Waste Heat Could Double Battery Life
December 1, 2009 at 2:47 am | In Uncategorized | Leave a CommentTags: Waste
When we utilize any gadget or means of comfort we know that these devices consume energy. But the energy is not utilized by devices. Some of the energy is lost in the form of friction or heat. For example when we are exploiting the power of computer processor chips, car engines or electric power plants there is a necessity of getting rid of excess heat otherwise the equipments will not perform at their optimal level. Now researchers are thinking about using this waste energy. Peter Hagelstein is the co-writer of this concept and an associate professor of electrical engineering at MIT. His paper was published in the November 2009 issue of the Journal of Applied Physics.
If this wasted energy is cleverly harnessed we might double the use of cell phones talk time without plugging them again and again for recharging. The same could be the case with our laptops; we don’t have to recharge them frequently and their wear and tear could be reduced too. The overworked and overloaded poor power plants can shell out more power if their wasted heat energy can be utilized.
Hagelstein is of the view that current solid-state devices that utilize excessive heat and convert it into electricity are not very efficient. He is working with his graduate student Dennis Wu as part of his doctoral thesis to find out a practically dependable heat energy converter that doesn’t carry forward its predecessor’s disadvantages. They are gunning for a realistic technology that could come to achieving the theoretical limits for the efficiency of such conversion.
Theory postulates that such energy conversion can never go over a precise value called the Carnot Limit. Carnot Limit was established in 19th-century. It is a formula for determining the utmost efficiency that any machine can achieve in converting heat into work. But the fact is in practice we have only achieved about one-tenth of that limit. Hagelstein working in close association with Yan Kucherov carried out experiments by going for a different technology. They have achieved the enviable efficiency as high as 40 percent of the Carnot Limit. Moreover, their statistics exhibit that this new kind of system could ultimately reach as much as 90 percent of that ceiling.
Hagelstein, Wu and others didn’t try to improve upon existing devices. They started afresh without any past baggage. They make use of a very simple system in which power was generated by a single quantum-dot device. That device is a type of semiconductor in which the electrons and holes are very securely restricted in all three dimensions. So they tried to understand all the features of the device. This helped them in understanding better all the aspect of such machine.
Hagelstein says that he doesn’t merely want to convert heat into energy but he wants to achieve this by getting lots of energy in return. He also admits that current technology is available to harness heat power, but with a catch. It is known as high-throughput power. It converts heat from a less efficient system and you get more energy. But this is larger and more expensive system. According to Hagelstein “It’s a tradeoff. You either get high efficiency or high throughput.” But the team found that using their new system, it would be possible to get both at once.
Hagelstein and his team studied a recent paper published by MIT professor Gang Chen carefully. They talked about lessening the gaps between hot surface and the conversion device. They suggested this arrangement as very crucial for improving the output. Gang Chen claimed that heat transfer could take place between very closely spaced surfaces at a rate that is orders of magnitude higher than predicted by theory. The new report admits going a step further that heat can not only be transferred, but converted into electricity so that it can be harnessed.
Robert DiMatteo heads a company, MTPV Corp. (for Micron-gap Thermal Photo-Voltaics). DiMatteo is willing to commercialize Hagelstein’s new idea. He is quite hopeful that the technology developed by his company could yield a tenfold improvement in output power over existing photovoltaic devices. He plans to market this technology next year. At the same time Hagelstein’s work would give the required push and an additional tenfold or greater improvement is possible.
DiMatteo presents his stats and says that worldwide, when we consume fuel or a powerhouse generates electricity nearly 60 percent of all the energy is wasted. This waste is generally in the form of heat. 60% is substantial amount. DiMatteo is now hopeful that this technology could “make it possible to reclaim a significant fraction of that wasted energy.”
Hagelstein is of the opinion, “There’s a gold mine in waste heat, if you could convert it. A lot of heat is generated to go places, and a lot is lost. If you could recover that, your transportation technology is going to work better.”
