• Mar 3rd 2011 at 5:04PM
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2012 Buick Regal eAssist – Click above for high-res image gallery

When General Motors debuted the 2012 Buick LaCrosse with eAssist at the Los Angeles Auto Show in 2010, the automaker made it clear that this fuel-saving technology would find a home in other models soon. Last month, the eAssist-equipped 2012 Buick Regal made its debut at the 2011 Chicago Auto Show.

In the future, The General will wheel out more eAssist-equipped vehicles, as the system is GM's default mild hybrid setup for electrification applications requiring 20 kW of power or less. Currently, eAssist utilizes a 115 volt, 0.5 kWh lithium-ion battery, an electric motor and regenerative braking to boost fuel economy, but Maxwell Technologies chief executive officer David Schramm says that ultracaps and eAssist "are a perfect fit." Here's his reasons why:
  • Charge/discharge rate: Anyone who uses a mobile phone or other device powered by a lithium battery knows that it can take up to several hours to recharge the battery, so how much energy can such a battery absorb during the few seconds that it takes to stop a car? By contrast, ultracaps fully charge or discharge in a second or less.
  • Cold temperature performance: When temperatures approach freezing, batteries become sluggish, so they won't be able to deliver much power to the battery or capture much regenerative braking energy in cold climates. Ultracaps operate normally down to -40ºC.
  • Operational lifetime: Batteries typically last only a few thousand charge/discharge cycles before they need to be replaced, whereas ultracapacitors can be expected to last the life of the vehicle.
Schramm closed by almost daring GM to give ultracaps a shot, stating:
We're convinced that Maxwell ultracaps would also make the eAssist system more efficient and reliable, thus enabling GM to deliver a superior product to its customers, so we hope they will take us up on our offer to prove it.
Would ultracaps boost GM's eAssist to the next level? Let us know what you think by dropping a comment below.

2012 Buick Regal eAssist
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    • 1 Second Ago
      • 4 Years Ago
      there is a small parameter window where current tech super caps can be a rational choice, weight benefit wise. because they can handle strong current many times you can have regen braking strong enough to almost completely do without mechanical brakes, even emergency braking from motorway speeds.
      but it comes at a cost. not only the capacitor costs which maxwell charge a comfortable price for (comfortable for them, not the buyer) but you need a motor and drivetrain strong enough to handle it, a strength equivalent to a 0-100km/h acceleration in 3seconds (emergency braking). you also need a matching strength 2-way power electronics channel to the capacitors because their profile is not the same as batteries so can't use the same power electronics.
      so it wouldn't be an easy way, more like the royal treatment to handle those rare high power brakings without the use of mechanical brakes.

      in short, I don't think you will see them soon in 'family cars'.

      for a race car though it can make some sense although at racing energy levels (speeds) the density of maxwell supercaps is only on the edge of what you'd want. meaning their weight to capture the energy from a high speed slow down will affect the car's performance (200km/h holds 4x the energy of 100km/h). with current tech they would probably not choose a cap bank large enough to capture a 200km/h braking which would be maybe 100kg for the caps alone. that mass could be batteries instead..

      you might see a moderate super cap bank in some rare models but given how incompetent the car makers are now and how they mess up even simple decisions, I wouldn't hold my breath on something that's a complex EV solution like this would be.
      • 4 Years Ago
      Wow, this guy is either totally ignorant about hybrid batteries, or he's trying to sell us something...

      Maybe these capacitors can do the same job better, but just try to find a Prius owner who's ever had to replace a battery because it's come to the end of its lifetime before the car has. There's only a couple million hybrids out there, and production examples have been around for what? 15 years now?

