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2010-12-20
, 14:36
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Posts: 2,050 |
Thanked: 1,425 times |
Joined on Dec 2009
@ Bucharest
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#32
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Originally Posted by Joseph.skb
Wrong problem. Sun delivers about 900Wh per sq meter in a sunny day. That's 100x100 cm, or 10,000 sq cm. That gives about 90 mWh per sq cm. A phone that's 10 by 7 makes for 70 sq cm, or 6300 mWh, or 6 Wh.
With solar panels now finding a more common spot on residential roofs and other places never before, I'm sure the technology for simple mobilephone battery could be improved. If I'm not mistaken it was also mounted on the Mars rover.
N900 battery is 1300 mAh by 4V approx, so 5200 mWh, about 5 Wh roughly.
Math is nice but in real life you need: charge disspation that's around 20 percent, solar cell efficiency that's about 20 percent, 29 for the really cool stuff (remember, it works only with a limited spectrum).
So that's a 6-7 Wh battery from a panel that gives 6 W by 30%, or about 2Wh.
Ignoring the fact that no battery can sustain full charing current all the time (over 80 percent it's trickle), that still gives you 3 hour charge, on a sunny desert day, from 0 to about 80something percent.
Unless you are in the desert, tough.
It's not a matter of perfecting it. Solar cells have a theoretical eficiency of 29 percent. Sun delivers 1366 Wh per sq meter, but likely not on your latitude. So, basically, you need bigger sails.
And I haven't even tackled clouds, pollution, angle, heat disspation of electronics, variations of light flux, all of which kill figures and destroy batteries.
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N900 dead and Nokia no longer replaces them. Thanks for all the fish.
Keep the forums clean: use "Thanks" button instead of the thank you post.
N900 dead and Nokia no longer replaces them. Thanks for all the fish.
Keep the forums clean: use "Thanks" button instead of the thank you post.
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2010-12-20
, 18:34
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Posts: 1,341 |
Thanked: 708 times |
Joined on Feb 2010
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#33
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Originally Posted by ndi
The distance is the key. We would not need amplifiers and dB-boosting antennas, if we could get 2W EM-signal everywhere from APs, GSM-cell-towers, TV/Radio-stations.
All around you there's EM radiation in the order of watts. There is enough to power a radio from the antenna alone if it's big enough. No effects have been observed this far, aferage lifesoan continues to grow in spite of EM, chemical, biological, superbug and whatnot pollution.
While high EM has been noted as a possible cancer factor, we're talking people living under power lines, which took in equivalents of hundred of watts hour. The phone doesn't exceed 4 W under the worst conditions and not for 24 hours for decades.
Even so, the emissions of you phone is a drop in the bucket, considering that in that area you have several APs, GSM, (several networks), a few tens of radio stations, a few TV stations, walkie-talkies from taxis, satellite coverage, power line hum, EM from electronics and PCs, lighting, space humming, and all kinds of other stuff all over the spectrum.
Not to mention hight energy stuff from the sun and ionizing stuff from space.
Don't let EM spoil your N900.
But cellular phone radiating EM @ 2W one inch from your testicles or ovaries (or brains) several hours a day may cause damage.
Made by evolution, we are capable to some extend to tolerate sun light and other "normal" natural EM radiation, but now a new era has started when we have max ~2W EM radiator in 50 - 3000 Mhz just right behind our skins.
As batteries come bigger, we tend to use more data on our phones for all kind of facebook-, wheater-, RSS- widgets.
We know, cancers take years to develop, so the final truth about the dangers with cellular phone EM-radiation is not yet known.
Originally Posted by ossipena
You are short sighted here. Machine learning is getting better and better and we will have butlers (AI) which will do the quality control for us and filter the data (video,voice) which we are interested.
it would require so much time to filter what is good to keep and what not that it will be completely useless....
Just look how fairly well spam-filtering works already nowadays.
Besides, one could delete everything always after some time, even one day, and then just if something interesting has happened, would save that data. But when something suddenly happens "out there", you usually are too slow to capture it manually.
