Does switching off and on consume more power than standby?
 

This has been mentioned as a side-topic in other threads, but can anyone give me a straight answer:

1. If I switch off my tablet and then switch it on a few hours later, does that consume more power than if I just leave the tablet on standby for the same amount of time?

2. If that's the case, at what point does it become worth switching it off to save power? A day? Two days? A week? Or is it never worth switching it off because the battery runs down anyway?

Re: Does switching off and on consume more power than standby?
 

As is apparently from the wildly differing battery life claims, there are probably too many variables here to really say for certain. So, more specifically, what's the consumption of a shutdown and a startup versus 1 hour of idling (say, with 2 SD cars in offline mode).

The convenience factor should also be taken into account here. The device is really designed to be left on 24/7 (the ARM and wifi powersaving are particularly impressive).

Sorry I don't have any hard data.

Re: Does switching off and on consume more power than standby?
 

not sure about exact numer when it pays off but it is measured in days. I think some nokia engineers in maemo-developers list mentioned few times that one reboot is worh of several days of standby.

Re: Does switching off and on consume more power than standby?
 

I've not checked the dev list but I've seen it in a bug report, https://bugs.maemo.org/show_bug.cgi?id=2673#c25

Re: Does switching off and on consume more power than standby?
 

I've wondered about this too. I will say this though, about two weeks ago I had turned off my tablet the night before a class and it had "2 hours in-use time", that particular class was 2 hours long so I figured it would be save just to turn it off right? Well the next day when I got to class I turned it on (after having been left off all night) you would think I would probably have about 2 hours of in-use time left right? Nope! It said "less than 1 day idle, less than 1 hour in use" that means not much left, and it actually ended up being about 5 MINUTES of usage time (on lowest brightness, blah blah), (that was pretty unfortunate too since I keep all my notes on my tablet :() anyway I will say that these days I just leave my tablet on all the time, even if I don't plan on using it for days.

Hope this helps.

Re: Does switching off and on consume more power than standby?
 

I have found that the command line app "battery-status" is far more accurate... it gives you the remaining battery capacity in percentages, instead of trying to "guess" how many hours of use time you have left. You should find the deb for it by searching this forum.

Re: Does switching off and on consume more power than standby?
 

Thank you SO MUCH for all the replies!

I'm doing a tutorial on power saving so I wanted to check with people on here before deciding what to say about switching off or standby.

I think on balance I'm going to tell people to leave their tablet switched on, especially as people involved in tablet development seem to be giving out this advice.

I've certainly heard experts say this about smartphones, that they load and run so much setup stuff when they switch on that it's better to leave them on standby, so this may well be true about the tablets as well.

Re: Does switching off and on consume more power than standby?
 

I don't have hard numbers either, but I've also noticed that booting up takes some juice. I would only switch off my N800 if I had to leave it behind for more than a week. If fully charged I would even stretch that a bit.

Re: Does switching off and on consume more power than standby?
 

It's definitely taking up a lot of juice when powering on.
The power management has not kicked in yet, the screen brightness is at its maximum the CPU probably is running at its maximum speed due to a lot of data being processed and daemons being run, it has to check all the peripherals before putting them into sleep mode or deactivating them, so ALL of them are for sure active and draining power from the battery.
The GPS chip is on initializing itself, the Bluetooth and WiFi chip too and, later, probably they are going go to look for available connections.
The flash memory is being read as the system and daemons and so on (applets, interface, libraries, you name it) load into RAM.
The card needs to be checked and the crawler needs to go look if there are new media files on it...

This alone it's a lot of stuff and almost everything is done at more or less the same time (those seconds it takes to load).

I usually bring it with me in the lab and leave it idle most of the time connected to the WiFi (I could say 95% of the time it's there sleeping and warning me of new IMs or mails, that's it) and at the end of the day the battery indicator is still full.
I use it the evening pretty much to browse the web and chat and reply to some mails every now and then while watching TV or spending some time with my girlfriend.
It usually goes to sleep with me with the battery indicator still full (but I know it's kind of lying to me).
If i let it run (may be I put it in offline mode), the next morning is still full or one bar (only one bar) has gone.
Today is such a day, it's 12pm (time for lunch!) and the battery indicator is half way telling me I have 1 hour of usage and 3 days of idle!
But, sometimes (very rarely and mainly because of modest being stuck trying to download mails) I turn it off the evening and on the morning.. those days it ALWAYS tells me I need to charge the battery.
Always.