Sony into EV battery market
November 30, 2009 at 4:05 am | In Uncategorized | Leave a CommentTags: EV, Sony
Sony Corp. has revealed plans to start manufacturing high-capacity lithium-ion batteries, with an eye on the promising global electric vehicle (EV) market.
Sony, which currently manufactures compact lithium-ion batteries, will spend 100 billion yen in the next few years to set up a high-volume production system for high-capacity batteries, according to Sony Executive Deputy President Hiroshi Yoshioka.
There have been several deals between the electronic and automobile industries in producing high-capacity lithium-ion batteries — on which EVs depend for power — such as that between Panasonic and Toyota. With Sony one of the last major electronics corporations to join the race, all eyes are on who will become its partner.
Sony currently manufactures 41 million compact lithium-ion batteries for laptop computers and cell phones every month at six factories in Japan and abroad. Last August, it spent 40 billion yen to reinforce its production capacity at two domestic plants, with plans to increase production to 74 million batteries a month by the end of October. Plans for increased production were halted, however, when business performance rapidly declined after the Lehman Shock last fall.
However, “the world economy is on its way to recovery,” according to Yoshioka, leading Sony to decide not only to reinstate the investment plans that had been put on hold, but also to begin manufacturing high-capacity lithium-ion batteries, which are used for storage batteries in EVs and solar power generators, hoping to help haul itself out of its rut.
In addition to the billions of yen that will be invested in the new operations, Yoshioka revealed that the company is already taking other measures, including the assignment of an in-house team responsible for developing high-tech magnetic tape to the battery division.
Asked about potential partners in the automobile industry, Yoshioka seemed confident that options were still available, indicating that Sony is hoping to shop its prototypes to various car manufacturers. “The collaboration of electronics and automobile companies over lithium-ion battery production for EVs is still a relatively new phenomenon,” he said. “And while we are considered late in entering the market, we still have plenty of chances to have our case heard.”
Utility scale liquid batteries
November 28, 2009 at 1:53 am | In Uncategorized | Leave a CommentTags: liquid
One of the problems with large scale renewable energy is the cost of batteries for storing electricity. 
Storage is needed because wave, wind, and solar energy all have down times when the water is calm, no wind blows, and when the sun goes down. The cost of batteries for utility scale projects is extremely expensive. MIT professor Donald Sadoway has come up with a way to counter those problems by building a liquid battery.
Sadoway’s batteries are different from any other battery in a number of ways. First, all of the components of the battery are liquid. Some batteries do have one component that is liquid but not the entire battery. Secondly this battery is not intended for use in small electrical devices or cars. Third, this battery is designed to be stationary and very large in order to handle utility scale renewable energy storage. Lastly, the batteries will use low cost easy to find metals.
Because storage devices used by utilities are never transported or used by consumers, many safety features won’t be required. For instance the battery doesn’t need to be “crash worthy” or “idiot proof”. Small batteries won’t be linked together to create enough storage. Instead this battery will be built large enough to handle the amount of electricity that needs to be stored by utility size projects.
The battery uses two liquid metals (not disclosed for patent reasons) and a layer of salt as components. Because the metals must be kept in a liquid state, the entire battery is kept at the very high temperature of 700 degrees Celsius. Keeping large scale versions at this temperature won’t be a problem because of the amount of electricity going in and out of the battery will be enough to sustain the temperature. For the smaller models used in the lab for testing, an outside heater must be used.
In order to bring the cost of renewable energy down to a competitive level with fossil fuels, Sadoway’s batteries must do more than just use cheap abundant materials. He has said that his batteries “must be cheap to build, cheap to maintain, last a long time with minimal maintenance, and store enormous amounts of energy.”
The funding for Sadoway’s research comes from several sources: ARPA-E (Advanced Research Projects Agency, Energy), the Deshpande Center and the Chesonis Family. The French oil company Total has partnered with MIT to develop a liquid battery that would be used in homes or other buildings.
Sadoway is currently testing different combinations of metal alloys to find which ones work the best together. After the optimum metal alloy components are found there are still several other pieces of the battery that must be developed and tested such as “how to design and build the necessary containers, electrical control systems, and connections.”
