Why don't laptops have a "small battery reserve"?

For example, if you wanted to take out your battery, you could still have a small battery (that has priority charging over the main battery) inside that could power your laptop for ~5 minutes so that you can change the battery; and this wouldn't just be useful for when the laptop is already on: sleep and even hibernate uses power, so if you want to change the battery during sleep/hibernate, or perhaps are only using an AC source and want to sleep/hibernate and then leave the AC source, the resume data would be lost: a reserve battery could preserve that data

 

Hibernate does not use power. So to change battery, just hibernate the laptop, change the battery, then turn on the computer to resume your work.

 

Yeah, hibernation saves everything to the hard drive.

Good idea though, I see where youre coming from...as to why they dont, probably because of cost cutting and lack of space.

 

It is another battery with another circuit and more space in the laptop. In other words...with the race to the bottom on cost that is an expensive idea.

 

im pretty sure hibernate uses power, i read it somewhere, i think a computer can stay in hibernate for months or something, i believe that if you hibernate and take the battery out, you'll have to do a cold boot, i can't really remember, but i believe i recall trying this before

edit: lol comma power

 

W7 (and maybe Vista) does use a little system power in hibernate, but that is only because it keeps the RAM and running much like sleep did with XP. The same contents of RAM are stored in the hard drive though if power is cut.

That way it is quicker to resume most of the time, but even if power is completely cut you are still okay. (If I remember correctly...)

 

Yeah, in either case hibernation is stored on the HDD...sleep mode is all RAM and will have to be cold booted if power cuts out.

 

I don't think so - I think you have it reversed. In desktops, the default behavior in Vista (and possibly Win7 as well, not sure) when the computer is put in Sleep was for it to copy the RAM contents to the hard drive as well, so that if power is lost, the data still persists. So, it takes as long as Hibernate to go to Sleep, but it comes out of Sleep much faster, provided that power is not cut. That behavior can be disabled though.

Hibernate does not use power in most senses (of course, the internal clock still uses power, but that's from the small button battery on the motherboard) - all the components that are off when the computer is Shut Down are off in Hibernate as well. The only difference is that during the boot procedure, the computer detects the data stored in the hibernation file and copies this data back to RAM.

 

That's what I get for not using hibernate or sleep on my systems for quite a while .

 

Vista has hybrid sleep. It saves opened programs and documents into the HD in case of a power cut

As for the reserve battery, its not worth it just for the benefits of battery hotswapping

 

Hibernate doesn't require any power. I've done it and removed the battery and resumed hibernation after just fine.

 

ahh i must be wrong then, thanks for confirming

 

You know, I recall the 2003 era iBooks having a feature like this, although I don't think you had much more than a minute to change out the battery.

 

Hot swappable batteries can be used with very few laptops.

Motion Computing has some if I remember correctly.
They make only tablets though (the ones in Stargate Atlantis for example).

 

lol hibernation is enough and seriously with laptops being heavy already , extra weight and cost not needed.