Temperature?
 

Using the internal-temp utility I checked the temperature. Imagine my surprise when it reported 52C (and about an hour later 45C). Is it even possible considering that translates to 100+ F. Which is when most CPUs tend to fry (not to mention the tablet is warm..but not hot or scalding hot for that matter).

Re: Temperature?
 

lol i thought you were gonna ask for a temperature reader USB add-on or osmething lol

yeah thats pretty hot - no fans tho, i wouldnt expect it to be freezing either

Re: Temperature?
 

Max temperature is gonna be closer to 70°C, maybe more.

Re: Temperature?
 

CPUs probably don't like being run over 100C, which is closer to 212F. Most desktop CPUS stay over 100F almost all of the time...

Re: Temperature?
 

Whats internal temp utility?

Re: Temperature?
 

100 F is about body temperature; if that killed chips, then there would be no chips left!

Re: Temperature?
 

Those temperatures are totally non-critical. Mobile Intel chips are routinely rated to work up to or beyond 100C (212F). You can literally boil water with them. I wouldn't worry about those temperatures.

Re: Temperature?
 

Re: Temperature?
 

Cool; they should be great for overclocking then. Most chips I was aware of couldn't take 100C at the die; if they can take more, then an atmospheric-pressure open-circuit phase-change cooling system (squirt water at it and vent steam) is plausible.

Re: Temperature?
 

Ah, ok. I was just worried since I remembered from my overclocking days on my desktop that temperatures that hot tended to fry chips (and motherboards with them). Thanks for the info.

And that would explain why my laptop's temperature too...

Re: Temperature?
 

talking about temperatures, would COLD affect any hardware (say -20C). any would include the n800 tablet and/or mmc cards.

I have the impression that its due to temperature that I keep loosing some data; is it possible.

Ilia

P.S. -20C ISNT A JOKE; Canada is really that cold :(

Re: Temperature?
 

Troubles can be had from cold; typically mechanical failures. Something contracts more than something else, and you no longer have electrical contact. Pluggable connections especially, but solder joints and the like can fail.

Re: Temperature?
 

Nokia says:

Re: Temperature?
 

Sure. If it's too cold the liquid crystals in the LCD screen will freeze. Afaik below -15-20 °C it starts getting critical for LCD.

Did happen once to the screen of my old Palm Vx. Luckily in this case everything did revert back to normal after thawing.

But as you wear such devices close to the body, usually the LCD screen shouldn't come even close to -20 °C even it's much colder outside.

Also batteries really don't like temperatures below zero.

Re: Temperature?
 

Also some oscillators used in clocking circuits will fail to start or *if* they do, may not clock consistently if they are too cold. So things may not turn on, or possibly lock up. I'm sure equally strange problems start to happen when it gets too hot.

Re: Temperature?
 

I've used mplayer on my N800 at ambient temperatures below -20C on *many* occasions, and below -30 more than a few, and the screen is fine. Mplayer performance is very poor, playback gets "impressionistic" I assume this is due to some CPU throttling to cope for the incredibly fast batter drain. A healthy and fully charged battery has no chance of getting through the Daily Show at -30, and playback quality sucks. Best to sitck the N800 in an inside pocket and play mp3s...

It's been my impression that draining a battery by use in cold weather takes more than one recharge to recover from, but recovery is very good eventually. My impression, I have not collected solid empirical data.

Re: Temperature?
 

When reading books in temperatures close to 30F my screen seemed to start to get dark and not respond as fast. I would then just stick it in my pocket for a while.

Re: Temperature?
 

Temperature does affect some certain passive components performance, such as electrolytic capacitors (not used in the tablet, AFAIK), and ceramic capacitors. Electrolytic capacitors ESR roughly doubles with every 30C temperature drop. Some certain "crappy" ceramic capacitors (such as Y5V, Z5U dielectric) are really "temperature dependent capacitances"... but are OK to use in commercial applicances that are always held at room temperature. (Your home computer, DVD player, TV etc.) I do not know what kind of parts have been used in tablets.

Also, copper conductivity is affected by temperature, and ferrite materials (used in transformers and inductors) performance change in different temperatures. Resistors do drift at temperatures... (But this is very minor compared to other components.