Developing utility scale cost effective batteries is something of a crusade for Sadoway. As he says, “I’m not doing this because I want another journal publication. It’s about making a difference. It’s an opportunity to invent our way out of the energy problem.”
11 Tips for Black Friday Shopping
November 26, 2009 at 4:01 am | In Special edtion | Leave a CommentTags: Black Friday, Shopping
Black Friday falls on the day after Thanksgiving and has earned the reputation of being the busiest shopping day of the year. The name was adopted from an accounting term – red ink denotes a negative profit margin, where as “in the black” denotes a positive profit margin. Many retailers make or break their sales goals between Thanksgiving and Christmas, with the season kicking off on the Friday after Thanksgiving, hence the name “Black Friday.”
1. Check Out the Ads:
Your local Thanksgiving Day newspaper will be stuffed like your Thanksgiving turkey with ads, coupons, and circulars. This will be your number one source to local Black Friday savings. It will also help you organize your day to maximize savings, since many stores offer special discounts that are time specific. Example: Receive an extra 10 percent off if you shop before 11 a.m.
2. Do Your Research Before Friday:
If you are hoping to scoop up a deal on Friday on a big-ticket item, go ahead and get your research out of the way as soon as possible. A bad product is a bad deal no matter how cheap it costs. Being knowledgeable about the products you want to buy will help you avoid being sucker-punched with loud advertising for poor products. About.com is chocked full of buying advice on a wide variety of products from professionals who have the knowledge to help you make good decisions.
3. Compare Prices:
For items that are available at a lot of retailers (toys, electronics), make sure you know what things should cost by doing some pricing ahead of time at places like PriceGrabber. Don’t assume the first sale price you come across is the best. Before you head to the stores, see if you can avoid the crowds and get the same deal (or better) online, as well. You may be able to shop for most of what you need before the shops even open on Friday morning.
4. Look for Early Bird Shopper Discounts:
The Early Bird Shopper will be the real winner on Black Friday. Stores offering early-day shopper specials usually run the deals from 5 a.m. until 11 a.m. and with no “rain checks,” which means once they run out of the products, you are out of luck. Scanning the ads and routing your trip based on your buying priorities will be important with the time-sensitive deals that will be offered.
5. Beat the Crowds with Night Owl Discounts on Thanksgiving:
Internet shoppers can beat the early birds by shopping online in the pre-dawn hours of Black Friday. Many retailers will be posting their Black Friday specials, which can be ordered online and picked-up at your local store. Special “Web only” deals will also be available starting as early as Thanksgiving eve. Many of the the aggressive outlet malls and factory stores will be opening Thursday at midnight, with early bird promotions in hopes of capturing your dollars before the competition has opened.
6. Bring the Ads:
Many stores offer a “lowest-price” guarantee; however you may be required to produce a copy of the exact product being advertised for less. Most local retailers will not meet Internet prices even when the product is advertised on the same company’s website, but it cannot hurt to try. Print the Web page that details the product and shows the advertised price. It may give you additional bargaining power and push the sales person into waiving other charges such as assembly fees.
7. Make a Plan
For those easily tempted by the word “sale,” Black Friday can spell trouble for your wallet – unless you head into the day with a game plan. Make a detailed list of whom you need to shop for, and how much you have to spend on each person, before you head to the mall. Better still, come up with a specific shopping list or, at the least, some general gift ideas for each person so you aren’t wandering aimlessly in the throngs of shoppers. Figure out which stores you need to shop at, and decide what order you’ll hit them to maximize time.
If you are searching for any hard-to-find items, be sure to head to those retailers first.
8. Know the Store Policies:
Knowing the store policies on returns can help you determine where to buy. A previous trend of extending “return days” during the holidays is being seen less this year. Many retailers are including restocking fees and shorter return deadlines. Almost all of the major retail chains have clamped down on requiring receipts for returns and exchanges, and many keep a database of individuals who tend to abuse return policies. If you get onto an “abuse” list, prepare yourself to be turned down.
