Battery Development Off The Beaten Path 308
Roland Piquepaille writes "Let's face it. Our computing devices are going faster year after year. But our laptop batteries don't show the same performance improvement. They still work only for a few hours, just a little bit more than ten years ago. Several companies want to change this, according to this UPI report, 'Nanotechnology improving energy options.' For example, mPhase Technologies plans to introduce smart batteries based on millions of silicon nanotube electrodes. These nanobatteries, to be introduced before the end of 2005, will last longer than traditional ones and will be respectful of our environment. Meanwhile, Konarka Technologies wants to reduce the weight of batteries with its flexible solar-fueled nanobatteries. You'll find more details and pictures in this overview."
XXX Small :) (Score:5, Funny)
Re:XXX Small :) (Score:3, Funny)
Lagging behind (Score:4, Insightful)
All the big talk is about fuel cells. Will these batteries really show much improvement or is it another marketing ploy
Re:Lagging behind (Score:5, Interesting)
Conventional (electro-chemical) battery technology is pretty much at a dead end. The energy density of a battery is not far off from that of dynamite, which means that there really isn't any further you can go while keeping the result stable. (A fuel cell is really a highly UNstable battery, but extra safeguards can make it usable technology)
Since many useful applications are now limited by battery life, this is an area where a technological breakthrough is highly overdue...
Re:Lagging behind (Score:5, Interesting)
Actually, the energy density of dynamite and other explosives isn't that much. Gasoline has more energy density. Forget about computers, if we could get a battery with the same energy density as gasoline, at a reasonable price, that would mean practical electric cars.
Re:Lagging behind (Score:5, Interesting)
Re:Lagging behind (Score:4, Interesting)
One - Practical implementations of Stirling Engines are rare. There are reasons for it that I am sure someone can explain. The elegant thermal cycle is well understood.
Two - Radioisotopes are rather difficult to turn off. If they disperse enough energy to make my laptop go for 9 hours of the work day, they are also generating energy/heat the other 15 hours. Stuff that laptop in a padded bag, put in trunk, wait a few hours and have a china syndrome car-b-que. It is a matter of energy conservation...it has to go somewhere!
You propose as an option a square piston in the engine...the trouble with this is sealing and wear at the corners. Also, precision boring and turning operations can holder better part to part tolerances.
Re:Lagging behind (Score:4, Interesting)
Fair enough. But they have been developed by NASA, and have been shown to be an effective way to produce quite a bit of power for not much radioisotope.
Radioisotopes are rather difficult to turn off.
This is the classic problem. You'd have to dissipate the excess energy in something like a heating coil or a mechanical fan. Dissipating about 30-40 watts shouldn't be too difficult, although it might get a smidge warm.
You propose as an option a square piston in the engine...the trouble with this is sealing and wear at the corners. Also, precision boring and turning operations can holder better part to part tolerances.
I've been curious as to whether this was a good design or not. Unfortunately, trying to get any *real* feedback has been worse than pulling teeth. Using a circular bore is certainly not out of the question. I only proposed a sqaure bore to reduce the footprint of the engine.
BTW, thanks for the feedback. I really do appreciate it.
Re:Lagging behind (Score:3, Insightful)
Re:Lagging behind (Score:3, Interesting)
Hmm... I thought that air-cooled Stirling engines worked because the heat would attempt to equalized the temperature inside the cylinder and outside in the open air. Perhaps I was incorrect. Many Stirling designs actually call for some sort of active cooling. NASA uses cycled helium for th
Re:Lagging behind (Score:3, Interesting)
I've long lost the link, but I had based it on a open air design I saw somewhere. The idea being that the piston would pass the exhaust port on the way up. When the exhaust port is reached, a heat and air exchange would occur. In the design I saw, gravity was supposed to bring the piston back down to compress the gas.
You do realize (Score:5, Insightful)
electric computers on the other hand are just over 50 years of serious development, advances should be more rapid in this field.