      At least two out of three of his claims are truthful, anyway.
        • 4 Years Ago
        Capacitors are so good at preventing excessive depth of discharge in the battery that they can be used in conjunction with lead acid batteries, and don't really need NiMH.
        See my above extensive post in reply to skierpage for costs.
        The cost against NiMH is reasonable as you don't need to replace the NiMH for all of it's rated capacity, you only need around 100wh due to capacitors very high power density.
        None of this is new technology. They are already extensively used in wind turbines and electric buses, and now in cars from Peugeot/Citroen.
        • 4 Years Ago
        Yeah, it is lead acid in the Peugeot system:
        'The car has a conventional internal combustion engine and a lead-acid battery for initial starting and to power other electrical loads, such as air conditioning, lighting, entertainment systems, etc. New components required to support the stop-start idle elimination function include a belt starter alternator for repetitive starting, an ultracapacitor booster module to provide power for repetitive starts, and power electronics to manage “brake/throttle logic” that turns off the engine as the car slows and “strategy start” electronics to signal the system to seamlessly restart the car when the drive touches the accelerator or clutch pedal.

        For a few hundred Euros more than its standard models, PSA offers cars that consume up to 15% less fuel in city driving and reduce CO2 and other emissions by an equivalent amount. PSA also notes that incorporating ultracapacitors for starting allow it to reduce the size of the battery by 30%, making it small enough to be located under hood instead of in the trunk. That eliminates 20 feet of heavy, expensive, copper battery cable and reduces wiring complexity and assembly labor, partially offsetting the cost of the stop-start system components.'

        • 4 Years Ago
        David, all you really need was the data from the last paper. With very shallow cycling, ~the cap/LA battery combination will last longer than a conventional battery, but it will still have a poor lifespan compared to a NiMH battery.

        Look at the testing conditions in the pdf. For the simple cycle life tests where the ultrabatt lasted about 2x longer than a conventional battery, 17000 cycles versus 8000 cycles, the test consisted of discharging the battery for 30s and 2.5 times the five hour rate. At the five hour rate discharging a battery for 30s is roughly discharging it .2%. 2.5 times that is what .5%? From the Ovonics pdf I linked before, cycle life at 15% depth of discharge for NiMH cells is in the 100,000+ range, at .5% it approaches 1,000,000 cycles.

        The point I'm making is that while it's nice that caps can increase the life of LA batteries, which is probably good for starting apps, they still won't approach the lifespan or energy to weight ratio of NiMH batteries.
        • 4 Years Ago
        BTW, the Prius battery uses some sophisticated engineering to keep it working in the cold.
        Capacitors just work without getting fancy.
        • 4 Years Ago
        David, NiMH battery lifespan strongly depends on depth of discharge.


        While a 1kWh NiMH pack may only store ~1000kWh (1kWh at 1000 cycles) over it's lifespan if it cycles at 100% dod, at 50% dod it can store well over 5000kWh (.5kWh at 10000 cycles), so for most cars battery pack lifespan is not an issue. Even for vehicles like taxi cabs lifespan is usually in the neighborhood of 300k+ miles.


        If Maxwell could get the price of their ultracaps down to ~2x the cost of NiMH cells they might have some market share, but that isn't the case right now AFAIK.
        • 4 Years Ago
        Ernie, have another read of what is going on. The Prius battery is a totally different case, as for a start it is a NiMH battery not a lithium one, and so you can't just assume that lithium batteries in all chemistries will give you as good a life, and secondly it is around 1.4kwh, IOW huge compared to the small batteries used purely for stop/start instead of hybrid use. AFAIK the Prius, at least in the early designs, also does not pause the engine in the same way as a modern stop/start does, so that you will have literally hundreds of thousands of events.
        Lastly if you are going for regenerative braking a capacitor will do a far better job than any battery, due to it's fast charge capabilities.
        The 100watts of so can then be gradually transferred to the battery at a pace it can accept, or used direct from the capacitor.
        That is why capacitors are also used on wind turbines to compensate for microsecond gusting in addition to batteries, and why they are used in buses.
        • 4 Years Ago
        David, manufacturers will still need NiMH batteries unless people are OK w/ replacing the heavier battery pack every 60k miles. Caps can significantly increase the power density of LA batteries, but the energy density and cycle life will still remain about the same.