9. Ask for Gift Receipts:
Gift receipts generally include a description of the item purchased but do not disclose the price paid. Including gift receipts inside the gift box will make returns or exchanges easier for the gift recipient. Without proof-of-purchase, the recipient may be turned down for returning or exchanging the item or risk receiving an exchange for the current selling price of the item.
Since many retailers begin permanently slashing prices as soon as Black Friday is over, the difference between what you pay for a gift during December and what it sells for in January can be significant. Including a gift-receipt should help insure a hassle-free return experience for gift recipients.
10. Saying “Charge It” Can Pay Off
Obviously, there is no bargain in running up high credit card bills and paying big interest rates, however, with proper spending disciplines intact, using the right charge card can be of value to consumers. Many credit card companies entice consumers with free benefits, which include extended free warranties, return protection and sale price protection.
Warranty Coverage – Your credit card company may offer to double or triple a manufacturer’s warranty for free on a product you purchase – a good option instead of purchasing a service contract that costs money and has a shorter duration period.
Return Protection – A credit card company may guarantee a refund on a product up to 90 days where as the store may not. This is becoming particularly more important as retailers stiffen the allotted return days.
Sale Price Protection – Some of the credit card companies will offer this protection and refund you the difference if a product you buy is marked down further than the price you paid within a certain time frame (usually 60 days).
11. Don’t Feel Like You Have to Shop
Sure, if you get in line at midnight with a hundred other brave souls, you might get your hands on a seriously marked down flat screen, but most of the deals will stick around after Friday. That means you don’t need to feel bad about skipping the mad dash to mall. If enough of us stay home, in fact, the subsequent bargains may be even better.
An enormous amount of advertising, locally and online, can be confusing and nearly paralyzing to the Black Friday bargain hunter. To maximize the benefits of hitting the stores on a day where there are big crowds and a better deal around every corner, developing a plan and doing preliminary research will help insure that the day is a shopping success.
Harnessing Waste Heat Could Double Battery Time
November 26, 2009 at 3:42 am | In battery news | Leave a CommentTags: Harnessing, Waste Heat
In everything from computer processor chips to car engines to electric powerplants, the need to get rid of excess heat creates a major source of inefficiency. But new research points the way to a technology that might make it possible to harvest much of that wasted heat and turn it into usable electricity.
That kind of waste-energy harvesting might, for example, lead to cellphones with double the talk time, laptop computers that can operate twice as long before needing to be plugged in, or power plants that put out more electricity for a given amount of fuel, says Peter Hagelstein, co-author of a paper on the new concept appearing in November in the Journal of Applied Physics.
Hagelstein, an associate professor of electrical engineering at MIT, says existing solid-state devices to convert heat into electricity are not very efficient. The new research, carried out with graduate student Dennis Wu as part of his doctoral thesis, aimed to find how close realistic technology could come to achieving the theoretical limits for the efficiency of such conversion.
Theory says that such energy conversion can never exceed a specific value called the Carnot Limit, based on a 19th-century formula for determining the maximum efficiency that any device can achieve in converting heat into work. But current commercial thermoelectric devices only achieve about one-tenth of that limit, Hagelstein says. In experiments involving a different new technology, thermal diodes, Hagelstein worked with Yan Kucherov, now a consultant for the Naval Research Laboratory, and coworkers to demonstrate efficiency as high as 40 percent of the Carnot Limit. Moreover, the calculations show that this new kind of system could ultimately reach as much as 90 percent of that ceiling.
Hagelstein, Wu and others started from scratch rather than trying to improve the performance of existing devices. They carried out their analysis using a very simple system in which power was generated by a single quantum-dot device — a type of semiconductor in which the electrons and holes, which carry the electrical charges in the device, are very tightly confined in all three dimensions. By controlling all aspects of the device, they hoped to better understand how to design the ideal thermal-to-electric converter.
