had very specific charging instructions for the first time it was done so it was calibrated properly.

Run till virtually dead.
Plug into charger and kepp and eye on it.
As soon as it recorded 100% charge unplug it.
According to the paperwork if you keep it plugged in after it hits 100% it will significantly overestimate how much charge it can hold so the charge indicator won't be accurate. Isn't advancing technology marvellous.

On the flip side to these...

My Samsung R610 told me it had 1.5 hours left.

3 hours later and it was still going... ^_^

I use it quite a lot on battery, and it manages to last a phenomenal amount of time on normal use. Saying that, there's no difference between dimming the screen, switching off wireless, running fewer programs (except for games) etc... Same as "performance" mode.