Battery discharge rates for XPS 15 with Optimus (also XPS 14/17)

Hi. I recently purchased a notebook from another manufacturer with an i3 370m cpu and 425m gpu. I thought the notebook had optimus, but apparently it does not - it always uses the 425m, but it seems to underclock it at idle based on what GPU-z reports. I'm going back and forth on whether I'm going to keep it, or return it and purchase an XPS 15, as the pricing is pretty close.

At idle/light web browsing/using Media Player classic, I am getting a discharge rate of about 15000 mW with the 425m and i3 370m combo WITHOUT Optimus, which is working out to about 5.5 - 6 hours of battery life with the 9 cell that came with my computer.

I am wondering what I am missing by not having Optimus in regards to battery life? If anyone out there who owns the XPS 15 (or XPS 14 or 17) with an i3 or i5 cpu with Optimus could post their system's battery discharge rates (as reported by Battery Bar) at idle or with light web browsing, I would greatly appreciate it!

Thanks in advance.

 

Well, I don't have the spec you requested but I thought it might be interesting to compare a few different specs anyway.

XPS 15, i7 740QM 435M no Optimus, 4GB, 160GB X25-M G2 SSD, 1080p screen, 9 cell battery (8100mWh, 3.6% wear), wifi on and connected to an AP, idle:

screen at lowest brightness: 1930mW, eta 4:00h

screen at highest brightness: 2647mW, eta 3:30h

 

You should be able to manually force any program to use whatever gpu you want under Nvidia Control Panel > Manage 3D settings > Program Settings should it fail to automatically select the correct default.

 

This has nothing to do with my original post. I will remember this should I end up purchasing a notebook with Optimus.

 

How does it not have Optimus? I thought the Intel I3 and 425m both support Optimus since the Intel has HD Graphics? If not then I guess nevermind.

 

Not to get off topic, but as I stated in my OP, the notebook I purchased does NOT have Optimus, even though it does have an i3 cpu and a 425m GPU. I believe it is because my notebook has a 3D 120hz display, which I guess rules out Optimus.

I'm just trying to find out if the discharge rate at idle is significantly lower with the XPS Optimus systems than what I'm experiencing with my current notebook.

 

My specs are as follows:
XPS L501x
Intel I5 460m 2.53Ghz
Nvidia Geforce 420m w/ Optimus
4Gb Ram
500Gb 7200rpm HD

When I have about 7 tabs open in Google Chrome, listening to iTunes and just doing some casual browsing, it reports -1.8W discharge. While watching a standard resolution .avi file using Intel's HD Graphics it reports -2.1W. Watching a HD 720p .mkv video file on Intel's HD Graphics it reports -2.5W. While watching the same HD file using the Nvidia Geforce, it reports -2.9W. I used BatteryCare as my battery monitor program. Unfortunately it doesn't seem that I can configure the program to report in your units of milliwatts. Anyway, it does seem that Optimus clearly does manage battery usage more efficiently. Hope this helps.

 

Discharge rate of 1.8 watts sounds extremely low. Assuming a 6 cell battery with 50 Wh, wouldn't that give you about 27 hours of battery life?? Or is my math wrong?

 

Sorry forgot to mention I have a 6-cell battery. But I am just going by what BatteryCare reports. Perhaps their units are not calculated properly? However the ratios of the differences should still reflect the efficiency of Optimus.

 

Maybe my program reports in using a different time period? Perhaps yours is per second while mine is per minutes? Or is it the other way around. Anyways the ratios of the differences should matter most here imo. Anyway what is the notebook that you currently have?

 

Battery Bar reports discharge rate in mW per hour. Mine averages about 15000 mW per hour at idle, or 15 W per hour. This equates to about 5.5 - 6 hours of battery life with my 9 cell 96 Wh battery.

If your software is reporting 1.8 W per hour, that would equate to 27 hours of battery life (Assuming a 6 cell 50 Wh battery). If it's reporting 1.8 W per minute, that would kill your battery in about 30 minutes. If it's per second, well your battery wouldn't last 1 minute.

Sorry, just trying to understand your numbers. I appreciate you posting them.

EDIT: My current notebook is an Acer AS5745DG

 

Yeah I see what you mean. This is the first time I installed and used a battery monitoring program so I am not familiar with what to expect for related statistics. I am going try out Battery Bar and let you know.

 

Battery Wear: 3.7% of 5,200 mWh

On battery using Power Saving Mode.
Casual browsing with Google Chrome with 4 tabs and listening to iTunes: -1,803 mW
watching SD .avi file on Intel HDG: -2,019 mW
watching SD .avi file on Geforce: -2,245 mW
watching HD .mkv 720p file on Intel HDG: -2,187 mW
watching HD .mkv 720p file on Geforce: -2,533 mW

All the videos were watched with Google Chrome and itunes still running to ensure all else was equal. I would also imagine that running a game would command a larger difference between Intel's HDG and Geforce because games can demand much more from GPU's.

 

Thanks - greatly appreciated! My guess is your software misplaced the decimal and you're getting 18 W per hour with Chrome (7 tabs) and iTunes, which is pretty close to what I'm getting with the same applications running (albeit with a lot of tweaking to maximize battery).

I was hoping for better numbers from the Intel graphics - we'll see what Battery Bar tells you when you try it.

EDIT: Wow, those numbers are nuts! It really is reporting 1.8 W per hour. Hmmm.