And, to be complete, this are my settings: default ones. Brightness settings have never been touched, I've activated the blue led to tell me if it's on or not (that adds to battery drain), Bluetooth is alway on, but not visible (no icon for me) and WiFi is always connected (either in the lab or at home) and during lunch I move to another lab where it automatically switches to that WiFi AP while during the day I go to get some coffee two or three times and there's no WiFi down there (that all adds up to battery drain).

Overall I am VERY impressed on how it behaves when it comes to power management. Very. It's awesome.

Re: Does switching off and on consume more power than standby?
 

You might want to take into account that the locking keys and screen doesn't help. The moment the pop-out camera is pressed, the keypad and screen becomes active. This alone is the reason why I have to keep my NIT switched off most of the time. I'm storing it in my coat pocket and most of the time, I found it switched on without my knowledge. I requested some solution to this problem but didn't get any sensible resolution to the problem. I have a soft pouch (similar to the "sock" delivered with the NIT) but the net effect of that is 10% (I mean, 90% of the time it still unlocks the keys on it's own). I'm waiting for something called "Soft Poweroff" that people have been talking about on the forums. It seems to be broken since the arrival of OS2008 for the N800. I've no idea what it is but hopefully, it's something that requires a little more than plain press on the camera to deactivate the keylock!

Re: Does switching off and on consume more power than standby?
 

If you edit mce.ini (/etc/mce); you can disable the camera unlock.

Re: Does switching off and on consume more power than standby?
 

I was kinda wondering about this very issue. I tend to toss the PlayThing into my bag, turned off, for the day (where it invariably slips out of the soft-felt pouch. I can't *wait* for my Proporta case to get here).

Then I end up turning it on as needed. This means lunch time at the local free wi-fi coffeeshop downstairs so I can check my emails and listen to the radio.

Then off it goes again until I get home. Later in the evening, I'll fire PlayThing up and listen to some more radio (or futz with the background image and themes). Then turn it off again for the night.

The battery indicator hardly ever says 'battery full', though. And that's kinda worrying me since PlayThing's definitely off for a good 8 hours at night and has been plugged into the charger once I get home and start listening to the radio until the next morning.

I take it that charging the battery can't be done while it's in use?

And even if it doesn't charge while in use, is 8 hours the norm for charging the battery?

Now, I'm all for just leaving it in stand-by... but that charge time seems excessive (not that it's even hit 'battery full' and I know today the thing's been charging for the last 11 hours).

Re: Does switching off and on consume more power than standby?
 

That depends upon a few factors, such as what you mean by "in use" and the charging source.

For instance, my N800 drinks its fill of delicious electricity in well under eight hours each night while on, but idle, and charging via the AC adapter with which it came. If I leave the display set to stay on while charging, it does take longer to reach a full charge, but still well under eight hours. I'll venture a guess that it's closer to half that time.

On the other hand, I have also depleted my N800's battery while it was charging. I had the display on full brightness, I was streaming audio from an Internet radio station, and I had the speaker volume turned up to maximum. Additionally, I had some other applications open doing various things in the background, and I was only charging via a USB adapter and an AC-to-USB wall wart.

Re: Does switching off and on consume more power than standby?
 

Wow. I'm completely amazed by this.

I seriously turn off my Nokia every time, even when I go have a quick smoke outside at home then come back in to turn it on again.

It's probably going to take awhile for me to change my thinking on this.

Not turning the system off doesn't seem to make any sense to me.

Oh well. Maybe I'm just dumb. :confused:

Re: Does switching off and on consume more power than standby?
 

The bundled wallwart outputs significantly more power than the USB spec (500mA versus 890mA), so that would explain your trouble.

Charge time is about 30-45 minutes to 80% and 2-3 hours to 100%. It's more or less full if in-use time says 7 hours when CPU is at lowest level.

That works fine.

You're wasting a lot more power by turning it off and on all the time than you're likely to use letting it idle when not in use.

Do you turn off your cellphone whenever you're not using it? Or your computer?

The tablets are designed to be left on 24/7.

Re: Does switching off and on consume more power than standby?
 

Whoah.