Re:Lagging behind (Score:5, Interesting)
"Man drops his cell phone and dies in explosion."
I took a class on ubiquitous comuting last year and what we studied about battery power suggested that the technology existed for more powerful batteries, but the current technology was entirely too dangerous to use with portable devices since they get beat up considerably. We don't have this danger level for the rest of the tech industry. If we did, I imagine that computers in general would be far less advanced.
Actually, they aren't. (Score:5, Informative)
The current battery technologies are:
Lead acid: 200 year old technology. Give this a performance index of 1. It's cheap and simple.
NiCd: Heavy metals but good high current. Performance of 2x the lead acid. Performance 2.
NiMH: Getting rid of the heavy metals. Lighter as well. Performance of around 3x that of a lead acid battery.
LiON: Light, performance 5 x that of a lead acid battery.
They obviously get more expensive the more advanced they are. You can expect to get around 70-80miles out of a lead acid battery. Multiply that by the performance factors for the newer technologies.
New technologies, still up and coming. Used in small scale applications, mobile phones, laptops.
Li-Poly. Lighter and can handle more cycles than LiON but not much more power.
Lithium Sulphur batteries (Li-S) promise to more than double the capacity of LiON batteries, 10X that of a lead acid battery. That's a 700-800 mile range on a single charge, not even Diesel vehicles get that. I think these will do the job of killing petrol vehicles. Superior performance, superior range.
Basically. You don't discard the batteries when they wear out. Trade them in at 100,000 miles and get a "new" or refurbished set.
This *is* all nifty technology but still expensive due to manufacturing capacity.
Re:Actually, they aren't. (Score:4, Interesting)
- Charge time
- Cold start (along with heating and defrosting) - battery powered are well and good for Florida, Texas, or California but may have issues north of the Mason-Dixon line.
Re:Actually, they aren't. (Score:5, Informative)
They'll work down to -40C. The charge time *will* still be an issue if you're doing seriously large milages over a short period, but they charge faster than existing batteries.
With a 700+ mile range, charging them overnight isn't going to be as big an issue. Certainly for commuting I'd only have to charge up every 2 weeks or so.
The guys pioneering them are here:
http://www.sionpower.com/
Re:Actually, they aren't. (Score:2)
I had a vehicle where the heater fan wouldn't work under 32F (I guess at that point, it's not much of a heater fan), and it was no fun driving 20-30 miles in that thing during the dead of winter.
Re:Actually, they aren't. (Score:3, Insightful)
In short, want better battery life? Get a shittier machine. Battery life on my wife's 2 year old iBook is better than that of my brand new Powerbook. Sma
Re:Actually, they aren't. (Score:3, Interesting)
But a diesel vehicle can have it's tank refilled in 10 minutes. It'll take several hours to recharge a bunch of Li-S cells. The solution would be to have fuel stations keep stacks of batteries fully charged - rather than going to the fuel station and recharging your own batteries, you could hand in your discharged batteries and pick up some freshly charged ones. The fuel station can then charge your discharged batteries
Re:Lagging behind (Score:2)
Maybe it has something to do with the fact that batteries have existed for over 200 years. Maybe we're nearing the brick wall of performance.
LK
Re:Lagging behind (Score:2)
Because they're obsolute. Get a USB keydrive, and you'll transfer 1.44 MB in a second (or faster.)
Re:Lagging behind (Score:2)
Floppy drives cost $20 anyways. And another $1 per 1.44 mb. AND they're volatile. Didn't they come out with super drives a while back, met with a quick and terrible demise because they were antiquated? Ditto zip drives and their ilk.
Floppy drives are just about only useful for making boot disks, or transferring files to computing relics. I'm sorry.
Why not nuclear batteries? (Score:5, Funny)
Re:Why not nuclear batteries? (Score:2)
Seriously though, whatever happened to fuel cells for laptops?