Also torrent servent on phone wouldn't be a bad idea, if we have practically limitless battery life.
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2010-12-20
, 20:24
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Posts: 2,050 |
Thanked: 1,425 times |
Joined on Dec 2009
@ Bucharest
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#34
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Originally Posted by zimon
Good point. It MAY also cause one to win lottery. No reliable source >> FUD.
But cellular phone radiating EM @ 2W one inch from your testicles or ovaries (or brains) several hours a day may cause damage.
Originally Posted by zimon
You know, either you quote some facts, it's still FUD. The fact that we evolved melanin protection to ionizing radiation and no defense against visible spectrum suggest, if anything, that we don't care. The sun delivers 1360 W/ sq meter. We love the sunlight.
Made by evolution, we are capable to some extend to tolerate sun light and other "normal" natural EM radiation
Cancer isn't an enigma. Just because we don't know how to stop some forms of cancer (yet) doesn't mean it's misunderstood or untreatable.
"Common environmental factors leading to cancer death include: tobacco (25-30%), diet and obesity (30-35%), infections (15-20%), radiation, stress, lack of physical activity, and environmental pollutants"
Any by "radiation" they don't mean EM comm range, they mean ionizing radiation, mostly by contamination of water and food with unstable elements from accidents, nuclear tests and shifting deposits. Also, from the fact that average Joe keeps drinking bottled water in spite of the fact that no bottling water plant has the rigors a mass water distribution system has. Not the tests, nor the legislation and inspections.
So you see, we KNOW what causes 95+% of cancers. There isn't enough room to fit a craze in there.
Life's too short to worry about EM.
__________________
N900 dead and Nokia no longer replaces them. Thanks for all the fish.
Keep the forums clean: use "Thanks" button instead of the thank you post.
N900 dead and Nokia no longer replaces them. Thanks for all the fish.
Keep the forums clean: use "Thanks" button instead of the thank you post.
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2010-12-20
, 23:19
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Posts: 752 |
Thanked: 284 times |
Joined on Sep 2010
@ Malaysia
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#35
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Originally Posted by ndi
That's considering charging up a totally empty phone battery. Also in handheld calculators, it's an ongoing process and you could use artificial light, instead of the sun only, right?
Wrong problem. Sun delivers about 900Wh per sq meter in a sunny day. That's 100x100 cm, or 10,000 sq cm. That gives about 90 mWh per sq cm. A phone that's 10 by 7 makes for 70 sq cm, or 6300 mWh, or 6 Wh.
N900 battery is 1300 mAh by 4V approx, so 5200 mWh, about 5 Wh roughly.
Math is nice but in real life you need: charge disspation that's around 20 percent, solar cell efficiency that's about 20 percent, 29 for the really cool stuff (remember, it works only with a limited spectrum).
So that's a 6-7 Wh battery from a panel that gives 6 W by 30%, or about 2Wh.
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2010-12-20
, 23:32
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Posts: 992 |
Thanked: 738 times |
Joined on Jun 2010
@ Low Earth Orbit
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#36
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Originally Posted by Joseph.skb
The power consumption of a phone is orders of magnitude greater than that of a calculator. I'm looking at a real old calculator (30 years old!) and it uses 0.7mW - I suspect newer calculators uses even less power.
That's considering charging up a totally empty phone battery. Also in handheld calculators, it's an ongoing process and you could use artificial light, instead of the sun only, right?
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2010-12-21
, 01:10
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Posts: 134 |
Thanked: 91 times |
Joined on Nov 2009
@ Imperial College London
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#37
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Originally Posted by ndi
The theoretical efficiency limit for a single junction cell is 31%. The really cool stuff at the moment can do over 40%, and the theoretical limiting efficiency for any solar cell is over 80%. Search for "3rd generation PV" for more details.
It's not a matter of perfecting it. Solar cells have a theoretical eficiency of 29 percent. Sun delivers 1366 Wh per sq meter, but likely not on your latitude. So, basically, you need bigger sails.