Just like 'fit to view' that screws up and slows down my New York Times web page, leaving the unit on all the time until it *really* needs a charge seems kinda counter-intuitive.

I obviously am still on the slippery learning curve here :)

Re: Does switching off and on consume more power than standby?
 

If you tell the browser to break websites, it's gonna break websites. :)

Then just plug it in when you're around a charger and not using it. You'll be using less power anyway, so you'll also be doing less charging.

Re: Does switching off and on consume more power than standby?
 

For those of you confused by this, compare switching on something simple like an electric fan to switching on a desktop computer: the fan starts working straight away (it might take a while to spin but it starts spinning immediately), whereas the computer takes a relatively long time to set itself up to begin work.

Some PCs can take several minutes before they've finished doing all their startup stuff, and the whole time they're accessing the hard disk, loading drivers, running various programs, really DOING stuff. Once it's done that the computer calms down, it hardly ever accesses the disk, hardly ever starts a new process.

A computer has to work a LOT harder to get into a state where it is useful, whereas simple electrical devices don't have to do any work. That's why computers might use a lot more power starting up than simple electrical devices.

Desktop computers don't run off batteries so we don't notice it, but they too probably consume more power starting up than being left on standby. Tablets do lots of startup stuff just like a desktop computer, they have to work hard too to get started.



Try NOT turning it off. Try leaving it on forever, charging it while it's switched on so you don't run out of battery life.


I have no idea why your tablet would take 11 hours to charge, unless you're running lots of battery-hungry applications while you have it in standby?

My tablets have never taken anything like that long to charge, even when I have Skype running in the background.



This isn't anything specific to the tablets, this is a general issue with complex computers that run off batteries. If they take more energy powering up than being on standby, then leaving them on standby may make the battery last longer than switching them off.


I have never, ever had the N800 camera come out by itself, so I think it's an exaggeration to say that locking the screen doesn't help. It might not help if the camera comes out, but that's fairly rare at least in my experience.

Plus N810 and 770 owners don't have a pop-out camera at all.

Re: Does switching off and on consume more power than standby?
 

Yep, and I understood that when I purchased and used the USB adapters. Even so, I'll admit to momentary shock when the low battery warning popped up while my N800 was charging.

Also, according to the fine folks at DealExtreme, the USB power adapter I purchased supplies 1000mA. I suspect that's not actually true, and let me tell you, it's disappointing that in this day and age we can't put our full trust in a web-based outfit that sells tech products of questionable origin at ridiculously low prices that include shipping all the way from Hong Kong.

Re: Does switching off and on consume more power than standby?
 

Yeah, in more than a year of using my device on a daily basis, I've never once had the camera come out accidently.

Doesn't really matter, though, as you can turn off this feature in /etc/mce/mce.ini.

Re: Does switching off and on consume more power than standby?
 

Yep. For instance, look at hard drive specifications. This Toshiba drive--just picked at random--consumes 4.7 watts at start up, but then drops to 0.85 watts when idle and 1.9 watts when reading or writing.

Re: Does switching off and on consume more power than standby?
 

Ah, yeah. I always turn off anything when not in use, even my cell phone, it's just habit for me. I don't want to suffer from some type of horrible, searing, electromagnetic flux disease because I keep all of my devices on while I'm at home.

Sorry, but I practice other forms of birth control. :)

Well anyway, I finally gave in to following your guys' advices today and I honestly have to say it was a good experience.

Mind you, I still shut it off three times today even after reading these posts, but finally, I resisted common sense and didn't do it.

I have no idea what happened, but my tablet has never worked better.

Before, I was getting like 5 frames per second scrolling through a web page. Completely chunky and hard to navigate (I thought this was normal). Now it's like 60 frames per second of pure silk to rifle through all of the four message boards that I frequent on the internet.

I'm sure it's just a pure coincidence, but I'm sold on this concept.

I will never turn it off again.

Thanks for whatever reasons, I think. :)

Re: Does switching off and on consume more power than standby?
 

I don't turn off the N800, unless I for some reason want to take the battery out. Doesn't happen often! I reboot occasionally, but only when I'm forced to - as in when there's an omweather (or other applet) upgrade, there doesn't seem to be a way of restarting home applets other than rebooting. Oh, and when flashing of course.

Which means that my 'uptime' (hit 'uptime' in xterm) sometimes gets quite high. As of today it's 35 days, which isn't by far the record.

