My Toshiba laptop consumes 20 Watts - go figure?

[MagicValleyHPV]

I'm genuinely surprised, figured at least 40-50w, but that's what my Watts-Up reads - tapped between the 120v AC power supply and the laptop - w/battery removed.

I was pondering the purchase of a more efficient laptop/netbook, but now, I'm not seeing much, if any, advantage in spending the $. My first choice would've been an Asus UL30A/UL30VT, after reading Notebookcheck's review. NC reports 4.4 / 7.6 / 8.8 Watts at idle, and 21.7 / 28.5 watts loaded - which is pretty amazing for a 13" screen. My A135 uses 19.7 / 20.5 watts average (it doesn't appear to make much difference loaded (web surfing & 80% screen brightness) or idle. I even DL'ed a HD scrubber prg just to load the hard drive and the wattage increased slightly to about 21.5. However, when I initiate standby, it drops to about .05w.

 My Toshiba A135-S4427
 Intel T2250 cpu
 2gb memory
 WD Black 7200 HD
 Alfa AWUS051NH USB wifi adapter.

[dbcollen]

You need to check the draw on the AC side of the adapter to get the whole picture, some power supplies have poor efficiency. Your AC draw may be twice as much.

[TomW]

My Sony Vaio E Series laptop uses 22 watts running. Checked at the AC input side.  Full battery.  No bluetooth yes wireless interweb.

Fairly recent laptop and not a hotrod by any means.

Tom

[MagicValleyHPV]

You need to check the draw on the AC side of the adapter to get the whole picture, some power supplies have poor efficiency. Your AC draw may be twice as much.

I'm not clear why I should test the AC PS because it's not even used in my off-grid system.  My only interest is actual DC consumption when the laptop is connected to my storage batteries.

[dbcollen]

You said the meter was connected to the dc side of the ac adapter. Must be a real neat off grid system you have there with a 19 volt battery bank.

[TomW]

I have 5 Sony Vaios of varying ages all have the same PS it is 19 volts.

I ain't willing to try it at 24 or 12. I have both sizes here. 12 for routers and wireless AccessPoints and 24 for my main system.

I just run it off the inverter with the AC adaptor.

Just from here.

Tom

[MagicValleyHPV]

You said the meter was connected to the dc side of the ac adapter. Must be a real neat off grid system you have there with a 19 volt battery bank.

As an initial test, it's now running off a single, Dewalt 28v lithium drill battery (pictured below). Notice the PCB on the right side of the image?  Now look at the watt meter in the second image - it shows the total load of BOTH the notebook and the DC-DC converter.  It's not clear to me yet why the amperage is now LESS than before, but it is.

[MagicValleyHPV]

Well duh!... The voltage is higher because it's now measuring at the 26v source. The wattage has increased slightly, as expected.  

[MagicValleyHPV]

My Sony Vaio E Series laptop uses 22 watts running. Checked at the AC input side.  Full battery.  No bluetooth yes wireless interweb.

Fairly recent laptop and not a hotrod by any means.

Tom

As you know, there are many variations between models given the variety of component options. Notebookcheck is one of the few review sites that measures notebook wattage. Not sure how they measure, but suspect DMM. Here is a sample E series Vaio they reviewed:

http://www.notebookcheck.net/Review-Sony-Vaio-VPC-EB1S1E-BJ-Notebook.27201.0.html

Quoting the review: "Intel's Core i5-430M together with ATI's Mobility Radeon HD 5650 provide for a medium energy consumption. Thus, the Vaio treats itself to between 48.1 and 69.7 watts under load. It's a significantly lower 16.8 to 23.8 watts in idle mode."

Why its wattage differs significantly from yours, I have no clue - again, possibility a differ machine all together, or some other variable.  And no, they do NOT measure the AC PS load - at least that's what the reader is led to believe.