And I haven't even tackled clouds, pollution, angle, heat disspation of electronics, variations of light flux, all of which kill figures and destroy batteries.
Obviously these efficiencies won't be practically achievable for a long time, but sooner or later...
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2010-12-21
, 12:55
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Posts: 2,050 |
Thanked: 1,425 times |
Joined on Dec 2009
@ Bucharest
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#38
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Originally Posted by Joseph.skb
N900 draws like nuts. Under heavy use, it drains faster than USB can charge it. And USB drives 2.5 W (5v 500mA).
That's considering charging up a totally empty phone battery. Also in handheld calculators, it's an ongoing process and you could use artificial light, instead of the sun only, right?
Under less than desert conditions it might be that even low usage drains. N900 has 5 hour talk time under 3G. Add speakers or BT and solar can't even maintain a call.
Plus, if you talk you probably have poor incidence and a hand over it.
No way around it for now. You need big panel and not glued to phone.which makes it less portable than a second battery and an emergency pack.
__________________
N900 dead and Nokia no longer replaces them. Thanks for all the fish.
Keep the forums clean: use "Thanks" button instead of the thank you post.
N900 dead and Nokia no longer replaces them. Thanks for all the fish.
Keep the forums clean: use "Thanks" button instead of the thank you post.
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2010-12-21
, 13:44
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Posts: 1,503 |
Thanked: 2,688 times |
Joined on Oct 2010
@ Denmark
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#39
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The Solar option could just keep it alive when it is used very lightly and that would still be a good thing to have in those emergency situations....
Or if you shut off the N900 and keep it in the sun to charge....
and it might use up to 2.5W under heavy usage but i still think that's awesome compared to a laptop that uses over 10W.
And very funny when comparing my N900 to my OLD PII266 labtop that i use for DOS and DOS games, it uses more than 10W and is not even near as powerful as the N900.
It's so funny to look at the efficiency of electronics now a days compared to 10years ago or more
Or if you shut off the N900 and keep it in the sun to charge....
and it might use up to 2.5W under heavy usage but i still think that's awesome compared to a laptop that uses over 10W.
And very funny when comparing my N900 to my OLD PII266 labtop that i use for DOS and DOS games, it uses more than 10W and is not even near as powerful as the N900.
It's so funny to look at the efficiency of electronics now a days compared to 10years ago or more
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N900 @ 850MHz (LV) & 3044mAh Battery
Battery Tests and Battery Mod / Homemade 3000mAh XL Battery - (DONATE)
Custom Brightness & No Light Sensor
N900 DIY Micro Amplifier, turn your N900 into a home stereo
Fix you USB before and after it breaks
Feel free to contact me through PM, Skype or G.Talk
N900 @ 850MHz (LV) & 3044mAh Battery
Battery Tests and Battery Mod / Homemade 3000mAh XL Battery - (DONATE)
Custom Brightness & No Light Sensor
N900 DIY Micro Amplifier, turn your N900 into a home stereo
Fix you USB before and after it breaks
Feel free to contact me through PM, Skype or G.Talk
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2010-12-21
, 13:50
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Posts: 259 |
Thanked: 55 times |
Joined on Apr 2010
@ Vilnius, Lithuania
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#40
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One can dream...
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Mobile History: Nokia N900, 6300, Siemens CX75, SX1, CX65, Nokia 3100, 8210.
Mobile History: Nokia N900, 6300, Siemens CX75, SX1, CX65, Nokia 3100, 8210.
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| Tags |
| battery life, carbon nanotube, research |
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Will ad this little charger on my phone mod thread soon.
The little circuit puts out 900mA because it's of the 500mAh circuit's joined together + a 100ohm resistor on the data pins on the USB, the resistor limits the output to 900mA.
N900 @ 850MHz (LV) & 3044mAh Battery
Battery Tests and Battery Mod / Homemade 3000mAh XL Battery - (DONATE)
Custom Brightness & No Light Sensor
N900 DIY Micro Amplifier, turn your N900 into a home stereo
Fix you USB before and after it breaks
Feel free to contact me through PM, Skype or G.Talk