Hagelstein says that with present systems it’s possible to efficiently convert heat into electricity, but with very little power. It’s also possible to get plenty of electrical power — what is known as high-throughput power — from a less efficient, and therefore larger and more expensive system. “It’s a tradeoff. You either get high efficiency or high throughput,” says Hagelstein. But the team found that using their new system, it would be possible to get both at once, he says.
A key to the improved throughput was reducing the separation between the hot surface and the conversion device. A recent paper by MIT professor Gang Chen reported on an analysis showing that heat transfer could take place between very closely spaced surfaces at a rate that is orders of magnitude higher than predicted by theory. The new report takes that finding a step further, showing how the heat can not only be transferred, but converted into electricity so that it can be harnessed.
A company called MTPV Corp. (for Micron-gap Thermal Photo-Voltaics), founded by Robert DiMatteo SM ‘96, MBA ‘06, is already working on the development of “a new technology closely related to the work described in this paper,” Hagelstein says.
DiMatteo says he hopes eventually to commercialize Hagelstein’s new idea. In the meantime, he says the technology now being developed by his company, which he expects to have on the market next year, could produce a tenfold improvement in throughput power over existing photovoltaic devices, while the further advance described in this new paper could make an additional tenfold or greater improvement possible. The work described in this paper “is potentially a major finding,” he says.
DiMatteo says that worldwide, about 60 percent of all the energy produced by burning fuels or generated in powerplants is wasted, mostly as excess heat, and that this technology could “make it possible to reclaim a significant fraction of that wasted energy.”
When this work began around 2002, Hagelstein says, such devices “clearly could not be built. We started this as purely a theoretical exercise.” But developments since then have brought it much closer to reality.
While it may take a few years for the necessary technology for building affordable quantum-dot devices to reach commercialization, Hagelstein says, “there’s no reason, in principle, you couldn’t get another order of magnitude or more” improvement in throughput power, as well as an improvement in efficiency.
“There’s a gold mine in waste heat, if you could convert it,” he says. The first applications are likely to be in high-value systems such as computer chips, he says, but ultimately it could be useful in a wide variety of applications, including cars, planes and boats. “A lot of heat is generated to go places, and a lot is lost. If you could recover that, your transportation technology is going to work better.”
Nissan plans to boost EV
November 25, 2009 at 6:04 am | In battery news | Leave a CommentTags: EV, Nissan
President Barack Obama has set an ambitious goal of putting at least 1 million battery-powered cars on the road by the middle of the coming decade.
Many in the auto industry have charitably called that target ambitious. Others are less polite. But while it may be a difficult goal, Nissan CEO Carlos Ghosn is among those who believe the public may get charged up by the switch to electric power.
To get there, however, he stresses that some of the industry’s basic business models may have to be rethought to reflect the new world of electric propulsion.
Ghosn was in Los Angeles recently for the start of Nissan’s “Zero Emissions Tour,” a 22-city road show that will lead up to the launch next year of the first of four battery-electric vehicles, or BEVs, the Japanese maker plans to launch in the next few years.
The Leaf is a 5-seat sedan similar in size to the subcompact Versa, but it replaces the current model’s gasoline engine with an 80 kilowatt electric motor with about 110 horsepower that draws its power from a lithium-ion battery pack.
While Ghosn is quick to proclaim that battery propulsion “will change the industry,” he also acknowledges that to win over buyers, tomorrow’s BEVs will need to be “affordable, … cool, attractive and fun to drive.”
On the positive side, electric motors develop maximum tire-spinning torque the moment they start to turn, and a prototype Leaf launched fast enough to throw a passenger back deep into the seat. The design of Nissan’s first battery car is as distinctive as Toyota’s gas-electric hybrid Prius, though Leaf program manager Hideaki Watanabe said Nissan opted against a “spaceship-style design” to avoid alienating more traditional buyers who might otherwise want an emissions-free car.
Nissan is betting there is a core group of buyers who will opt for a vehicle like the Leaf to assuage their “environmental guilt.”