Re:Why not nuclear batteries? (Score:5, Informative)
Because consumers can't handle them. (Score:4, Insightful)
Really, you want to put plutonium, polonium, or other dirty bomb materials in the hands of the general public? The same public that currently tosses NiCd batteries into the trash when they're done with them? SRGs are a wonderful idea for military, for space, and for other heavily regulated and monitored uses (where RTGs are already used), but they're a horrible idea for the mass market.
Re:Because consumers can't handle them. (Score:3, Interesting)
The dangers of these radioisotopes have been highly overrated. You'd do just as much damage by dispersing a lot of the toxic chemicals that are in today's batteries.
SRGs are a wonderful idea for military, for space, and for other heavily regulated and monitored uses (where RTGs are already used), but they're a horrible idea for the mass market.
As I said in my previous post, I'd be ecstatic if
Re:Because consumers can't handle them. (Score:3, Informative)
http://www.spacedaily.com/news/nuclear-blackmarke t -02d.html [spacedaily.com]
http://www.llnl.gov/csts/publications/sutcliffe/ [llnl.gov]
The end result is very few (if any) people would die from the radiological effects. Of course, maybe the public would know better if Nader had done something useful and taken the nuclear challenge [wisc.edu].
Re:Because consumers can't handle them. (Score:3, Informative)
I might suggest bolstering what I say here with some research on the Internet, but the Health effects of radioisotopes break down by the type of radiation they release.
Alpha particles are basically free protons. They have very little penetration power and can be shielded against by a sheet of paper or your layer of dead skin cells. It's slow movem
Re:Because consumers can't handle them. (Score:5, Funny)
Re:Because consumers can't handle them. (Score:5, Informative)
Yes, the same public that tosses Americium-241 [uic.com.au] into the trash. Just because it's radioactive, doesn't mean it's a problem. Your backyard is radioactive. Your bar-b-que is probably more radioactive, as is the granite building you probably work in. The irrational fear of radiation has been holding back R&D for decades.
Even just using an alpha emitter like Americium, chemically bonded into a plastic and successively sandwiched between photo-electric cells to provide a "wireless" charger for existing battery technologies would be an immense (and safe) step forward. These technologies have been known and patented for a long time. Unfortunately, the monster movies of the 1950s have raised a generation that associates radiation with Godzilla, and prevents any rational use.
Re:Why not nuclear batteries? (Score:2)
Re:Why not nuclear batteries? (Score:2)
small problem (Score:5, Interesting)
Re:small problem (Score:3, Funny)
Nope, just go outside and wait until the lightning strucks it.
Re:small problem (Score:4, Funny)
Re:small problem (Score:3, Informative)
Come again? (Score:5, Funny)
What odd grammar. "Can you not see I am respectful of the environment?! Do not disrepect the spirits of your elders, buy Mr. Power Extra Subueteo Batteries now!"
Re:Come again? (Score:2)
I guess that begs asking, whose enviornment? Are they talking our as a company, our as in the part of the world they are made?
Re:Come again? (Score:2)
This reminds me of stuff I've seen on the Engrish.com [engrish.com] website. Full with very bizarre mangled English sayings. Fun for the whole family!
Ever notice.. (Score:4, Interesting)
Im serious.
Weve been using the same fuel for ages. That fuel explodes.
Perhaps Im jaded, but why, exactly, cant we economically synthesize fuel? (Perhaps that goes against the laws of thermodynamics?)
Meh.
Im bitter.
You're not jaded, you're simply ignorant (Score:4, Insightful)
The fuel that explodes, as you trollishly point out, has the nice property of having a remarkably high energy density, which means a little goes a long way. Again, those pesky laws of physics and chemistry rear their ugly heads.
I'm sorry that reality is not which you wish, but maybe the problem is not with reality, but rather the wishing?
Re:Ever notice.. (Score:5, Interesting)
We can. But there is one problem.