        You can try to replace ~.75kWh-1kWh of usable NiMH battery capacity with .1kWh of super-caps, but engine operation would have to be completely revamped, and being cycled on/off ~5-10 times more often isn't very good for emissions or wear.
        • 4 Years Ago
        Using capacitors to buffer the battery and prevent excessive depth of discharge does indeed significantly increase cycle life:
        'Testing results show that no matter what kind of hybridization the system is, power is enhanced with a factor β, and due to the power enhancement, current demand to the battery system is lowered, which extend the batteries’ cycle life.'


        'The relation between the cycle life and the depth of discharge is logarithmic as shown in the graph below. In other words, the number of cycles yielded by a battery goes up exponentially the shallower the DOD. This holds for most cell chemistries.'


        And finally, from a 2006 report, so the state of the art and costs for battery/capacitor combos have moved way on from that given here, but it illustrates cycle life considerations:
        'The cycle lives of the
        lead-acid batteries were less than 8,000 cycles, while
        the UltraBattery achieved up to 17,000 cycles,
        approximately twice that of the lead-acid batteries.'


        That's not so say that capacitors can't be combined with lithium or NiMH batteries, but that it may not be necessary in a given application due to the enhanced cycle life of lead acid.

        The other concerns you mention such as engine life are common to all stop/start configurations whether they use capacitors or not, and are also essentially solved problems as stop/start is common in European vehicles, employing clever strategies such as careful positioning of the cylinders when the engine stops and so on.
        • 4 Years Ago
        Hi roflwaffle.
        You sought to argue that:
        'the energy density and cycle life will still remain about the same.'

        which is not the same as:
        'The point I'm making is that while it's nice that caps can increase the life of LA batteries, which is probably good for starting apps, they still won't approach the lifespan or energy to weight ratio of NiMH batteries.'

        Batteries need to be matched to applications, and it is perfectly true that NiMH will last longer than lead acid and certainly will weigh less for a given energy density.
        Just the same if you can avoid the deep discharge which really shortens cycle life for lead acid the trade offs may be worth it, as after all car manufacturers aren't looking for the batteries to have infinite life, but acceptable life
        Lead acid battery technology is not totally static either, which is why I merely presented that old paper as indicative, rather than for reference to the precise figures.
        A whole host of different engineering solutions will be reached. Personally I would prefer lithium batteries, as their price drops due to their low weight and with some chemistries high cycle life, but lead acid may also be used sometimes and AFAIK that is what is used in the Peugeot, and the battery life is improved although not perfect.
        • 4 Years Ago
        Prius and other hybrid batteries don't get worked as hard as EV batteries, so I don't think there's much difference either way.
      • 4 Years Ago
      Great! How about Maxwell buy an eAssist hybrid and replace the battery with ultracaps, and let us know how it goes?
        • 4 Years Ago
        The favstocks quote is just a random one from a whole bunch which came up on Google when I put in Peugeot and Maxwell in a search, the point being that the technology which is fully described in the 2007 GreenCarCongress link has now been fully developed and is in production cars.
        That means that although there would be some testing in the context of the GM system and their requirements, the basic job is already done and the battery/capacitor combination works just fine - it is not much more complicated now that Maxwell and Valeo have their system working than adapting any other standard part.
        The point of a capacitor is that it is not very energy dense, but it is far more power dense than any battery.
        That means that you don't need to put in 0.5kwh of capacitors, but instead mate around 100wh of capacitors with some batteries, and since the capacitors save the battery for high depth of discharge which is what kills them, especially lead batteries, you can use the far cheaper lead batteries for balance of system.
        The battery takes care of most of the energy storage needs, and feeds the battery which provides the surge of power needed for stop/start, and which can take the surge of power from heavy braking.
        Running the numbers that only takes around 100wh or so of capacity.
        A lot of the battery capacity in this application is simply there to provide enough power for the surge, so the energy density has to be over specified.
        100wh of capacitor at 20wh/kg gives you around 5kgs of capacitor, plus some battery, although less than you would otherwise need.
        Costs of capacitors are in the right range. The Valeo system as used in the Peugeots reckons it saves around 80% of the cost of conventional micro-hybrids, partly by using it to feed ancillaries rather than feeding into the drive train.
        Do read the link - it is all laid out there!
        • 4 Years Ago
        The ultracaps needed for a micro hybrid might be as little as 30wh
        'The micro-hybrid used a 30 Wh, 6 kW peak power ultracapacitor unit. Burke ran additional computer simulations for higher motor power (up to 12 kW) and larger ultracapacitor energy storage (up to 50 Wh) in the micro-hybrid application, and found that the improvements in fuel economy were only marginally greater. Using a motor power of 3 kW reduced the fuel economy improvement on the FUDS by more than 50%.'