Another story is the semiconductors itself. Typically semiconductors are characterized to different temperature grades: commercial (0 - +70C), industrial (-40 - +85C), and military (-55 - +125C). Many cases the actual chip is exactly the same but the packaging material (military parts are normally ceramic chips, others are plastic) and testing is different. Typically manufacturers test commercial parts at room temperature only, while industrial parts are at least sample tested at full temperature range, and military parts are likely 100% tested at full temperature range. (This explains why the military parts are ridiculously expensive.) However, even if you exceed the 0- +70C range on commercial parts it doesn't mean that it will fail right away... it just means that the operation and performance is not tested or guaranteed outside that range.

So, the question that can low temperature cause data loss: Yes, I believe that it can. For example clock and data signals changes (timing, amplitudes, resonances at signal edges) at cold (and hot) and at some point the data is no longer interpreted correctly... and you have corrupted data. However, I do not know if temperature does affect flash memory if it is not being write/read at? (Do you experience data loss during operation, or after you have exposed the tablet in cold and brought it to room temperature, after which you noticed data loss?)

Re: Temperature?
 

I've never experienced data loss after cold weather use, nor crashing etc. Perhaps the impressionistic mplayer video output is due to some of the effects you mention (but audio remains unaffected). I don't know how much writing is going on during video playback...

If I'd known about the internal temp sensor I'd have recorded some numbers, but it seems we're done with the <-20 for the season.

Re: Temperature?
 

around -5 to -10C I've been trying to warm the battery by pressing my palm against the backing, my impression is that the screenflex discolours the image far more than at room temp. Reminds me of my old mountaineering headlamp with the battery that hung around the neck inside the insullated layers, I briefly thought about rigging an extension so the battery could go inside a mitten, maybe through the charger plug would be easy...

Sticking the unit into a pocket is fine, until it's too cold for futzing wtih mittens. At -35C ambient/-48C windchilll there's nothing going in & out of pockets...

Re: Temperature?
 

@mara:
when booting from mmc, after some time of operation, the system crashes (ex: hildon-desktop restarts; processes automatically die...). Sometimes, a reboot helps; but after about 1-2 weeks of SD card usage, it cannot boot from it anymore :(
My last card lost the ability to "read sector 0", and became garbage since I can't even format it anymore.

I'm trying to understand what caused this.

Ilia

Re: Temperature?
 

The most common trouble with cold is condensation: Bring a cold device indoors, and before you know it there will be water condensing on outside- as well as on inside surfaces and components. That may (nay, _will_) lead to electrical problems.

Re: Temperature?
 

It almost sound like SD card internal wear leveling is not working... are the memory cards you are using "known good brand"?

Re: Temperature?
 

52C isn't that bad under heavy load. My MacBook can hit 85C when I'm copying a DVD, running SETI@Home, etc.

Re: Temperature?
 

Just a warning about battery life at the extremes of temperature.

excellent resource here: http://en.wikipedia.org/wiki/Lithium...ure_and_charge

The salient point is that operating temperature has a huge effect on battery life.

Some general points on prolonging your Li-Ion battery (C&P'ed from that site)

Guidelines for prolonging Li-ion battery life

* Unlike Ni-Cd batteries, lithium-ion batteries should be charged early and often. However, if they are not used for a long time, they should be brought to a charge level of around 40% - 60%. Lithium-ion batteries should not be frequently fully discharged and recharged ("deep-cycled") like Ni-Cd batteries, but this is necessary after about every 30th recharge to recalibrate any external electronic "fuel gauge" (e.g. State Of Charge meter). This prevents the fuel gauge from showing an incorrect battery charge.[14]
* Lithium-ion batteries should never be depleted to below their minimum voltage, 2.4v to 3.0v per cell.
* Li-ion batteries should be kept cool. Ideally they are stored in a refrigerator. Aging will take its toll much faster at high temperatures. The high temperatures found in cars cause lithium-ion batteries to degrade rapidly.
* According to one book,[34] lithium-ion batteries should not be frozen (most lithium-ion battery electrolytes freeze at approximately −40 °C; however, this is much colder than the lowest temperature reached by household freezers).
* Li-ion batteries should be bought only when needed, because the aging process begins as soon as the battery is manufactured.[14]
* When using a notebook computer running from fixed line power over extended periods, the battery should be removed,[35] and stored in a cool place so that it is not affected by the heat produced by the computer.

Re: Temperature?
 

The list is good. Except for the point about recalibration by deep-cycling every 30th charge - I'm pretty certain this is only true for laptop batteries (with their stacked battery cells), NIT-type devices use, as far as I know, just a simple voltage meter to deduce the charge level. For the record, I've had my N800 for 13 months now and the battery meter behaves exactly as it used to 13 months ago (it's been fully discharged three or four times only by accident, and the last time was some 5 months ago).