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At Oxford, a Battery That's Lasted 175 Years -- So Far
sarahnaomi writes There sits, in the Clarendon Laboratory at Oxford University, a bell that has been ringing, nonstop, for at least 175 years. It's powered by a single battery that was installed in 1840. Researchers would love to know what the battery is made of, but they are afraid that opening the bell would ruin an experiment to see how long it will last. The bell's clapper oscillates back and forth constantly and quickly, meaning the Oxford Electric Bell, as it's called, has rung roughly 10 billion times, according to the university. It's made of what's called a "dry pile," which is one of the first electric batteries. Dry piles were invented by a guy named Giuseppe Zamboni (no relation to the ice resurfacing company) in the early 1800s. They use alternating discs of silver, zinc, sulfur, and other materials to generate low currents of electricity.
From The Fucking Article
"You'd think it'd be annoying as hell for a bell to be going off, constantly, for 175 years—but the voltage left in the battery is so low that the human ear can't actually hear the ringing. Instead, the clapper oscillates back and forth between the bell constantly, which you can see happening in this video. At this point, the experiment is more of a curiosity than anything—Croft says that the battery pulls 1 nanoAmp each time it oscillates between the bell’s sides, which is an exceedingly low amount of energy."
Actually the janitor changes it once a week when he cleans the room.
At the current estimated power draw, thats only (1 nanoampere) * 175 years = 0.00153401723 ampere hours. It's a long time: impressive durability, but not really amazing capacity. Laptop batteries are often ~1000 times that. I don't know the voltage here, so I can't do energy comparisons, just total amp hours.
http://en.wikipedia.org/wiki/N...
The Karpen Pile, currently on display at the Dimitrie Leonida National Technical Museum in Bucharest, Romania, still gives out 1V after 60 years.
This one has a glass enclosure so it can be studied.
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I assume the bell used to actually ring, and therefore pulled more than 2 nanoampere for a good while.
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I'm sure Chuck Berry would agree that is an awfully long time to be playing with your ding-a-ling!
Actually I have to correct myself. I assumed it was low voltage, like a single cell battery, and thus around 1-2 volts. That's not the case - the voltage is around 2,000 volts:
http://www.sharingtechnology.n...
That means my calculations were off by a factor of 1333. So if you divide the times I stated for AA and D batteries by 1,333 and you'll get a more accurate figure. So even a deep cell 12 V battery, which is around 120 watt-hours, could only run the bell for 9.5 years. Guess that makes it more impressive than I thought.
Or my calculations are still way off.
Better known as 318230.
Deep space tends to be very cold
This is misleading at best.
Space in itself is a near vacuum, which (a) has no temperature of its own, and (b) is a wonderful insulator. Which is why a thermos uses vacuum for insulation.
Objects in space can become very cold over long time spans, as heat slowly radiates away without being replenished at the same rate. But space itself doesn't cool them down.
Voyager 1, which is the operative craft that's been in service the longest and receives the least amount of heat from the sun is, after most of the heaters have been turned off to conserve energy, running at around -80C temperatures. That's a veritable furnace compared to other older objects in space that have radiated away more heat over much longer time.
Also, you say "chemical batteries". Well, yes, it is, but this is a dry battery. The composition doesn't change with colder temperatures, unlike wet batteries where liquids freeze. Dry batteries don't have that problem, which is why it is interesting.
This is why a desert can go from 100F to near freezing in a matter of hours when the Earth rotates and the desert is radiating heat out into space.
Deserts are not vacuums. Deserts cool down at night mainly through air convection. High altitude air on the planet's night side is less buoyant, and is replaced by warmer air from lower altitudes, and this process repeats all the way down to the surface. Katabatic winds are often a result, which the California "sundowner" winds is a good example of.
Needless to say, that isn't much of a concern for the microclimates of spacecraft.
FTA, it takes around 1 nanoampere to ring the bell once. It rings around around 2 Hz. Thus it takes 2 nanoampere a second, which works out to 7200 nanoampere-hours.
Ouch! Your bad maths is making my head hurt. Amp is a measure of current, not energy or charge.
A nA is one nano-couloumb per second. WTF does "nanoampere a second" even mean? Current acceleration?
One nano-Amp for an hour is precisely one nano-Amp hour, duh!
Better known as 3.6 microcoulombs. At 2kV, it is 7.2 milli-joules of energy.
For that idiocy you get a +5? Mods need to stay in school.
The better AAs produce 3 amp-hour of power. That is 3000000000 nanoamperes.
FFS! First you equate amp-hours with power, and then you equate it with amps. Where did the time unit go? :-) /.?
Your 3AHr battery at one nano-Amp will last 3 x 10 to the 9 hours, or 342,000 years. (neglecting internal leakage
Of course you will need a few of them in series to equal the 2kV of the Oxford Bell.
What has happened to
(disclaimer: After that rant, I'm almost certain to have made an error myself.)
I don't think that's true. On a cloudy but windy night in the desert it doesn't get nearly as cold as on a clear windless night all other things being equal. In fact when I searched for "Desert nighttime cooling" here is the first thing that came up. It basically says under clear low humidity conditions at night radiative cooling is by far the the largest reason for cooling.
Deserts cool down at night mainly through air convection
So where are those supplies of near-freezing air around desert areas ?
That is true as far as it goes, but in a sufficiently large, flat desert you don't have much winds, and dry air has much lower specific heat, so it can't conduct heat away from surfaces nearly as fast as moist air. Nevertheless desert nights are usually much colder than you would expect.
What's special about deserts in this regard is that same dry air also means the atmosphere is much more transparent to infrared than, so that far more of the thermal energy radiated towards the sky by the soil escapes from the Earth entirely, rather than being reflected back to the surface. It's basically the exact opposite of the "cloud blanket" effect where dense clouds that blow in near dusk can keep it from cooling off much overnight because the greatly elevated water levels in the clouds reflect much more of the radiated heat. (obviously the effect is much less pronounced in coastal deserts where the air is heavy with moisture even if it rarely rains.)
We actually had a post here several weeks back of a new surface designed to harness the effect for cooling anywhere at any time of day: it was highly reflective over the high-energy solar spectrum, and tuned to radiate thermal energy at a specific frequency at which the atmosphere was almost perfectly transparent. More primitive technology such as coolth cells work like an inverse solar heater - heat is radiated away from a thermal reservoir overnight, and the cold water used to chill the air during the day.
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