        And working to include them in the GM system:
        • 4 Years Ago
        @David: those fleet busses and industrial turbines are at different price points from a consumer mass-production product. I don't think they're relevant at all to a mass-production passenger car.
        • 4 Years Ago
        @David: FWIW, I am an engineer, and I have built actual, working electrical devices that incorporate capacitors to smooth power flow.

        Quite frankly, the whole thing is the other way around: Maxwell CEO thinks that GM's eAssist hybrids would be ideal for Maxwell's ultracaps. He sees massive guaranteed potential volume over the next decade, and would dearly love to displace whomever GM currently uses. I don't blame him for this, but think the onus is on him to show how his product works in a Buick.

        If it really is the best application, then the cost of a proper, functional proof-of-concept vehicle is a trivial downpayment on the future of his company.
        • 4 Years Ago
        Maxwell capacitors in car use:

        And where you can buy them:

        This is not vaporware, but standard, off the shelf, cost effective technology.
        • 4 Years Ago
        "Great! How about Maxwell buy an eAssist hybrid and replace the battery with ultracaps, and let us know how it goes?"

        Lol... all joking aside GM really should consider every option available to them, especially with a company that is more than willing to work with GM to make it happen. With the increased reliability and other benefits its a potential win / win situation. Why not?
        • 4 Years Ago
        Indeed, Maxwell doesn't have to lecture anyone, just deliver a working prototype as Tesla did for the Smart ED and RAV4.

        Ultracaps' high power density can restart an engine, but unless you put a lot of them in the car they can't help propel the car down the road for a significant distance or time as eAssist can. I think 0.5 kWh of ultracaps would weigh over a hundred pounds, the same or more than the eAssist lithium-ion battery. It sounds like Maxwell's Boostcap in Peugeot HDi delivers 2.2 kW for 400 ms, which is a negligible 0.00025 kWh.

        The trend in hybrids is to increase the battery size to gain MPG from more time spent in more efficient electric operation, and to eventually plug in. AIUI, a larger battery can discharge/recharge at higher power, so that advantage of ultracaps diminishes. Likewise, the recharge/discharge in each stop-start cycle is a smaller percentage of SOC for a larger battery, so it's less damaging.

        @David Martin, careful, favstocks.com just regurgitates a GreenCarCongress post verbatim but breaks its "Earlier post" links.
        • 4 Years Ago
        I am afraid I do not follow you at all. The Maxwell capacitors are being used in mass production for Peugeot/Citroen cars:

        This is early days, but they are very much in mass auto production.
        What else do you want?
        • 4 Years Ago
        @David: Actually, Maxwell needs to show how their ultracaps work in a mass-production vehicle at a mass-production price point, so converting a Buick LaCrosse or Regal as a working proof-of-concept vehicle that works in the real world, is far more effective than merely saying they're "convinced".
        • 4 Years Ago
        GM are just using lithium batteries without any assistance from ultracapacitors, so Maxwell is not exactly trying to replace a direct competitor, but introduce a different technology.
        • 4 Years Ago
        BTW, if you suppose that the use of capacitors to cover short term fluctuations in power is new, there are around 2,400 hybrid buses currently using Maxwell capacitors and 1,400 wind turbines as well as AG Continental and Valeo's efforts in cars.
        • 4 Years Ago
        They don't need to. Maxwell capacitors are already used in Peugeots in a Valeo system, and they work fine:

        Technical details here:
        'The powerpacks must last for the lifetime of the vehicle, deliver reliability in the harsh thermal environment created by being close to the engine, and be safe and environmentally friendly. Valeo is specifying 600,000 stop-starts, 1 million regeneration events, and 200,000 boost events for the system.

