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Model Forum / Radio Controlled / Air Models / March 2009Lipos that recharge in 10 seconds
This is still in the works, but they say in 2 - 3 years we will be able to get them. http://tech.yahoo.com/news/nm/20090311/tc_nm/us_batteries_3 U.S. engineers find way to build a better battery (Reuters) * Posted on Wed Mar 11, 2009 7:15PM EDT CHICAGO (Reuters) - U.S. engineers have found a way to make lithium batteries that are smaller, lighter, longer lasting and capable of recharging in seconds. The researchers believe the quick-charging batteries could open up new applications, including better batteries for electric cars. And because they use older materials in a new way, the batteries could be available for sale in two to three years, a team from Massachusetts Institute of Technology reported on Wednesday in the journal Nature. Current rechargeable lithium batteries can store large amounts of energy, making them long-running. But they are stingy about releasing their power, making them discharge energy slowly and require hours to recharge. Scientists traditionally have blamed slow-moving lithium ions -- which carry charge across the battery -- for this sluggishness. However, about five years ago, Gerbrand Ceder and a team at MIT discovered that lithium ions in traditional lithium iron phosphate battery material actually move quite quickly. "It turned out there were other limitations," Ceder said in a telephone interview. Ceder and colleagues discovered that lithium ions travel through tunnels accessed from the surface of the material. If a lithium ion at the surface is directly in front of a tunnel entrance, it can quickly deliver a charge. But if the ion is not at the entrance, it cannot easily move there, making it less efficient at delivering a charge. Ceder and colleagues remedied this by revamping the battery recipe. "We changed the composition of the base material and we changed the way it is made -- the heat treatment," Ceder said. This created many smooth tunnels in the material that allow the ions to slip in and out easily. "The trick was knowing what to change," he said. Using their new processing technique, the team made a small battery that could be fully charged in 10 to 20 seconds. Ceder thinks the material could lead to smaller, lighter batteries because less material is needed for the same result. And because they simply tinkered with a material already commonly used for batteries, it could be easily adapted for commercial use. "If manufacturers decide they want to go down this road, they could do this in a few years," Ceder said. One glitch, Ceder said, would be handling the extra surge of power. "All of the wiring has to get beefed up," he said. (Editing by Maggie Fox and Cynthia Osterman) .SNIP >to change," he said. > [quoted text clipped - 12 lines] > One glitch, Ceder said, would be handling the extra surge of power. "All > of the wiring has to get beefed up," he said. Yes, and when it's built into a stack for a car, you will need 10,000 amps to charge the car in 20 seconds.... and cables about 100mm diameter? How big will the plug be? > .SNIP > [quoted text clipped - 20 lines] > :-) Not to mention what the actual weight and conversion efficiency of cells capable of being slammed that hard is.. However three minute charge times would be similar to refuelling a gas engine. That might be a better and more practical target . I saw my first Tesla yesterday. Bloody fast. Must have been doing about 80mph. I guess it was on a test run as it was only 10 miles from the Lotus factory... > > .SNIP Here is a bit more (and different) info. http://www.theregister.co.uk/2009/03/12/fast_charge_battery_bubble_stab/ > .SNIP > [quoted text clipped - 18 lines] > to charge the car in 20 seconds.... and cables about 100mm diameter? How > big will the plug be? On the other hand, in a cell phone I can see the advantage, along with all other portable devices. ... > However, about five years ago, Gerbrand Ceder and a team at MIT > discovered that lithium ions in traditional lithium iron phosphate > battery material actually move quite quickly. ... > Using their new processing technique, the team made a small battery that > could be fully charged in 10 to 20 seconds. ... Hi! They used a LiFePO4 based accumulator: 11 March 2009 Lithium batteries charge ahead. Researchers demonstrate cells that can power up in seconds: http://www.nature.com/news/2009/090311/full/news.2009.156.html?s=news_rss Qoute: "... That seemed to be the case for lithium iron phosphate (LiFePO4), a material that is used in the cathode of a small number of commercial batteries. But when Ceder and Kang did some calculations, they saw that the compound could theoretically do much better. Its crystal structure creates "perfectly sized tunnels for lithium to move through", says Ceder. "We saw that we could reach ridiculously fast charging rates." ... The authors helped the ions by coating the surface of the cathode with a thin layer of lithium phosphate glass, which is known to be an excellent lithium conductor. Testing their newly-coated cathode, they found that they could charge and discharge it in as little as 9 seconds. ..." Glenn | Testing their newly-coated cathode, they found that | they could charge and discharge it in as little as 9 seconds. People thought 30C was a high discharge rate ... Now we've got (do some math) 400C discharge (and charge) rates? Whee! Short circuits get even more exciting!  