[joestue]

@MagicValleyHPV, the current should be less, unless that's a linear regulator...

also, the current should decrease as the voltage delivered to the laptop is increased. however the watts will probably increase, the difference in power dumped entirely into the buck regulators, and thus wasted as heat.
if you decrease the voltage and the watts decrease, that would not supprise me either, and there's nothing wrong with running it at a reduced voltage permanently.

most laptops take that 18-21v and imediately convert it to just above the battery voltage. there's a dc-dc converter to charge the battery off that bus, and a dc-dc converter to run the processor, ram, 3.3v, 5v, 12v, etc. there's generally at least 7 of them or so.
its not uncommon to see a significantly reduced power draw by running the laptop off the batteries, with them directly connected to sometype of power supply. (be carefull with that, no short circuit protection...)

[MagicValleyHPV]

As with all loads, the core idea here is to minimize 'puter drain on my batteries. I had been shopping for a more efficient machine, assuming my Toshiba was a juice hog. Clearly it's not - considering it's a 15.4" display (at 80% brightness), and feeding a 'high power' wifi adapter while surfing. Still, I wonder how Notebookcheck measures their test machines. Most of the newer, high efficient netbooks they test, hover around 20w - bearing in mind, most have 12" or smaller displays and low consumption CPU's. Go figure?      

[MagicValleyHPV]

... most laptops take that 18-21v and imediately convert it to just above the battery voltage. there's a dc-dc converter to charge the battery off that bus, and a dc-dc converter to run the processor, ram, 3.3v, 5v, 12v, etc. there's generally at least 7 of them or so.

That's my assumption too, however, assuming I pipe directly into the laptop's battery terminals at the rated 10.9v, instead of feeding the 19v PS port, would I effectively bypass the charging circuit (in an attempt to reduce the load even more? I'm not inclined to try it, just curious.

[joestue]

i'd try it. btw, my laptop consumes 35 watts from the ac line, but only ~30 from the battery. a 44 watt hour cell lasts 1.5 hours  constant web surfing, about an hour playing a 2006-2008 era FPS game.
two hard drives, 2 ghz intel chip, and a graphics card. (yours is probably integrated)

[MagicValleyHPV]

joestue,

I've reconsidered tapping the OEM's battery terminals. However, I probably won't attempt it on the Toshiba.  Instead, I now have my hot little fingers on a freshly unwrapped Asus UL30A. Asus claims upwards of 12 hours on 5600mAh 8-cell pack - we shall see. Also, in my minimal research, I've uncovered one Ul30 user who has reported a scant 7 watts consumption on a tweaked Linux install during web surfing and prg usage. 

While it may, or may not yield a significant decrease in consumption, I plan to tap the OEM battery terminals on the UL30, if for no other reason, but to be able to employ the on-board battery monitoring software. Should be interesting.       

[dnix71]

Going directly to the battery may not be necessary. Intel Macs, which are just pc's now with OSX on them, will run off of less than the rated input voltage safely.

Apple never made a car charger for an Intel Mac, but they did make a cable you can take on a plane and tap the onboard 15v dc. The Apple laptop I have is supposed to have 16.5vdc at the tip of the charger, but the airplane adapter has no internal circuit, it just passes 15v directly to the input that normally expects 16.5v.

The result is, on a plane, you can use your laptop all you want, but it won't charge.

To save power on a laptop, you would disable the keyboard backlight, dim the display as much as you can stand, mute the audio, use only one ram chip if you can get by without adding one, swap out the hd for a SSD and not use any usb devices or external mouse or keyboard.

[taylorp035]

I have a Thinkpad W500.  Power usage varies from 8w to 35w.  It has a 15.4" screen, with a motherboard video card and a dedicated one.  I can go from 2.5 hours to 4 hours by going to the motherboard card.  I also have a 7200 rpm hard drive and 2 2gb ram chips.  72 Wh 9 cell battery.  I once got it to read 10 hours of remaining time.

Voltage while charging is 12.5, but the battery is only a 3s rated at 10.8v.

My old laptop was a Thinkpad T43.  With a 14" screen and a single core, it would use only 8-12 watts under conservative operation.  You could get it down to 6 watts if you were crafty.  With a modern and new $40 72 Wh battery from amazon, you can get 6-7 hours easy.  I have another T40 that the light burned out, and it is used as a DNS server.

