Finally! Ultra Cap / Lithium-Ion Battery CombinationTesting

Ultra capacitors are a better way to store, as electricity, the kinetic energy quickly recoveredwith regenerative braking / suspension systems. Their quick discharge ability then make themsuitable for release of high current to boost acceleration. On the other hand, deep cyclebatteries have greater capacity.Batteries cannot absorb all the power available from regenerative braking. The chemicalreaction is much too slow; more than 50% of this energy is wasted. This blog previously wroteabout energy storage that integrated batteries and super capacitors.Batteries also wear out more quickly from charging cycles than ultra capacitors. Integrating theenergy storage technology not only could extend the range for electric vehicles, but also couldmean greater durability.Green Car Congress reports that an Argonne National Laboratory team led by Dr. DonHilebrand, director of the Center for Transportation Research, will assemble and evaluate anenergy storage system that combines ultra capacitors and lithium-ion batteries.Maxwell Technologies, Inc. will supply the ultra capacitor cells and integration kits to the U.S.Department of Energy. No word as to which company previously supplied the Argonne teamwith the advanced lithium batteries and power electronics. The design challenge is an integratedenergy system for hybrid-electric and plug-in hybrid vehicles. So, Maxwell has a lot to gainfrom collaboration with the Advanced Powertrain Research Facility (APRF) in Argonne Center forTransportation Research.A prime objective of the research project is HIL (Hardware-in-the-Loop) validation andbenchmark testing of this combined technology and their supporting subsystems for advancedvehicles. Plans are that the test system will undergo HIL validation during the summer of 2007.

Argonne and Maxwell have agreed on an active parallel system configuration thatwill combine a standard lithium-ion plug-in hybrid battery with a string of 112 ofthe Maxwell BOOSTCAP BCAP0650 P270 650-farad ultracapacitor cells, along withappropriate power electronics and cooling and safety-related features.

The other design challenge, frequently mentioned when ultra capacitors are used in tractionapplication (most recently in a Swiss context), is the cost of ultra capacitors. There has beenconjecture about the price coming down with mass production and new development, but, sofar, nothing to put on the asphalt.Nota Bene:When this blog applauds that finally there is testing underway of a combination of Maxwell ultracapacitors and advanced lithium batteries, it certainly could be subject to the criticism ofmissing prior art. A UK company, PML Flightlink, previously had installed and tested such acombination in a Mini Cooper S. The former testing was more “proof of concept”, whereas theupcoming testing should be more scientifically rigorous.Other Similar AG Posts Possibly RelatedAutomatically Generated

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Abstract (from “Power enhancement of an actively controlled battery/ultracapacitor hybrid”Lijun Gao Dougal, R.A. Shengyi Liu IEEE Transactions on Power Electronics, 20(1), Jan. 2005):

An actively controlled battery / ultracapacitor hybrid has broad applications in pulse-operated power systems. A converter is used to actively control the power flowfrom a battery, to couple the battery to an ultracapacitor for power enhancement,and to deliver the power to a load efficiently. The experimental and simulationresults show that the hybrid can achieve much greater specific power while reducingbattery current and its internal loss. A specific example of the hybrid built from twosize 18650 lithium-ion cells and two 100-F ultracapacitors achieved a peak power of132 W which is a three-times improvement in peak power compared to the passivehybrid power source (hybrid without a converter), and a seven times improvementas compared to the lithium-ion cells alone. The design presented here can be scaled

The EnerDel Lithium-Ion Battery

to larger or smaller power capacities for a variety of applications.