We can economically synthesize electricity. Electricity can be applied to water in order to separate the hydrogen and oxygen. The hydrogen and oxygen can later be rejoined (in a fuel cell) to produce electricity. This seems very simple but there are two big problems:
1) Today's fuel cells require large amounts of platinum. Although some companies sell fuel cells today, they are nothing more than a lab curiosity - you'll never see them powering more than a few prototype cars on the road because nobody will be able to afford them.
2) Hydrogen storage - hydrogen would be the perfect fuel if you could store lots of it with good gravimetric and volumetric densities. Right now, there is no method to stick a bunch (mass) of hydrogen into a small package. Even liquid hydrogen is lighter than air, not to mention that it would freeze the hell out of everything in the event of an accident. Right now, solid hydrogen [txohydrogen.com] is the most promising but still has a long way to go.
So yes - we can economically synthesize fuel. We just can't store it or make economical use of it. FWIW, today's nickel-metal hydride batteries are nothing more than closed-loop fuel cells. They contain water which is separated into hydrogen and oxygen when they are charged. The hydrogen and oxygen are recombined to produce electricity on-demand. The inventor [ovonic.com] of the NiMH battery is working on making this into an open-loop fuel cell [ovonic.com]. Since the battery version uses no precious metals, this is the most promising (IMHO) fuel cell for economical, volume fuel cell devices.
Think of it as a refillable battery instead of rechargeable.
Re:Ever notice.. (Score:2)
Fortunately, platinum is available in huge quantities in the asteroid belt. Unfortunately, it doesn't look like we'll have the technology to harvest it before I die.
Re:Ever notice.. (Score:2)
No it isn't. Air at STP weighs 0.0013 gm/cm^3. Liquid hydrogen weighs 0.07 gm/cm^3, about 50 times more.
Re:Ever notice.. (Score:2)
Second principle of the Thermodynamics
I only have a power cord... (Score:5, Funny)
Genetics is the key (Score:5, Funny)
Re:Genetics is the key (Score:3, Funny)
Not fun.
Respectful of our environment? (Score:4, Insightful)
Re:Respectful of our environment? (Score:2)
Lighter-weight hybrid automobiles? (Score:5, Interesting)
It could also mean substantially lighter battery pack units for hybrid drivetrains. A big issue with hybrid drivetrain cars is the fact the battery pack does take up quite a lot of space and also contributes to the deadweight of the car. By switching to these newer battery technologies they could reduce the size of the battery pack, which means more interior space and possibly even better fuel efficiency since when the gasoline engine is running you use less fuel because the car is now lighter.
Re:Lighter-weight hybrid automobiles? (Score:2, Insightful)
Exactly. If sufficiently efficient, it might also eliminate the need for a petrol engine entirely - after all, the only reason that hybrid cars (or diesel submarines...) exist is that the battery is a less efficient power source than burning fossil
Hybrids are a stop gap technology. (Score:2)
We don't need better batteries for cars, we just need to move off of the current combustion engine to a cleaner more available fuel.
Finally, there are gas and diesel powered cars that get better mileage than hybrids, and I am talking demonstratable mileage, not what you see on the EPA tag.
Re:Hybrids are a stop gap technology. (Score:3, Informative)
Yes, you see those in Europe, but those vehicles tend to be very lightweight to improve fuel efficiency even further. The Volkswagen Lupo diesel is a good example of this, but this version of the Lupo is so lightly built that I have serious worries about its highway safety.
Meanwhile, the current Toyota Prius get around 48 to 52 mpg in most people's
Re:Hybrids are a stop gap technology. (Score:3, Interesting)
I don't see how that follows. The batteries are mostly used for regenerative braking and for storing enough power for acceleration. The reason they are so large is that if you discharge them all the way it tends to damage the battery so they are only slightly discharged. THIS is the real problem with hybrids, if you had a battery technology that could h
Price? (Score:5, Interesting)
That said, CPUs and other components are designed these days to eat up less and less power, so perhaps there isn't even a need for more efficient energy storage?