Here is an older video of my laptop being powered from AA's.
http://www.youtube.com/watch?v=Isswvcz7Mcg

[dnix71]

Something else to consider. My Apple MacBook Pro has a battery charger that floats the battery. It charges and discharges in cycles. So if you have the charger hooked up it will show no power consumption at times and then jump up for a while. Overall, it averages about 20 watts. But this does have a dual core and external mouse. The charger is rated at 65 watts, and it's the lowest power version there was because this is the 13" display.

If you really want to go low, you probably need to get a cheap netbook. For $300 you don't get lots of ram, dual core or a wide screen.

[ChrisOlson]

My wife and I have Dell laptops and they typically draw from 20-25 watts.  But if I do something such as process a movie that works the laptop harder the wattage draw will jump to 30 or more.

We have 12 volt power jacks in our house that were installed when we started with a 12 volt off-grid power system.  We never used the AC "power brick" to run our computers.  We bought mobile adapters for our laptops that convert the 12 volt DC power to 19 volts to run the laptop.

When we changed our system to 24 volts and put in our pure sine wave Xantrex inverter we have since switched to using the "power brick" to run the laptops.  I checked the power draw and there's no difference between using the mobile adapters we used previously, vs the AC "power brick".

One thing I did find out though - the battery in my laptop is no good and needs to be replaced.  It crashes or goes dead if I unplug the "power brick".  If I put it to "sleep" and then the loads in the house drop below the inverter's search mode watts, the draw from the power brick is not enough to keep the inverter out of search mode.  When it drops into search and starts pulsing it crashes my laptop.  If I use the "hibernate" feature of the laptop, then it's fine.
--
Chris

[MagicValleyHPV]

To save power on a laptop, you would disable the keyboard backlight, dim the display as much as you can stand, mute the audio, use only one ram chip if you can get by without adding one, swap out the hd for a SSD and not use any usb devices or external mouse or keyboard.

Agreed, but those steps mentioned (except for the SSD), usually result in a displeasing experience - especially when the user spends upwards of 2-4 hours as I do on CAD.  Under those conditions, a newer and more efficient multi-core platform (especially with LED backlighting) is prudent.

My old laptop was a Thinkpad T43.  With a 14" screen and a single core, it would use only 8-12 watts under conservative operation.  You could get it down to 6 watts if you were crafty.

How, exactly, did you measure your wattage? Is this machine you speak of a Pentium "M" w/CF backlighting? If so, here's IBM's predictions: http://www-307.ibm.com/pc/support/site.wss/MIGR-58317.html#pow

"Li-Ion battery pack:
six cell, 10.8V, 4.4Ah
nine cell, 10.8V, 6.6Ah

Battery operation times(*2):
Six cell Up to 3.8 hours
Nine cell Up to 5.7 hours
Nine cell plus bay battery Up to 7.4 hours"[/i]

Something else to consider. My Apple MacBook Pro has a battery charger that floats the battery. It charges and discharges in cycles.

As I am currently doing, I run WITHOUT the laptop battery - most of the time, I'm either plugged in to AC (if available, when temporarily docked), or via my 24v bank (primarily). As per recommendations, I charge my laptop's battery to 50-60% then store it in a cool environment. As is well established, two conditions shorten the lithium batteries life;

1. heat
2. always fully charged

And as I suspect you already know, they are expensive to replace.

The only time I suck from the on-board 'puter battery, is when I wish to go outside, under the stars and play on the web, or chat with my kids, or dink with a CAD project. All other times the unit's battery is pulled.  

[richhagen]

In a computer lab I assisted with putting in on a remote Island in Fiji, BTHumble, the fellow I went there to assist, got the laptops we had available down to about 12Watts on average, replacing the HD's with CF cards for them, resetting the Bios settings and basically the other steps that Dnix71 outlined previously.  I was impressed that the siix laptops could run off of 6 amps of current from a 12V bank for teaching typing and other basic computer skills. Rich

[MagicValleyHPV]

Rich, Thanks again - I assume that was you who produced the lengthy write-up w/many interesting photos... yes? Loved the ingenuity.