EnerDel/Argonne AdvancedHigh-Power Battery for HybridElectric VehiclesThe EnerDel/Argonne lithium-ion batteryis a highly reliable and extremely safedevice that is lighter in weight, morecompact, more powerful and longer-lasting than the nickel-metal hydride(Ni-MH) batteries in today's hybridelectric vehicles (HEVs).The battery is expected to meet the U.S.Advanced Battery Consortium's $500manufacturing price criterion for a25-kilowatt battery, which is almost asixth of the cost to make comparableNi-MH batteries intended for use inHEVs. It is also less expensive to makethan comparable Li-ion batteries. Thatcost reduction is expected to help make HEVs more competitive in the marketplaceand enable consumers to receive an immediate payback in gas-cost savings ratherthan having to wait seven years for the savings to surpass the premium placed onHEVs.Additionally, the EnerDel/Argonne battery does not use graphite as the anodematerial, which been the cause for concerns about the safety other Li-ion batterybrands. Instead, Argonne developed an innovative, more stable new form ofnano-phase lithium titanate (LTO) to replace the graphite. It also developed a newway of making nano-phased LTO that will allow for easier industrial processing, aswell as provide a high packing density that can increase the battery's energy densityand provide the power needed for vehicle acceleration and regenerative charging ofHEVs.The battery's principal developers are Khalil Amine, senior scientist and groupleader; materials scientist Illias Belharouak; Zonghai Chen, assistant chemist;Taison Tan, EnerDel's research and development manager; Hiroyuki Yumoto,EnerDel's director of research and development; and Naoki Ota, EnerDel presidentand chief operating officer.The DOE Office of Energy Efficiency and Renewable Energy's (EERE) FreedomCARand Vehicle Technologies program provides funding for Argonne battery research. email : ttrdc@anl.gov

An active parallel configuration controls the ultracapacitor energy flowsvia an energy management strategy with a power electronics converterto minimize battery cycling.

Green Car Congress reports that Maxwell Technologies, Inc. now has formed analliance with Tianjin Lishen Battery Joint-Stock Co., Ltd., Lishen, China. The leadingproducer of rechargeable lithium-ion batteries in China plans to manufacture andmarket novel hybrid energy storage system (HESS) products. The companies haveidentified a number of initial target applications for the combination of theirrespective ultracapacitor and li-ion battery technologies, ranging from quick-chargecordless tools to electric vehicles. Production and delivery of initial product samplesis anticipated in early 2008. After Green Car Congress reported that Maxwell Technologies, Inc. and TianjinLishen Battery Joint-Stock Co., Ltd. planned to manufacture and market novelhybrid energy storage system (HESS) products, combining ultra capacitors withlithium ion batteries, an interesting discussion ensued in the EV forum betweenDanny M, Morgan La Moore and “Kaido Kert”.La Moore began the discussion in a reply to Steven Ciciora about hybrid batterypacks. He suggests stiffening a flooded lead-acid pack, a.k.a., “floodies”, withA123’s cells, which don’t have the voltage drop problem that ultra-caps do.

The biggest design problem is matching the nominal and max voltagesof the A123 and flooded packs. (Also, the stiffening would only workreally well in the middle 80% of the A123’s SOC.)

During a subsequent exchange, La Moore makes the following suggestion:

To prevent the floodies from over-charging the A123’s, put a contactorbetween the floodies and the A123’s. When the A123 voltage dropsbelow 2.7 volts per cell, the contactor closes, and because the floodiesare about 10-20V higher than the A123’s, they start charging the A123’sat a rate determined by their internal resistance. When the A123voltage rises above 3.5 volts per cell, the contactor opens, and theA123’s handle all the load until they drop below 2.7V again.The circuit required isn’t very complicated, and the only expensivecomponent is the contactor. Depending on the internal resistance of thebatteries, it wouldn’t have to handle too much current, either.The more A123’s you use in parallel, the better they’ll handle thecurrent. I think you’d want at least enough to double the stiffness ofyour pack. (In the low quantities we’re talking about here, the A123’saren’t really all that stiff. You can control how stiff they are by changingthe amount you use.)If you have a 120V truck with 20 6V, 4 mOhm batteries, then thosebatteries have a combined internal resistance of 80 mOhms. A 34s4ppack of A123’s would have 85 mOhms internal resistance, so thecombination of both in parallel (when accelerating) would double thestiffness of your pack. (The voltage sag of the A123’s would trip thecontactor, which would put both in parallel, making it much more stiff.)The problem is that this would require 136 A123’s, which would cost$1190 plus shipping at E-bay prices. The A123’s would have a capacityof about 1 kWh. If I under-estimated the internal resistance of thefloodies, though, it wouldn’t take as much A123 to double the stiffnessof your pack.If you’re interested, I’m willing to draw up the circuit, post it here forothers to look at, and build it for you if the other EE’s on the list don’tnotice big problems with it.