Re:Price? (Score:5, Insightful)
So is just about everything till the patents expire and commodity-level competition kicks in.
Re:Price? (Score:4, Informative)
Power Consumption? (Score:5, Insightful)
Re:Power Consumption? (Score:2)
um, no (Score:2)
Years ago, they didn't figure for this. They had all the power they needed.
So, and I know this from my college studies in the area, batteries have not grown very much over the last decade. They are pretty much the same.
As somebody working in tech support... (Score:2, Insightful)
Mr. Sparkle? (Score:2, Funny)
Heh. I read this and immediately thought of the Simpsons episode with Mr. Sparkle. "Can you not see I am disrespectfull of dirt!"
About time... (Score:2, Insightful)
Of course in the not so distant future we will need to find new energy scources as our consumptions rise. Which of course would stem from manufacturers no longer trying to make energy efficient portable devices.
"Respectful of the environment?" (Score:2, Insightful)
Seriously, "respectful" is a very odd word to use there. If you're talking about "they are recyclable", or "they can be disposed of without leaching chemicals bad for [people, plants, animals] into the water table", then say so. Inanimate objects do not feel nor care about the welfare of life on earth.
--
Evan "The sign into Davis, CA proudly reads 'Nuclear Free'. What a negative town."
Hybrids? (Score:3, Interesting)
It's too bad nobody has found an effective way to "resuse" the heat generated by laptops to recharge the batteries.
Maybe we'll come full circle and have wind-up laptops; as your laptop starts slowing down, just wind it up.
Re:Hybrids? (Score:2, Funny)
Say hello to Mr. Entropy!
Aids soldiers as well... (Score:3, Insightful)
Perhaps this can be tied into yesterday's Slashdot story with athe Army? [slashdot.org]
Seems like batteries ARE getting better... (Score:5, Insightful)
Re:Seems like batteries ARE getting better... (Score:3, Interesting)
Lets see;
Lead Acid in the first laptops, then NiCD, then NiMH, now Li-ion. The cells have not only gotten lighter but can also store energy with higher density.
I'd love to see double the capacity in batteries but isn't this going the wrong way? If a device could be made to use
Re:Seems like batteries ARE getting better... (Score:2)
If you want to see an improvement, try an LED flashlight with new batteries. 4-6 hour battery life is a
Induction Charging (Score:5, Insightful)
What we really need is a standard induction charging scheme. [bbc.co.uk] Where I can carry my gadgets around, and not worry 'bout carrying one-wall-wart per device around all the time. If Im at *your* house, I put my device on your charger for a few minutes while we have a tea... if im at work, i set it on my desk (as i do now, sans the specific wall-wart ive left at home).
Putting the devices on an induction-charging station would make the duration of the charge moot... it would CERTAINLY be much longer than time spent between these pads....
Re:Induction Charging (Score:2)
I personally quite enjoy sitting out on the deck on top of my 3-flat and using my laptop. Or sitting at an outdoor cafe, and using my laptop. (And before you ask, I have unlimited GPRS, so I can and do actually work in these locations). Now, yes, I could run back in for an hour or two every 3 hours, but that's no good. I'd very much like better batteries.
Re:Induction Charging (Score:2, Interesting)
Re:Induction Charging (Score:3, Funny)
Cartman in charge of PR? (Score:2)
Nano-Wow! This is nano-cool! I can't nano believe the nano-things they can nano-do with these nano-days with chemistry and materials science. It's nanoriffic!
The VC's must be jumping all over this e-battery.co^H^H^H^H^H nano-battery.small stuff.
Not Free (Score:2, Funny)
Imagine "Battery sir... no charge"
Is there really little-to-no improvement? (Score:2, Interesting)
It seems to me that the manufacturers of products that use these batteries know what an acceptable length of time between charges is for their product and may not see the need to improve much upon that. What they do is convert the improved length-of-life to smaller electronics. They reduce the size of their product (smaller battery) while maintaining how long it
'Nanotechnology improving energy options.' (Score:5, Funny)
Oh wait, that's a perpetual motion machine...
