What things effect battery life? and by how much

Ok if anyone has any clues on this it would be something great to know. Lets say everything is the same on a laptop except the one thing.

If its the screen obvioulsy smaller is gonna use less energy, but any guesses at to the difference from 15 to 14 inches, 14 - 13, and so on? I know something like that is a tough comparison to make cause most places drastically change the configurations as screen sizes change. What about LED vs CCF, LEDs are suppose to save energy but any approximation as to how much? That one is probably a fire starter cause in some reviews I read they said certain LEDs didn't save any power in some laptops and others were better.

I know a ssd saves off a hdd and a slower speed hdd saves off a faster one and a smaller one saves off a larger one, so in this case there are even more variables, but is there anywhere out there with a chart or something with reasonable, educated guesses, if not actual figures, as to the differences?

When it comes to a processor obviously speed makes a difference, but if the speeds are the same what about amount of cache, would 6 save over 4 and 4 over 2 or the other way around? If I recall what I read somewhere a larger cache takes more energy which makes sense, but when in use does it save energy from being spent elsewhere?

I'm sure there are other things I'm not thinking of, and there are others i didnt mention like more ram obviously saves energy as the hdd doesnt have to spin up as often and can cache more things into ram for use. I know as technology changes these things change but I would assume these would be some good things to know if looking for longer battery life in a laptop and thought maybe a discussion about them would be good.

 

Screen size is probably #1 in terms of power consumption, next being the GPU, then CPU, chipset, screen backlight, HDD, and finally memory. While there are many variations, good LEDs and good SSDs will always be better than good CCFLs and good HDDs, due to their solid state technology. Cache plays more of a factor than CPU speed IMO but the differences aren't much.

 

I already know what you said is true, like I said in my original post. I was curios as to much more specific figures or at least as specific as anyone can provide.

 

don't forget overheating and/or freezing your battery. That stuff can easily cause permanant damage.

 

Check up Intel's spec sheets and read reviews with power consumption measurements. Intel's PM45 motherboard is rated 9.5W (7W for the chipset and 2.5W for ICH9 controller), GM45 adds 5W for the 4500MHD integrated GPU.

The link in my sig has the typical TDP for most of the current GPUs, though I haven't updated it in a while due to rarity of many of the new GPUs. The power consumption of GPUs can vary quite a bit in terms of idle and actual maximum draw however, so take the figures with a grain of salt.

Most of the CPUs, despite their different TDP, have similar idle power consumption, maybe a difference of 0.5 to 1W.

In the Lenovo forum, jonlumpkin estimated that going from a 12" to 14" (both WXGA+ LED w/ comparable brightness) screen differ by about 0.5 to 1.5W.

SSDs can be as low as 0.06W on idle and 0.15W on load according to Intel, compared to WD's 500GB Scorpio Blue HDD's 0.85/2.5W on idle/load.

DDR2 and DDR3 SO-DIMMs both use only a fraction of a W in terms of power, around 0.25W.

Hope this helps.

 

Thats the kind of information I was looking to get, hopefully some more people will pipe in with some more figures as well. thanks

 

I guess the biggest thing will be the software you run, for instance my notebook under VHP32 seems to idle using ~12W of battery power with the LCD turned off and using an external monitor. If I run IntelBurnTestV2 that figure shoots up to ~52W.

FWIW my 14.1" 1280x800 LCD is quoted in HP's manual as 4W, the battery power to run it seems to be at ~2.6W with brightness at 0% (that's not a black screen BTW) and ~6.3W at 100% brightness.

sgogeta4, not sure where your getting 0.25W for DDR2 from AFAIK a typical 2GB PC2-6400 SO-DIMM will use ~1.5W operating power per module.

 

I got it from a Samsung engineering paper stating their DDR2 SODIMM modules consume no more than 400mW. Where did you get your 1.5W?

 

Have a look at this, see what you think.

http://www.valueram.com/datasheets/KVR800D2S6_2G.pdf

Seems other modules are similar and although I dont have an average for Elpida modules, they quote a max of 8W which seems quite high if they are only going to run at sub 1W.

 

That's pretty high, I don't see that being correct. I mean if your notebook only draws 10W at idle (like an ultraportable) when you have 2 sticks, if you take 1 stick out then the power should drop to 9W (unless your values aren't for idle, on load it's a different story). But still, the battery life would change significantly for that notebook (on a 40WHr battery, you should gain almostt 30 min more battery), but in real life testing, it doesn't. Hence why I don't believe that a stick of memory would take that much power.

 

I'm not sure how much the RAM is being used when the notebook is idle vs cache or exactly how they base their power calculations and I agree, 3W for RAM while idling at 12W (no primary LCD) does seem a lot. Do you have a link to the Samsung data, I'd be interested in reading it.

 

It was here a while ago, but I can't seem to find it now. I'm sure it's somewhere on the Samsung site but I haven't done a thorough search. I believe from the sheet, the more chips (obviously) take more power, but it's not enough to be significant in most notebooks. A 1GB stick vs. 2x4GB stick in an ultraportable, might show noticeable results (maybe up to 10 min more battery life, but rather insignificant in the bigger picture).

http://forums.appleinsider.com/showthread.php?t=66522