Danny M. replied and the following is a subsequent exchange between La Moore andDMOn Nov 21, 2007 12:39 AM, wrote: “Unless there’s something different about A123’scharge procedures, I think you’re oversimplifying the charge procedure and it may

quickly damage the cells.”LM: I’m operating entirely in the middle of the range, where the procedure is“dump current in, don’t dump too much”. However, you’d have to be careful andchoose trip voltages such that you don’t fail the “don’t dump too much” part. Yes,charging a Li-Ion requires more care at the end of charge, but I cut off thecapacitor before then. A123’s are much, much less picky than most Li-Ion, and I’musing that to my advantage.DM: Shorting on the batt pack 10V-20V could create very high currents that couldbe bad for both batts. Aren’t A123’s rated for 30C at best?LM: Yeah, the A123’s are rated at 30C continuous, 52C peak. That equates to 70Amax continuous, 120A max peak.With a 120V floodie pack at a topped-off charge of 132V and ESR of 80 mOhm anda 34s4p A123 pack with a cutoff of 2.7*34=91.8V and ESR of 85 mOhm, you havea worst-case charging current of 243A. Split 4 ways, this is 60.8A, less than the 70Arating per cell of the A123’s. It’s probably not good for the cells to charge soquickly, though.If you change the lower cutoff to 3.0V, the max charging current is 182A (withtopped-off floodies); this is probably a better value. In that case, it would be agood idea to add temperature compensation so that you still operate in the middleof the range in low temperatures, though.DM: I doubt the A123’s going to pull it down to its normal charging voltage. Isuspect that like putting 300A charging current on a battery at 11V open-circuit(partial SOC) could bring it up to 14.6V instantly without regard to its charge state,this will make the A123’s terminal voltage rise above the set point even though itsSOC wouldn’t be up there yet.LM: No, that won’t trip the upper set point. Say you have a 34s pack of A123 and a120V “floodie” pack. The lower cutoff is 3*34=102V and the upper cutoff is3.5*34=119V. You just charged up and your “floodies” are sitting at 132V.You’re driving along, and your A123’s discharge below 102V. The contactor closes;now, ignoring the load, you get (132-102)V/(.165 Ohm)=182A charging the A123pack. The voltage between the internal resistances (what you’re measuring) is102+30*(85/165)=117V. This is a worst-case voltage, and any load from the motoror a “floodie” SOC below 100% will make that initial voltage even lower.DM: There’s also balance issues. Charging a long string of Li-ion is sort of a mess. Isuppose if you never try to reach full charge and use it as a buffer then the risk ofovercharging a cell is minimized at least.LM: Yeah, a BMS for the A123’s is definitely a good idea.The way I’d like to do it: use a proper buck converter in current-mode control, withthe output current equal to the moving average of the last 30 seconds of controllercurrent. This would require a microcontroller, current shunt, and DC-DC converter,though. The nice thing is that the DC-DC can be sized to the average load insteadof peak load, and it would have a voltage ratio of 3:4 at the worst and almost 1:1at the best, which is a good thing.A happy medium would be to do amp-hour counting on the A123’s and control thecontactor based on that.Then “Kaido Kert” adds:

If you substitute the contactor to a MOSFET/IGBT in this idea, and putsome cheap micro in charge of it providing the intelligence and PWM,this would work. Could probably work out cheaper than contactor andsave the batteries. But one would have to do the programming ofcourse.

Bill Dube’, developer of the KillaCycle, then comments on a related thread:

Just to add a little twist to all of this. A123 Systems are building, inprototype, cells with twice the specific power. (Half the internalresistance.)Also, by heating the cells to about 70 C, we manage to get 175 ampsper cell from the present M1 cells. This is an internal impedance of0.010 Ohms. David Schramm, Maxwell’s president and chief executive officer, whowould seem to be sticking to The Business Plan of Great Failure, saidthat the companies see a large market opportunity for their products.