What about Iron III (Score:5, Interesting)
An article in C&ENews (16/8/99) describes a new high-energy battery developed in Israel using iron as the cathode material. The new batteries store 50% more energy than the alkaline battery which uses a zinc anode, manganese dioxide cathode and potassium hydroxide electrolyte. The new cathode material which replaces the MnO2 has been termed 'super-iron' by Stuart Licht, Baohui Wang and Susanta Ghosh its inventors, however, it is not iron metal but an iron(VI) compound. iron(VI) is an unusual high oxidation state of iron which is strongly oxidising, an important property of a cathode material in a battery. These ferrate(VI) compounds have formulae such as K2FeO4 or BaFeO4. In operation the iron(VI) is reduced to the more stable iron(III) according to the cell reaction:
2MFeVIO4 + 3Zn -- FeIII2O3 + ZnO + MZnO2
The problem with using iron(VI) compounds before has been their stability. However, the researchers discovered that they were stable for months in KOH if the iron(VI) compounds were free from nickel(II) or cobalt(II) impurities. The material has a high energy density and a high electrical conductivity so it can be discharged rapidly. The cathode is also compatible with nickel hydride anodes and shows some degree of rechargeability. It is a long way from laboratory to supermarket, but we may well see 'super-iron' batteries on the shelf in the next millennium.
(Science 285, 1039, 1999)
******
Thinkpad T40 = 6 hours (Score:2)
Cheater... (Score:2)
battery? shamattery! (Score:2, Funny)
More crap from another blog (Score:5, Insightful)
Battery hype has been around for a century. If you've followed the electric car industry, you're familiar with the frustrations of listening to new battery technology claimants. A basic problem is that more powerful battery technologies tend to require more reactive materials, ones further from the center of the electromotive scale. Lithium has been made to work, but it took a long time and a few laptop fires. Sodium-sulfur batteries seem to be too dangerous. There are some workable chemistries, like silver-cadmium, that require overly expensive materials. Thus, there are some high-power battery technologies which have been successfully demonstrated but aren't going mainstream. The mPhase people aren't even at that point.
This is a consistent problem with Piquepaille's blog. He comes across some overhyped press release and writes it up as a "technology trend". He seems to want to be the next George Gilder, who you may remember as a pundit from the days of dot-com hype.
No changes in battery Life???? (Score:2, Insightful)
You're looking in the wrong places (Score:4, Funny)
Last year I had an 800mhz AMD Duron Sony Vaio that lasted about 45 minutes on battery (if I was lucky).
This year I have an iBook G4 with a battery that lasts 4-7 hours. I'd call that a performance improvement.
Re:You're looking in the wrong places (Score:2, Insightful)
Power sources are improving (Score:4, Insightful)
Back in 1942... (Score:5, Interesting)
The Exide mas was asked if they could increase the charge density somehow, the response was immediate, "Yes."
The spook was somewhat nonplussed, as this was not the answer he was expecting, so he then asked if Exide could do it, why didn't they?
This response was also immediate.
"We sell more batteries."
That was 60 years ago, why does anyone think anything has changed?
(esp when detroit is now producing SUV's that get worse mileage than 50 year old 500 cubic inch big block engined cars)
battery life can be markedly improved (Score:5, Insightful)
When I was at U-Mass lowell, we had a guest speaker who worked with search and rescue robotics and was trying to start a small company to sell them to fire departments. He used dewalt drill batteries, in 18v configurations.
being in a robotics course ourselves, a lot of our questions focused on them. Being expensive and shortlived, the speaker explained that the newest line of dewalt drills had some sort of mechanism to 'recognize' different batteries. to keep the life long-lasting and decrease wasted charge time, the charger would be able to tell how many charges it had given this battery, would know when to stop, and would know enough not to 'hot charge' a battery that just came off of use.
of course, some other people want to do away with storing potential electricity alltogether, given the large amount of weight/stuff you need to store it. that's where stuff like fuel cells come in. store a fuel that we can easily convert to electricity instead, that might be lighter and take up less space and might hold more potential electricity.
