Laptop power consumtion.

[oshta]

Coupled with my other thread, im curous as to how much power an average laptop acctaully uses in normal use?
- Im planning to have a laptop to use occatiatally on a boat, and electricty is always short.
- Can anyone mesure how much current there laptop uses when charging or running off the mains?
- Also, are published battery run-times fairly accurate, or masivly optermistic? Also what sort of capacity are the batterys in laptops?


Daniel

[arthurleung]

Even in chargin mode, it should only use somewhere around 120W max. Of course different models have different power consumptions. If you use a desktop replacement laptop the figure will be closer to 200W exclude charging (if it happens to have a battery)

[Funkstar]

well my HP Pavilion dv1000 (dv1139ea to be exact) has a 85w power brick and thats powering a 14" widescreen, 2gb ram, and a centrino Pentium M 1.6.

Considdering the screen and processor are the two biggest drains on battery live i would say that getting one of the little Core Solo systems with a 12" screen would be the lowest power consumer.

EDIT: Just had a thought. What voltage are you able to provide a laptop on the boat? By bypassing the power brick you could gain some extra power efficiency. Power bricks aren't the greatest, they do heat up after all.

[oshta]

EDIT: Just had a thought. What voltage are you able to provide a laptop on the boat? By bypassing the power brick you could gain some extra power efficiency. Power bricks aren't the greatest, they do heat up after all.

The boat is wired at 24v, but we also have a 24v-to-12v voltage regulator to run the radio (car stereo) and varous car-type mobile phone chargers.
- And as i said, theres currently no 240v, so somthing would need to be done! Hence asking if there where any in-car chargers for laptops.
- Otherwise, i could get an adjustable voltage regular, and set the to the required voltage. (although i beleave alot of laptops use an AC supply)


I did a bit of digging around, and found the nominal capcitys/voltages of a load of replacment laptop battery packs, from which i calulated how much juice they hold (in watt hours)
- The average seams to be about 40, so if average battery life is about 1.5 hours, thats about 27ish watts average.
- My battery bank is made up of 4*110Ah 12v batterys, making a 220Ah 24v bank, which should nominaly hold 5280 Watt hours (or 5.2KwH)
- So it sounds like it should/might work...?

The fridge is my main other power-drain.
- That draws about 50watt, and runs about 1/3 of the time, so averages about 16 or so watts over the day....
- And the lights are 11watt each, and i usally have 3/2 on at a time, in the evening.

Ahh, all these number is melting my brain, even with excell doing all the work!


Daniel

[oshta]

Also, just to make it more fun, the whole lot is charged from a (20hp) steam engine, using an alternator driven of the prop-shaft! Which only kicks out about 10amps.
- So its not like i can just fire up a nice big 2L diesal and spin over a big 120amp alternator like the other boats can!!


Daniel

[Funkstar]

What kind of boat is it? Does sound like good fun

Have you thought about a tiny Epia based system? there are plenty of power units etc that are designed for use in a car.

http://www.linitx.com has a lot

[oshta]

Its a 58ft narrowboat, called emilyanne (linky to my site)
- My grandad had her build about 15 years ago.

I have had a look at the Epia SFF PC's, but i would really like a laptop that i could use for other things too, when im not on the boat.


Daniel

[Funkstar]

Very cool looking boat

hope you manage to figure something out with the laptop.

[GuruJockStrap]

My Dell Inspiron 630m uses a 65W power brick. That has to power:

Pentium M 1.73GHz
512MB RAM
40GB HD
14.1" Screen
DVD RW
Integrated Wireless

Hope its of some use.

[oshta]

Yeah, i guess if the powerbricks are only rated at say 65watt, thats got to be a maxamum.
- Even if thats the output, the goging to be 80% effecnt at least?


Daniel

[Funkstar]

I've had a quick look around, and can't see anything definative, but some of the power bicks i found (although they are significantly lower power than laptop units) were around 80% efficient and the ATX power supplies are 65% efficient.

Someone else might have a better idea, and some more research may also help, but it seams that the highter the power rating of the unit, the less efficient they are.

[GuruJockStrap]

I'd take a guess that the 65W power adapter is very efficent as it runs extremely cool. If it was running at 65% efficiency I'd expect it to feel a lot warmer to the touch than it actually is.

[Paranoid2000]

I see 35W usage with my (aging) Inspiron 8000 (1GHz PIII, 512MB RAM, 60GB disk, 15" 1600x1200 screen with a 70W power brick) measured using a Brennenstuhl socket power meter. DVD/CD access or wireless (via PC-card) usage did not appear to make any noticeable difference.

For laptop batteries though, expect them to die out in a couple of years regardless of whether you use them or not (see DansData: Hatin' on lithium ion for more details). A hamster-wheel powered mini generator would be a better investment...

[oshta]

A hamster-wheel powered mini generator would be a better investment...

Well we have 120w of solorpannels...

[Paranoid2000]

Well we have 120w of solorpannels...

You may need to increase those then - presumably that 120W is a "peak" figure achieved during midday sun with an overcast day maybe only giving 1/3-1/4 this level.

[oshta]

You may need to increase those then - presumably that 120W is a "peak" figure achieved during midday sun with an overcast day maybe only giving 1/3-1/4 this level.

Yeah yeah, on an average day they only kickout about 30, even if its sunny ive never seen over 80. But there only really just for fun.
- The main source of power is the alterantor driven of the engine/propshaft.