But to make the technology sustainable as a business will require reaching into the mainstream. That’s not easy. Even conventional hybrids, such as the Prius, Honda’s Insight and the Ford Fusion Hybrid, are struggling to garner more than 2 to 3 percent of the U.S. automotive market.
There is no hard data, but it’s estimated that there are only a few thousand BEVs on the road now, not including hybrids, which also have a gasoline engine. Hybrids have had some initial success in part because they don’t have some of the limitations of the pure battery car, such as limited range, long charging times and high costs, mostly for their batteries.
Because of pricey lithium-ion, or LIon, technology, General Motors is expected to charge more than $40,000 for its extended-range electric vehicle, the 2011 Chevrolet Volt. A special $7,500 federal tax credit will bring the price down to the mid-$30,000 range, still a sizable chunk for a compact sedan.
Ghosn suggests the Leaf will be priced no more than “2 to 3 percent” more than a comparable gasoline vehicle, which would mean $25,000 or less, depending on final equipment levels.
How can Nissan afford to make such a deal without going deeply in debt on each vehicle? The sticker price will cover just the vehicle itself, and not the battery, which will be leased separately, Ghosn said. The monthly fee will be based on what it would cost to fuel up a comparable, gasoline-powered vehicle to run about 15,000 miles annually which, depending upon your assumptions about future oil prices could run $200 to $400.
In its initial incarnation, the Leaf is expected to deliver up to 100 miles on a charge. Actual mileage may vary, depending on driving style and driving conditions. That may not sound like much but research shows that up to 70 percent of American drivers drive less each day than the 40-mile battery range of Volt and more than 80 percent never reach 100 miles in a day.
That doesn’t completely resolve so-called “range anxiety,” the fear of needing a little bit more in an emergency. To help address that, Nissan has been forming a variety of partnerships with the likes of Project Better Place, which is setting up a network of quick charging stations in Israel, and even special facilities that can swap a discharged battery for a fresh one in no more time than it normally takes to gas up.
Here in the States, Nissan recently inked a partnership with Texas-based Reliant Energy, which will provide fast 220-volt chargers to Leaf buyers and set up quick-charge facilities that could be used at offices or on the road. Nissan says one system under development would give an 80 percent charge in less than 10 minutes.
(Via)
‘Hybridisation’ tech to quintuple battery life
November 24, 2009 at 1:14 am | In battery news | Leave a CommentTags: Hybridisation
Most of us these days find battery life an annoying issue, as our increasingly puissant personal gadgetry uses juice faster and faster. Few, however, find batteries as troublesome as modern-day soldiers do – burdened as they are with lasers, optics, radios, monocle displays and other electronic paraphernalia.
Adding insult to injury for the overburdened modern grunt – who must also hump a crippling load of armour, weapons, ammo and water – is the fact that batteries generally don’t live up to their full potential in actual service use. In fact, according to the renowned Pentagon brainiac-breeding bureau DARPA, it’s common for war-ware to achieve endurance of “as little as 20% of theoretical capability. This operational inefficiency increases the number of batteries soldiers must carry in the field”.
What’s the use of inventing brilliant new technology for soldiers if they can’t lift all the batteries needed to keep it running, after all? (DARPA was behind much of the nightsight tech now commonly found attached to soldiers’ helmets and weapons, for instance).
Thus it is that the military boffins have decided to launch a new project, named Limits Of Thermodynamic Storage (LOTS) of Energy. This isn’t intended so much to produce radical new energy storage technologies, as to wring all the juice out of existing battery kit. According to DARPA:
The program seeks to address inefficiencies in energy extraction by developing technologies that are capable of delivering the full expected run time out of a [state of the art] portable energy source.
All possible approaches, and combinations of approaches, will be considered including, but not limited to:
• hybridization via discrete components within the form factor of the energy source (e.g.: packaged electrochemical capacitor plus packaged battery)
• innate hybridization via development of multi-functional electrochemical cells (e.g.: a cell with both capacitive and faradaic energy storage functions)
• performance optimization via use of power management circuits
The idea is that initial LOTS-o-Energy devices will use the military X590 form factor, which is essentially a box which can hold ten D-cells. DARPA’s chosen contractor will make such a box which will contain batteries as well as the new magic that causes them to actually give up all their juice, rather than spuriously flatlining while still crammed with energy as they now tend to.