Well, why not... (Score:4, Funny)
environment? (Score:3, Funny)
I miss the good old days, when you could chuck a battery into the woods and melt the skin off passing wildlife. Yeah, those were the days.
Work on the other side of the problem. (Score:5, Interesting)
For truly low powered processors, we need asynchronous logic. Current CPUs, when nothing is happening, close down bits that they think are not being used and slow their clock rate. This reduces, but does not eliminate, power consumption. Asynchronous logig, on the other hand, whenit is not doing anything - does nothing. Nothing clocks, nothing changes state.
Then the displays. We need ambient light displays, as opposed to self-illumiated ones. We don't usually sit in the dark, to why have a dispalay that assumes we do? Some of these are being sold as "digital paper" or similar. Unlike CRT, LCD or Plasma, when the display is not changing, they consume no power. Only B/W so far, I believe - but I would rather a B/W display I can read than a ulesless lump with a flat battery.
Which means that we need to rethink the OS. The steady state of the screen must be still. We are fattening ourselves up on animated this and that. We need to rethink this. We need to research hoe to make the pointer flip the minimum number of pixels as it moves. A flashing cursor is a waste of energy: find better ways of indicating the current position. Maybe WYSIWIG is too expensive: go back to type-and-preview: only a single character changes for each keystroke, so only about 30x20 pixels need redrawing. And scroll by a few lines at a time, so that you don't have to scroll often.
Heat... (Score:2)
Stupid entropy.
benefits of lead acid (Score:5, Informative)
1. Lead acid is somewhat forgiving, and can theoretically last forever if you are mostly careful not to do a deep discharge. Most other designs have a finite number of cycles.
2. Price. It's an old technology. Car manufacturing has driven the development, and you are pretty certain to get a functional battery that does what it's supposed to.
There are two downsides.
1. No deep discharge. Once the voltage starts to drop a little, you better get back home to recharge or the battery will be dead (not sure of the chemistry involved.)
2. Low temperature functioning. Lead acid batteries cool down as you draw current from them. If you take them out for a midnight ride in the winter, you will find your voltage dropping much quicker than you expect. NiCads actually generate heat as you discharge them, and so can keep functioning even in freezing conditions.
As I understand, for these second two reasons, most commerically available bicycle lights are now NiCad. This should mean you can go for a three hour bicycle ride and draw twenty watts of light. However, it does mean that you have to replace the batteries every other year or so (depending on usage.)
Similar technology being used elsewhere (Score:3, Interesting)
Batteries that double as fuel cells (Score:2, Interesting)
Their RPC cells seem to have a power and convenience advantage [evionyx.com] over almost everything else.
My math doesn't agree with his... (Score:3, Insightful)
"We can get to the point where the initial cost can be competitive with the electric grid," McGahn told UPI. "If we had a 10-mile-by-10-mile square, we could power the country."
Excuse me? Really? I have a hard time believing that there aren't a couple power utilities snapping this up if it's true. I suspect this is at best a bit of hyperbole. And as such have to question the reliability of a reporter that would print such a statement unchallenged.
But maybe I'm just cranky at having an 8 pound laptop with half the weight being battery...
Re:My math doesn't agree with his... (Score:3, Informative)
The actual number is 100 miles squared, which too many people take as 100 square miles. Not the same. (In fact, I have been personally misquoted as saying the latter.
That said, it's pretty clear why the utilities haven't done it...Space has not been the issue with solar panels for 15 years now. Plenty of unused roof space, brownfields, etc., etc.
It's cost...here's your math.
Bulk solar panels go for ca. $2.90 / Watt anymore, making for a residential turnkey full system cost of a little over $6.50 (say $