As for charging:
- The unit can of course be charged while it's on.
- Don't be afraid of charging it whenever you get the chance (think like a soldier and sleep: Get it when you can, you never know when the next chance comes around).
- Don't worry about 'overcharging', this isn't NiCd batteries we're talking about.
- Try to avoid depleting the battery. Every time you do you reduce the lifetime as well as the capacity of your battery.
- Some applications take so much juice that when you keep it plugged in it never seems to reach 'full', even after several hours. Especially if you use a charger that provides less juice than the standard charger, but even with that one you may see this, e.g. if you run the internet radio while charging.
- Lastly, install a load-monitoring applet (e.g. load-applet-run or similar), then a glance at the status bar will tell you if there's some unexpected CPU usage before you e.g. go to bed - that'll avoid waking up to a low or empty battery because some application was running wild.

Re: Does switching off and on consume more power than standby?
 

One unexpected usage I discovered was the "autoscroll" feature of the RSS-Applet: it uses quite some CPU every few moments.
I've now disabled this option on my N810.

Re: Does switching off and on consume more power than standby?
 

Just to reassure you, a battery-powered device gives off very little in the way of EM, and what it does give out drops off so quickly that you'd have to have it permanently next to your skin in order to be affected by any possible ill effects (if they even exist). As EM waves radiate from their transmitter, they spread out so much that they carry very little intensity when you're even a short distance from their source.

People reading this might remember it from Physics lessons as the inverse square law:

http://www.pas.rochester.edu/~afrank...02_019_PCT.gif

The idea of the graph is to show how when you're just a short distance from a source of electromagnetism, it has lost almost all of its original intensity.

Also, the radio transmitters of phones etc aren't active when they're in standby. They might have very short bursts now and then to let the nearest tower/router know they're still there, but they don't really emit anything measurable unless you're actually using them.

You can test this yourself by leaving a phone next to a powered speaker to listen to its radio signals. You'll occasionally hear a sound while it checks in with the nearest mast, and you'll hear a lot of sound if you actually use the phone, but if it's just sitting there unused then the vast majority of the time there will be no sound at all.


I know it's hard to believe, indeed that's why I started this thread, but the more I think about it the more it makes sense.

I used to switch off the tablet, even though I kept my phone on, but now I'm never switching off portable computers ever again.

Re: Does switching off and on consume more power than standby?
 

MMy last reboot was in september of last year. This should also
give an indication of how many system 'upgrades' I've let pass...

Re: Does switching off and on consume more power than standby?
 

Looking at the posts here, there appears to be a concensus of leaving the N8x0 on and seldom rebooting--primarily for the purpose of extending useful battery life (as the boot process consumes significant power).

In a frequent install-new-app/try-new-app/uninstall-new app environment, rebooting can help make your OS run more effectively as those less-than-perfect applications often leave trash in your device, even after they have been supposedly uninstalled.

While looking at the processes running in my N800 (many of them "come and go" frequently...popping up in the list momentarily and then disappearing), it sure seems like there are more processes running under Linux than on my desktop PC.

I use Process Explorer on my desktop and laptop PCs to check processes when things aren't running up to my expectations. It's like looking under the hood of your car to see if something's come loose or needs adjusting.

Is there some sort of list of known processes that we should be aware of and ones that we should be suspicious of?

Re: Does switching off and on consume more power than standby?
 

No wonder you have such a terrible experience with the thing.

Re: Does switching off and on consume more power than standby?
 

Well, let's see:

- Number of SD cards munched by N800's firmware: 0
- Number of times softpoweroff stopped working: 0
- Number of times browser did something weird: 0
- Number of applications that won't work with new firmware: 0

As far as I can tell, I'm still ahead. I'm constantly thinking about "upgrading" to the last version of ITOS2007, but I always end up putting it off, because it's just too much trouble. If Nokia manages to produce a non-sucky version of ITOS2008 before the Pandora comes out, I might give it one last shot. Otherwise, I fear it'll be the mothballs for my Itablets...

My continuing gripes are with the general user interface of the thing, something which has only received token interest from Nokia.

Re: Does switching off and on consume more power than standby?
 