We believe that the products we envision will give end-users

the best of both worlds in terms of the long cycle life, rapidcharge/discharge characteristics and low temperatureperformance of ultracapacitors and the large energy storagecapacity of lithium-ion batteries,” Schramm said. “We alsoplan to move some of our BOOSTCAP product assembly toLishen in order to leverage our joint process engineeringcapabilities, and Lishen will conduct development andqualification testing on battery electrode material producedthrough Maxwell’s proprietary dry process, so we see this asa deep and strategically important alliance for bothcompanies.

Energy Blog commentator bigTom observes:

This would seem to be a step forward for portable electricstorage systems. The ultracap can efficiently absord or putout significant short lived energy spikes, while the batteryallows significant long-term storage capacity.I would presume that the ratio of capacitor energy storageto battery energy storage would be fairly low, 1 to ten orpossibly 1 to 100. Quick charging the capacitor in order toleisurely charge the battery would not be effective in thiscase.Ultra-Caps are really amazing in their capabilities, but I’venever seen any information on cost.Presumably it is quite high per KJoule?

And, Energy Blog commentator Chan retorts:

Maxwell ultra caps will cost $0.02/Farad. That is $54 for a2600F Ucap @ 2.7V, which equates to $20/Wh.The USABC (United States Advanced Battery Consortium)wants $0.15/Wh (a factor of 100 less) in PHEV (Plug-inHybrid Electric Vehicle) battery, does it not?

Nesscap Super Capacitors with KokumLithium-ion Batteries

Subtitle: That’s Kokum, Not Hokum, Lutz BaitersAs previously noted, Maxwell Technologies and Argonne NationalLaboratory have been investigating combinations of batteries and ultracapacitors. Green Car Congress now reports that General Motors is“actively exploring” the concept, which is especially suited for the EREVs(Extended Range Electric Vehicles) “because of the combinedrequirement for high energy and high power.”General Motors had indicated previously that their concept vehicle, theVolt, would an EREV. During a recent presentation at an AABC(Advanced Automotive Battery Conference) in Tampa, Florida, Dr. MarkVerbrugge, Director, Material and Process Labs at GM’s Tech Center, saidthat GM is testing a proof of concept system consisting of 6 100FNesscap supercapacitors and two Kokum high-energy lithium-ionbatteries.

Initial results from General Motors tests show improved power deliveryfrom a combination of 6 100F Nesscap super capacitors and two Kokumhigh-energy lithium-ion batteries compared to two conventional Li-ionbattery systems (Supercap-Li-ion combo is the green line). (Note:Although contraindicated, no DC/DC converter was used in order to keepcomplexity down.) The tests were conducted at lower battery surfacetemperatures and testers noted a slight sacrifice in energy density.AG readers may recall that researchers at the Electric Vehicle Instituteat Bowling Green State University developed and patented asupplemental, electric drive that uses ultra capacitors to complement anexisting propulsion system. Nesscap super capacitors were in the proofof concept transit bus developed for NASA. More recently, implementedthere have begun pilot projects with Maxwell ultra capacitors helping topower transit buses. However, this has been with super capacitors alonerather than a combination. Super capacitors alone have also beenproved on the race car track.On the other hand, AG readers may recall that PML Flightlink has testeda combined system in a passenger car. And, more recently, AFS TrinityPower Systems of Bellvue, Washington, has tested a converted SaturnVue. Not only was the AFS test vehicle a flex-fuel, plug-in, the energystorage system was a combination of ultra capacitors and standard,deep-cycle batteries.Other Similar AG Posts Possibly RelatedAutomatically Generated

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Writing for the Canadian Financial Post, Nicolas Van Praet reports on arecent assertion by Masaaki Kato, who is president of Honda Motor Co.’sresearch unit, that Lithium-ion powered cars would fail to satisfy mostconsumers, because they are costly and such batteries still hold lessthan half the energy of gasoline by weight.Those reasons — high cost and less energy — are correct for now. Thesnapshot of consumer behavior taken by Kato is more accurate thaninaccurate since it certainly will require a significant shift by consumersto adapt to electric drive. Honda Motor Company, which is world renownfor building exceptionally quality automobiles, has done considerableresearch on electric drive vehicles, so this is other than someone’suninformed opinion.On the other hand, it seemingly ignores how electric drive addresses thecombined threats of Peak Oil and Climate Devastation. (Editor’s jibe:

Kato is no doubt a member of the Society of Automotive Engineers(Otto motive means propulsion from internal combustion operating onan Otto cycle) and probably a honorary member of the Most EsteemedMakers of Buggy Whips.) It also ignores the leap frog effort by Chinesecar makers, which is expected because of lower cost to take a biggerbite of future market share than the “Shebby Bolt“.And, while HMC is to introduce a dedicated gasoline-electric hybrid carnext year to compete with Toyota’s Prius, Kato’s snapshot would seemto ignore the obvious success of the Toyota Prius, which offers anelectric only at low speed mode. It also sidetracks from the decidedadvantage of kinetic energy reclamation. Lastly, the Kato observationwould seem oblivious to the global gearing up by battery manufacturers.He certainly is correct that battery technology needs to advance further.Nonetheless, his decision that battery-powered vehicles have yet tobecome widespread and popular in the market to warrant manufacturingby Honda does seem ill-advised. (Editor’s exhoration: AG readersdemand a plug (No plug, No deal!), you have nothing to lose but yourGHG! Also, tell the plug-in hybrid makers that you want a mediumspeed electric only mode while they are at it.)The author interviewed Jerry Chenkin, executive vice-president ofHonda Canada Inc., who opined, “The key is in the end we need toconserve the world’s energy resources and protect the environment forfuture generations.” Toward such a goal, Honda “is pushingzero-emission hydrogen fuel cell technology. This summer, it leased anew hydrogen-powered sedan called the FCX Clarity to a limited numberof U.S. clients for $600 a month.” Mike Millikin relays a report that “China, already a global center forlithium-ion battery component production and battery manufacturing, isramping up its research and development efforts in the field, bothwithin the private sector and with government support.”

At the 1st International Conference on Advanced LithiumBatteries for Automobile Applications, organized by ArgonneNational Laboratory, Dr. Jiqiang Wang of the TianjinInstitute of Power Sources (TIPS) provided an overview ofthe government-supported R&D projects for lithium-ionbatteries for transportation, which are now focusing on twoprimary cathode materials: manganese spinel (LiMn2O4) andiron phosphate (LiFePO4).Dr. Wang began by observing that the Beijing Olympics hadserved as a large-scale field test for some of thedomestically-developed lithium-ion technology: there were55 electric passenger buses and 20 fuel cell hybrid vehiclesequipped with lithium-ion batteries that accumulated about200,000 km (124,000 miles) of service during the Games.Fifty of the buses used lithium-ion systems with 137 kWhcapacity, comprising 7 smaller packs of 10 kWh each andthree larger packs with about 20 kWh each. These packsused 90 Ah prismatic cells from Beijing Citic Guoan Mengguli(MGL), with LiMn2O4 cathodes. The other five buses used 10large packs with a total of 205 kWh capacity.The fuel cell hybrid vehicles used 350V packs comprising8Ah prismatic high-power cells from Suzhou Phylion BatteryCo., Ltd., again with LiMn2O4 cathodes. The packs deliveredmaximum pulse power of 50 kW.According to an overview of lithium-ion developments inChina published by Argonne earlier this year, MGL ranks asChina’s largest manufacturer of LiCoO2 cathode material,and is the first to market the new materials LiMn2O4 andLiCoO0.2Ni0.8O2. Besides cathode materials, MGL alsoproduces lithium-ion secondary batteries of high energydensity and high capacity for power and energy storage.Suzhou Phylion Battery Co., Ltd., is a battery technologycorporation set up by Legend Capital Co., Ltd.; the Instituteof Physics of the Chinese Academy of Sciences; and

Chengdu Diao Group. The company specializes inmanufacturing and selling lithium-ion cells with highcapacity and current, and has been selling into the portabledevices, battery-powered tools and e-bike markets.The batteries deployed in the vehicles for the Olympicsadhered to a new, more stringent national safety standard.The performance of cells and modules needed to beconfirmed in one of two national testing centers, in Beijingand Tianjin.Looking ahead for the next two or three years, said Dr.Wang, the government-supported 863 project will continueto support R&D on LiMn2O4, but will also start to supportR&D on LiFePO4.