Of course there are many other ways such kit could be useful. One of the most common problems in engineering is getting a prime mover or energy source to deliver that energy to a task efficiently. DARPA say that X590 goodened-up batteries are just the beginning: they would expect to use the same miracle-tech with other power sources such as fuel cells or stirling engines.
As with some other DARPA notions, this one has excellent potential to benefit all of humanity as well as just US troops. Well, that part of humanity which likes gadgets, anyway.
(Via)
Battery charger controllers keep efficiency high
November 23, 2009 at 7:08 am | In battery news | Leave a CommentLinear Technology has introduced the LTC4012, LTC4012-1 and LTC4012-2 – fast-charge 4A-capable high-efficiency 
switchmode battery charger controllers for multiple battery chemistries.
The LTC4012 supports Li-Ion/Polymer, NiMH, NiCd and sealed lead acid battery chemistries in single and multi-cell configurations.
It also offers an adjustable battery termination voltage, while the LTC4012-1 and LTC4012-2 utilise a programmable internal resistor divider to charge from 1-4 series Lithium cells at multiples of 4.1V and 4.2V respectively.
All devices feature a wide output voltage range of 2V to 28V.
The devices’ analogue Infet control means there is no need for an external blocking diode at the power input, thereby increasing efficiency and reducing the solution footprint.
In addition, AC adapter current limiting maximises the charge rate for a given fixed input power level, allowing the end-product to operate at the same time the battery is charging without complex load management algorithms.
The ICs operate at input voltages from 5V to 28V and are intended for applications including portable computers, portable instruments and battery backup systems.
The LTC4012/-1/-2’s synchronously rectified, buck-switching topology drives all in-channel Mosfets and enables efficiencies >90 per cent at 3A.
Final float voltage accuracy is specified at +/-0.5 per cent and charge current is programmable with an accuracy of +/- 4 per cent.
The ICs quasi-constant frequency PWM architecture guarantees no audible noise operation and minimises filtering needs, while the 550kHz operating frequency allows the use of small inductors and capacitors.
Improved non-overlap control is said to keep efficiency high as external power FET turn-on/off times may vary with temperature and supplier.
The LTC4012/-1/-2 consumes <30uA without a DC power input, increasing battery runtime in portable applications.
For safety and autonomous charge control, the ICs include battery float voltage over-voltage protection, reverse charge current protection, charge current monitoring, soft start, AC adapter present indication, and current limit indication.
The LTC4012/-1/-2 are housed in a compact 20-lead, low-profile (0.75mm) 4 x 4mm QFN package.
They are guaranteed for operation from 0C to 85C ambient temperature.
(Via)
New material improves Li-ion battery safety
November 21, 2009 at 1:36 am | In battery news | Leave a CommentTags: STOBA
Taiwan’s Industrial Technology Research Institute (ITRI) has unveiled STOBA (self-terminated oligomers with hyper-branched architecture), which it claims to be the first material technology to enhance the safety of Li-ion batteries.
Li-ion batteries, the power source for many consumer electronic devices, including cell phones, laptops, MP3 players, cameras, and hybrid and electric cars, are susceptible to overheating, which can cause fires and explosions.
In 2008, 310 crore Li-ion batteries were produced globally, a 10 per cent growth from 2007, which magnifies the environmental footprint and safety concerns Li-ion batteries present when used in consumer electronics and electric cars. The U.S. Consumer Product Safety Commission confirmed that product recalls involving Li-ion batteries occur every year. In fact, in May of 2009 alone, 70,000 notebook computers were recalled by a major manufacturer, and in 2006, another major brand recalled over 40 lakh notebooks due to Li-ion battery malfunctions.