SignatureDoug McLaren, dougmc@frenzied.us All that glitters has a high refractive index. > | Testing their newly-coated cathode, they found that > | they could charge and discharge it in as little as 9 seconds. [quoted text clipped - 4 lines] > > Whee! Short circuits get even more exciting! or fly/drive/sail some minutes... charge 9 seconds... fly/drive/sail some minutes... ... Remember to reserve some charge to start car! ;-) Glenn ... | fly/drive/sail some minutes... | | charge 9 seconds... | | fly/drive/sail some minutes... Well, even if 9s charge times aren't practical, batteries that can tolerate a 400C rate will be able to handle a 20C discharge rate with an almost zero voltage drop ... It will be a good thing, even if you can't use it all. And besides, if you can't charge at 400C ... even 20C would be very nice -- fly again in 3 minutes. SignatureDoug McLaren, dougmc@frenzied.us Television. Teacher, mother, secret lover. --Homer Simpson Sorry ol buddy, but all of the parameters that facilitate faster charge levels also deprecate capacity and internal resistance. Battery/cell design 101. No free lunches I'm afraid. SignatureRed S. Red's R/C Battery Clinic http://www.rcbatteryclinic.com Check us out for "revolting" information. > ... > [quoted text clipped - 11 lines] > if you can't charge at 400C ... even 20C would be very nice -- fly > again in 3 minutes. I think Doug meant that as the batteries have the capability even though charging them at their max rate was impractical there would be almost no drop in use. I think this would be correct. Gerry > Sorry ol buddy, but all of the parameters that facilitate faster charge > levels also deprecate [quoted text clipped - 15 lines] >> if you can't charge at 400C ... even 20C would be very nice -- fly >> again in 3 minutes. | I think Doug meant that as the batteries have the capability even though | charging them at their max rate was impractical there would be almost no | drop in use. I think this would be correct. I imagine that Red understood me correctly. However, any battery that can be charged (or discharged -- they said that too) at 400C must have an extremely small internal resistance. Yes, you generally do have a series of tradeoffs involved in designing a battery -- you can maximize capacity at the expense of intenal resistance, for example, and that's quite popular with consumer NiMH AA cells. And perhaps they have to give up a lot of capacity to get something that can do 400C, but they still must be on to something. But even if the 400C battery had half the capacity per weight/size of a 30C cell it would still be very useful for certain applications. R/C related, that would be great for a competition limited motor run glider -- 30s of power, then the motor gets turns off. So you put in a battery only big enough to run the motor for say 60s, keeping weight down. Or in a hybrid car, you could have a tiny battery pack, perhaps only big enough to run the motor for 60s -- enough to save the energy from one braking and accelerate the car back up to speed again. I always figured that it would be ultracapacitators that would fit that niche first (they still need some work in the capacity arena however) but maybe not. |> Sorry ol buddy, but all of the parameters that facilitate faster charge |> levels also deprecate |> capacity and internal resistance. Battery/cell design 101. No free |> lunches I'm afraid. SignatureDoug McLaren, dougmc@frenzied.us Our OS who art in CPU, UNIX be thy name. Thy programs run, thy syscalls done, In kernel as it is in user! > | I think Doug meant that as the batteries have the capability even > though | charging them at their max rate was impractical there would be [quoted text clipped - 23 lines] > niche first (they still need some work in the capacity arena however) > but maybe not. Or store the energy from one braking and then spin it out slowly to the main pack. Of course, "one braking" is different in Chicago than it is coming off the summit of the Rockies. Signaturehttp://www.wescottdesign.com >> | I think Doug meant that as the batteries have the capability even >> though | charging them at their max rate was impractical there would be [quoted text clipped - 29 lines] > Of course, "one braking" is different in Chicago than it is coming off > the summit of the Rockies. Interesting, could you re-charge your hybrid car on the way down IF you made it to the summit? mk >>> | I think Doug meant that as