The government has set development targets for iron phosphate andmanganese spinel cathodes for HEV and EV applications:

Specifications for Li-ion batteries

Capacity (Ah) 8, 20 50 100

Specific power (W/kg) ≥1,800 ≥700 ≥500

Specific Energy (Wh/kg) LiFePO4 ≥65 ≥110 ≥110

Specific energy (Wh/kg) LiMn2O4 ≥70 ≥120 ≥120

Max. discharge rate 30C (20s) 6C (30s) 5C (30s)

Max. charge rate 10C (10s) 4C (60s) 4C (60s)

Cell internal resistance (m&Ohm;) ≤2.0 ≤3.0 ≤2.5

Cell-to-cell voltage deviation (V) ≤0.02

Cell-to-cell capacity deviation (%) ≤2

Operating temp. range (°C) -25 to +60

Storage temp. range (°C) -40 to +80

Charge retention (28 days at ambient

temp.) (%)≥90

SOC estimation error (%) ≤5

Safety Pass industry or specified standard.

Whole battery running life (104km 15 (LiFePO4); 10 (LiMn2O4)

ReliabilityOperate normally under environment humidity of 100%; meet relative

requirements during whole vehicle running mode test of 30,000 km

Cell-level cost at mass prod.

(Yuan/Wh; US$/Wh)≤3/ ≤0.44 ≤2/ ≤0.29 ≤2/ ≤0.29

Lishen and BAK are each leading an R&D group for lithiumiron phosphate development for EV and HEV applications;MGL and Phylion are each leading an R&D group formanganese spinel development for EV and HEV applications.Research is also looking into new anode materials, such ashard carbon.Besides the government-sponsored research programs, Dr.Wang noted, there are several large lithium-ion batterymanufacturers who are also doing R&D on lithium-ionbatteries for EV and HEV applications, such as BYD. The Edgerton Center Summer Engineering Workshop — agroup of students from MIT and their friends from somearea high schools — have started an electric kart project.

“The [electric] kart is capable of going about 35 miles perhour and has a max output of 300 amps.”

Weighing in at 350 lbs. with 36 volts oflead-acid batteries on board, the coolest piece ofthe e-kart puzzle is the ultracapacitor “boost”mode. That capacitor is also called upon to storeextra energy from braking that would otherwisebe lost.The students designed and built their own motorcontroller in lieu of purchasing one off-the-shelf.A separately excited motor allows for a bit of“gearing” despite the single speed transmission.

Battery / Capacitor CombinedEnergy Storage

At the recent British Motor Show, PML Flightlinkand its partner Synergy Innovations showed aMINI QED — an in-wheel, plug-in, series hybridconversion of a MINI, which many would agree isa fun car to drive even before these developersachieved an ability to accelerate from 0-60 in4.5 seconds.Speaking of incorporating ultra caps into theelectric drive, I recently learned from MikeMillikin that PML Flightlink put 350V worth of 11Farad ultra capacitors into its Mini QEDprototype. The ultra capacitors accept power

from regen braking and discharge when highcurrent is required for acceleration.

For now a combination of ultra capacitors andadvanced lithium batteries is possible only in a“proof-of-concept” prototype. As one GCCcommentator observed, “I’d hate to see thebill.”My ignorance of power electronics still preventsme from puzzling out how exactly the bank ofultra capacitors and the lithium battery packinteract. The GCC article focused more on theengineering of anti-skid and traction controlafforded by in-wheel motors than on combiningpower from ultra capacitors and advancedlithium batteries.In the commentary, there was considerablediscussion regarding pros and cons of in-wheelmotors, plus evidence that such performance isonly possible with a high power / high energysystem.Other Similar AG Posts Possibly RelatedAutomatically Generated

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