If I can chime in here, my old Zaurus is hardly ever powered off either. It does have a "suspend" button, however, which seems to be something the N8x0s lack, am I right? On suspend the screen goes black and the sound quits working and the wifi (if inserted) disconnects, but when I hit the resume switch again they all come back on as if they were never away. Rebooting the thing takes about 3-4 minutes of activity to bring up the CACkO O/S Qtopia desktop, and does eat a lot of power.

Re: Does switching off and on consume more power than standby?
 

Quote of the Day!!:p

Re: Does switching off and on consume more power than standby?
 

Anyway I think its good bootup sometimes, I am sure it works better if you turn it off/on sometimes :)

Re: Does switching off and on consume more power than standby?
 

Okay, it's been a couple of days now that I've followed the advice on this thread (i.e. not powering down my N800). Instead I set mode to Offline and then Lock screen & touchpad.

Before (with frequent power-down & reboots) I was charging the unit twice a day.

Now, leaving the N800 in a stand-by state, the battery is lasting for days!

In the HOW-TO guide, this power philosophy should be the very first item for new users.

Re: Does switching off and on consume more power than standby?
 

I think the problem here may be cultural. In Europe and Asia virtually everyone has a mobile phone (and I do mean everyone, even grandparents and children) so they're used to having a portable device that they never ever switch off.

Nokia is a European company so it possibly assumed that most people would know they shouldn't switch off the tablets.

Unfortunately the tablets seem to be most popular in North America, which doesn't have the same kind of "cellular culture". The mobile phone ownership percentage in the USA is very very low compared to other rich nations.

I'm constantly amazed by how many Americans say they don't own a mobile phone yet they own a $500 PDA, which to me (a European) is like saying you own a limousine but not a car. A mobile phone is the workhorse of Europeans and Asians, but many Americans still seem to regard it as a luxury.

Re: Does switching off and on consume more power than standby?
 

Well, no, the devices can be suspended in the typical deep-sleep mode of most computers, but hardware watchdog is gonna step in and reboot the thing for you because it thinks it's dead. :D

Really, though, ARM at idle isn't all that different from ARM suspended for the short-term.

Re: Does switching off and on consume more power than standby?
 

That's windowsism, that is. :rolleyes:

But, to be honest, ITOS appears to be rather frugal with runaway processes and for the regular user (that is: the user Nokia claims is its target audience) it's not that evident to kill them off.

So, congrats to Nokia for turning mobile Linux more into mobile Windows. What's next? A BSOD?

Re: Does switching off and on consume more power than standby?
 

Good thread. I was turning it off if it was going to be off for at least a few hours. I'm move out to more like I do my PC - I generally turn it off only at night.

And we're toying with getting rid of our cellphones. $67 /month that could go somewhere else. A gadget like a PDA is a one-time charge. Cellphone service costs you every month.

Re: Does switching off and on consume more power than standby?
 

Well, I think this is the reason why Europe and America differ so much, American mobile phone networks rip people off really really badly with their high prices, ridiculous restrictions and poor coverage.

America should have been leading the world with adoption of mobile phones as Motorola was a real pioneer in this field, but the US industry seems to have been held back by some greedy phone network operators who want to reduce competition as much as possible and lock customers into using their service.

The situation here in Europe is very different. My minimum monthly charge on my phone network here in Finland is about one US dollar, with unlimited outgoing calls anywhere nationally any time costing about 10 US cents a minute. I can use any device I like from any manufacturer, the network doesn't care where I put my SIM card or what I use it for. I'm not on any contract so I could cancel or switch to another network at any time without any penalty. If I pay 10 euros (about 12 dollars) a month I can get uncapped mobile data at 3G speeds. They also let people make free VOIP calls through their unlimited data service.

And Europeans have never ever had to pay to receive calls, it was utterly astonishing to hear that some Americans have had to put up with that kind of charge.

In fact at one point there was a network here in Finland which actually paid people to receive calls, because they shared a bit of the profit they made from the person ringing (the advertisements for this network featured people overjoyed at being coldcalled by various salesmen because it was putting money in their bank).

Re: Does switching off and on consume more power than standby?
 

and I bet Finland has actual heathcare that takes care of folks too?

http://www.laakariliitto.fi/e/healthcare/

yup...congrats to Finland for actually having a civilized country. Wish we did here.

Do you need a dependent? :p

Re: Does switching off and on consume more power than standby?
 

Was it really necessary to drag your political non-sense into this thread?