the batteries have the capability even >>> though | charging them at their max rate was impractical there would [quoted text clipped - 36 lines] > made it to the summit? > mk If it's a _Hybrid_ car you'd need to convert CO2 and water vapor back to gasoline, which would be hard. In theory, if it were all electric you should be able to recover a good deal of the charge on the way down, but in practice you'd be limited both by the battery's ability to absorb charge that quickly. Even if you could recover the power from the motor, that 'good deal of the charge' is never going to be more than 50%, and will probably be more like 10-20. Signaturehttp://www.wescottdesign.com ... >> Interesting, could you re-charge your hybrid car on the way down IF you >> made it to the summit? [quoted text clipped - 8 lines] > could recover the power from the motor, that 'good deal of the charge' is > never going to be more than 50%, and will probably be more like 10-20. Hi Tim and Doug On the way down hill you simply charge stationary LiFePO4-accu via 9 seconds long eletrical road rails. The energy can be stored, until another hybrid/electrical-vehicle needs energy to climb the hill, which is supplied via 9 seconds long eletrical rails on the other side of the road. The eletrical rails could be near houses or pumped-storage hydroelectricity: http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity /Glenn > .... >>> Interesting, could you re-charge your hybrid car on the way down IF you [quoted text clipped - 25 lines] > > /Glenn Hi Tim and Doug (follow-ups will default be sent to nntp://rec.models.rc.air ) If a electrical/hybrid vehicle can store 15kWh and weights 1000 kg and is used on an earthly hill, it will ideally gain/loose the following amount of electrical energy (using http://en.wikipedia.org/wiki/Potential_energy ): deltaE(J)=m*g*deltah <=> deltah = E(J)/(m*g) deltaE(J) = 15kWh*3600J/Wh = 54MJ e.g. deltah = 54MJ/(1000kg*10m/s^2) = 5400 meters. Which means that the vehicle in question, can ideally climb or descend 5,4km before (dis)charging. (unless I have made some sort of error) - Of course - the following will transform some of the gravitational potential energy to heat, noise...: *Wheel friction *Wind turbulence *Snow packing *Mechanical friction *Electrical losses in motor and ESC with regenerative braking ESC: http://en.wikipedia.org/wiki/Electronic_speed_control A dream wheel?: e-traction.com: TheWheel™ - what it is and what it does: http://www.e-traction.com/TheWheel.htm Quote: "...operating at more than 90% energy efficiency...delivers up to 120 KW of direct drive traction at the only place where it matters,.....at the wheel...the braking action is converted back to electrical power. This process is called regenerative braking..." /Glenn | If a electrical/hybrid vehicle can store 15kWh and weights 1000 kg and | is used on an earthly hill, it will ideally gain/loose the following | amount of electrical energy (using ... | deltah = 54MJ/(1000kg*10m/s^2) = 5400 meters. Your math is correct, though I just let google do the heavy lifting for me -- http://www.google.com/search?hl=en&q=15+kWh+%2F+g+%2F+1000+kg+in+meters (15 (kWh / g)) / (1000 kg) = 5506.46755 meters However, 15 kWh is a big battery. I think the energy density for good LiPos is around 540 KJ/Kg? That means your battery pack would weigh around 100 Kg. For the NiMH batteries used in current hybrids, their energy density is about half that, so that's 200 Kg. Also note that 1000 Kg is a small car -- even a Prius weighs more than that, at around 1350 Kg, and that doesn't include fuel, cargo or passengers. And only about 45 Kg of that is battery. Ultimately, I don't think that being able to store 15,000 feet worth of descent in their batteries is really the intent of most hybrids. Instead, they want to be able to store the energy produced by slowing down from 70 mph or so a few times -- which works out to a gain of only about 160 feet for each time. http://www.google.com/search?hl=en&q=0.5+(70+mph)+^+2+%2F+g+in+feet ... but they have to keep a larger battery to keep the charge rate down, and 400C batteries would let them use smaller batteries to keep the weight and cost down. SignatureDoug McLaren, dougmc@frenzied.us `Sir, I protest! I am NOT a merry man!' --Worf, ST:TNG > This is still in the works, but they say in 2 - 3 years we will be able > to get them. [quoted text clipped - 60 lines] > > (Editing by Maggie Fox and Cynthia Osterman) http://www.pcworld.com/article/161116/article.html?tk=nl_dnxnws Yippee! And we will have mini-fuel cells operating on cold fusion to charge them. :-) All in due time grasshopper. SignatureRed S. Red's R/C Battery Clinic http://www.rcbatteryclinic.com Check us out for "revolting" information. > This is still in the works, but they say in 2 - 3 years we will be able to > get them. [quoted text clipped - 59 lines] > > (Editing by Maggie Fox and Cynthia Osterman) |
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