To meet the growing demand for safer lithium batteries, ITRI has developed STOBA. By integrating a nanograde polymer, which forms a protective film much like a nanograde fuse, into the Li-ion battery, a locking effect is generated when the battery encounters excessive heat, external impact or piercing and interrupts the electrical and chemical action, preventing explosions that threaten consumer safety.
STOBA has passed mandatory shorting and piercing experiments conducted in 2008 and 2009 by battery manufacturers in Japan and Taiwan. The intensive nail penetration and impact tests confirmed STOBA’s effectiveness in preventing internal shorting and overheating in Li-ion batteries.
Besides its safety features, STOBA also extends the life of the Li-ion battery by about 20 per cent, or an additional two years, due to the nanograde STOBA film that stabilises the electrode material at high temperatures (55° Celsius).
“The creation of the STOBA material is a significant breakthrough in Li-ion battery technology. The safety of electronic products will no longer be a concern to consumers,” said Dr. Alex Peng, senior research scientist and deputy general director at ITRI’s Material and Chemical Research Laboratories (MCL). “ITRI will work with lithium battery manufacturers, and leading cell phone, laptop and electric vehicle makers to ensure wide adoption of this technology.”
Led by Peng, R&D of STOBA began in 2004. After years of repeated experiments and adjustments, Peng and his team discovered the nano-grade STOBA material technology. STOBA’s heat-resistant, fair bonding and flexible qualities allow Li-ion batteries to gain redundancy time and reach twelve sigma, which generates the locking mechanism when they short and generate unstable temperatures. ITRI has applied for 29 patents for the STOBA technology in five countries including the United States, Taiwan, Korea, China and Japan.
Progress in Betavoltaic Battery Research
November 20, 2009 at 2:41 am | In Uncategorized | Leave a CommentTags: Betavoltaic, Research
Nuclear power has been discarded for decades since the tragic accidents from the 80’s that led to numerous environmental damages in Ukraine and other parts of the world. Still, nowadays there is a trend of reviving nuclear power, to make it 100% safe and to convince people it’s worth investing in it, as an alternative to coal or petrol.
Ithaca, a NY-based company, is starting the production of the so-called “betavoltaics” – sources of nuclear power in the form of small batteries whose charge could last for as long as 25 years. Their technology has been tested by Lockheed Martin, an important military equipment manufacturer. Of course, these batteries will be used to power electrical circuits that protect military planes and missiles from tampering and reverse-engineering.
In the meanwhile, another company, called Widetronix, is trying to implement the nuclear technology into medical-use batteries. Their cells are powered by the decay of a hydrogen isotope called tritium into high energy electrons. Betavoltaic cells such as Widetronix’s use semiconductors to capture the energy in the electrons produced during the nuclear decay of isotopes just like solar cells capture the photons’ energy. Betavoltaic batteries can withstand harsher conditions than chemical batteries do, being available at any environment temperature.
Widetronix’s batteries are made up of a metal foil impregnated with tritium isotopes and a thin chip of the semiconductor silicon carbide, which can convert 30 percent of the beta particles that hit it into an electrical current. “Silicon carbide is very robust, and when we thin it down, it becomes flexible,” says Widetronix CEO Jonathan Greene. “When we stack up chips and foils into a package a centimeter squared and two-tenths of a centimeter high, we have a one microwatt product.” The prototype being tested by Lockheed Martin produces 25 nanowatts of power.Betavoltaics aren’t very powerful. They don’t have nearly enough power to drive a laptop or a cell phone. But their energy density is high: they store a lot of energy in films just micrometers thick and can be made in very small packages. “We’re focusing on places where you need a very long life and energy density,” says Greene.
The risk of using betavoltaics drops as researchers gain more and more experience from using the radioactive material. The only problem still remains their disposal: where are we going to put all the unused batteries, or what are we going to do with the damaged ones? Isn’t this going to affect us? If these questions could be answered with certainty and scientific evidence, I see no reason why we shouldn’t use portable nuclear power everywhere. Until these questions will be answered, I’ll stick to chemical batteries.
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