 

I'm curious as to what numbers show up for you when you play a HD video?

 

What is Battery Bar reporting as your remaining battery life?

 

My statistics were reported when my battery life was at 93%.

 

Sorry, I meant how long will it last before depleted? If you click on the Battery Bar toolbar it will switch from percent remaining to estimated time remaining. You can also simply hover over the battery icon in the System Tray and it should give you the remaining time.

It seems that both you and the other poster with the i7 are getting completely different numbers from Battery Bar than I am. It's as though all my numbers are multiplied by 10.

 

I forgot to mention I have the HD 720p screen. Although I ordered an exchange for a new system with the FHD 1080p B+RGLED screen which should arrive tomorrow according to fedex.=P

 

Note that I have been charging my system since my last test for about 10 minutes, it reports 1:56 while casual browsing w/ Chrome and iTunes.

 

Okay, that is helpful. Your numbers are proportional to mine, considering you have the 6 cell battery and mine is 9 cell. My Battery Bar reports the following right now with Chrome running 7 tabs, and iTunes running:

Percent: 78.5%
Capacity: 75,769 mWh of 96,537 mWh
Discharge Rate -15,418 mW
Battery: 2:59 (Discharging)
Full Lifetime 4:06
A/C: Disconected
Battery Wear: 3.4% of 99,900 mWh

When I hover over the battery icon in the system tray, it reports 4hr 29min (77%) remaining. Not sure why there is a discrepancy between battery bar and the windows battery icon?

Thanks again for posting your numbers. I'll have to check my numbers while playing HD video, as that is probably where Optimus would be a huge advantage in battery life.

 

Anytime. However I am also curious while there is such a large discrepancy with your discharge rate units since mine is about -1.7 W while just browsing while yours is -15.4 W. Probably decimal misplacement.

 

Yeah, pretty sure that's all it is. My battery's capacity also appears to have been multiplied by 10 (or your's divided by 10), so it is proportional to the discharge rate.

 

Heya,

Playing a 720p mkv from the internal HD:

At minimum brightness, -2332mW, eta 2:02
At maximum brightness, -2983mW, eta 1:54

I haven't got a physical bluay disc to hand to try at the moment but can tomorrow if that would be more relevant?

 

I admit that this is not all that relevant, but the EE in me has to comment. Watts are a rate, i.e. Joules/second, of energy per time. That's why Wh (Watt-hours) is a unit of energy and why batteries are sometimes described in terms of Wh capacity, because it's their energy capacity.

I'm not familiar with Battery Bar, but if it's telling you something about W per hour or W per min, it's screwy. The only thing I can imagine is that it might say that you are using *on average* 15 W over the course of an hour, or that you used 15 Watt-hours.

Anyway, it seems like you all figured out the relevant issue already, but like I said, I felt compelled to throw that in... Carry on.

 

I'm pretty sure it is reporting the discharge rate based on the power consumption at that given moment. I don't think it is an average, as it changes too rapidly (one moment it may read 15000 mW discharge rate, the next moment while running a game it may be 40000 mW).

I don't know about the units, but it's obvious that it's reporting a unit of capacity being depleted per hour, based on the current rate of power consumption; so if it reports the discharge rate as 15000 mW, and the remaining capacity as 15000 mWh, the software will say there is approximately 1 hour of battery life remaining. Whether the units are used correctly, I don't know, but that is the math that the software is doing.

 

Just posting from memory, my battery is around 7500mWh capacity, and when I had no windows open, the battery was discharging at around 2500mWh. But geeze, it was all over when I opened Civ V. It was discharging around 7500mWh. It didn't even last an hour When I charged it, I think it charged around 4800mWh. I will look at it again tonight and post exact figures.

 

Thanks. Is your system one of the i3/i5 with Optimus, though?

 

No, but would be interesting to see a comparison to an i5 system. Although, I'm guessing just i5 vs i7 is already a large difference in battery drain even when the i5 is using the Nvidia video card. I know HWMonitor shows five thousand some mW just used by the processor when I am gaming.

 

Alienware M11X R3 here installed battery bar to test (nice program by the way)
This has optimus with integrated video, and switchhes to a Nivida 540M 2GB when needed.
Light browsing screen at 20% brightness, power saver power plan

Discharge Rate : -6,721 mW

While playing Skyrim (game) at full brightness ultra settings in max preformance power plan the discharge rate jumps to
-41,234 mW
wow what a difference

 

=)
First of all, Watts is measured not time dependent. When your device consumes 10Watts it does it every second and every minute and every hour. When your sum that all up, your get that "Volume" of kwh (kilowatt per hour).
Your Programm must be wrong! I think, and that seems reasonable for me, is that it shifts the comma one digit. -2.1 W is -21W (or W in mW is times 1000) so -21000mW. This should be ok, when you consider that the NV GPU is always on and that the "old" CPU is not as energy saving as the new Sandy Bridge CPUs. My XPS 15L502x uses 12~15W in idle. The NV GPU uses 3~5W in idle, so that should be the numbers your looking for.

YOu can download a programm called "BatteryBar" which i use. Its free and it does all the measurement fine and puts a nice little tolbar next to your tray(with current consumption or time estimated)

//EDIT The Snake: You might mention, that your cpu is low power cpu! My CPU has a TDP ow 45W, yours have 17W!

MFG Jubeltrubel