        The first generation StARS with start-stop capability, which did not include a dedicated energy storage component, initially was offered in 2004. The new 14+X architecture incorporates enhanced electronics and an ultracapacitor energy storage module that allows it to recuperate and store energy from braking, which otherwise would be dissipated as friction and heat in a conventional braking system.'


        A lead acid battery works fine with ultracapacitors, you don't actually need to go to the expense of a lithium battery.
      • 4 Years Ago
      @David Martin,
      Try to spend less time writing long-winded verbiage and listen more carefully to what others are saying. Nobody disagrees ultracaps can work for stop-start micro hybrids; I think micro hybrid is useful tech and I wish it was on all cars. But eAssist is a fairly powerful mild hybrid. The mpg increase it delivers is substantial because it has a 0.5 kWh 15 kW li-on battery powering a substantial 11 kW motor. Replacing that with a different system (ultracaps and a less powerful lead acid battery) would deliver less mpg.
      • 4 Years Ago
      The LaCrosse has dropped its base model with the appearance of the Regal. It has made E-Assist standard on all LaCrosses.

      E-Assist should be standard in the Regal with the possible exception of the base fleet rental model.
      Like the laCross this base model can be dropped when the Verano appears.

      Then E-Assist can be a standard option on upscale Veranos with the possible exception of the entry fleet rental model.

      Only by establishing a Brand identity, can the Buick brand profit from such a relatively simple change. To complete the change, they could offer a Two mode hybrid on the Buick Enclave SUV, like the "Rendez-Vue" and the Buick brand would have a true identity and different from the more the performance oriented Cadillac brand. It would offer Fuel Economy, luxury and an alternative definiton of modern technology, across the entire Buick brand.
        • 4 Years Ago
        Good post. I wrote something very similar on AB a while ago, when Buick announced eAssist would be standard on the LaCrosse.

        As you note, eAssist technology should become part of the Buick brand identity. It's giving Buick the space, comfort, and perceived safety of a larger vehicle combined with the fuel economy of a much smaller vehicle. This means Buick doesn't have to offer a subcompact car, because all Buicks will have inherently good mileage within class.

        BTW, similar with Turbo technology for "performance" - turbo gives good power when you need it, with minimal loss off boost. Good match for the brand.

        And, of course, the eAssist push pretty much guarantees Buick will add this to the Enclave for best-in-class mileage, along with getting a sedan based on the 2nd gen Volt when that finally comes out - personally, I'd have the Buick headline for the 2nd gen Volt, but that's just me.

        Combined, this indeed sets Buick apart from GMC and world-class performance-oriented Caddy, with a clear fuel economy and luxury approach. It also helps justify the price premium over value-oriented Chevy or GMC.
      • 4 Years Ago
      I think that ultra caps are a great idea for this, however "a perfect fit" would include a competitive price. He must of forgot to mention that.
      • 4 Years Ago
      David, NiMH battery lifespan strongly depends on depth of discharge.


      While a 1kWh NiMH pack may only store ~1000kWh (1kWh at 1000 cycles) over it's lifespan if it cycles at 100% dod, at 50% dod it can store well over 5000kWh (.5kWh at 10000 cycles), so for most cars battery pack lifespan is not an issue. Even for vehicles like taxi cabs lifespan is usually in the neighborhood of 300k+ miles.


      If Maxwell could get the price of their ultracaps down to ~2x the cost of NiMH cells they might have some market share, but that isn't the case right now AFAIK.
      • 4 Years Ago
      the beauty of ultra-caps is not their ability to power the car for long periods of time ... or really even for short periods of time ...

      their strength is their ability to capture the regeneration "juice" easily and even more important allow for a high rate of discharge when starting up from a stop or during hard accelleration ... 2 things that conventional batteries do not do well ... in fact its the hard starting and acceleration that causes conventional batteries to drain too fast ... and heat up ... it is tying ultra-caps in with conventional batteries that the advantage is the greatest ...
      • 4 Years Ago
      Regarding low temperatures, that's becoming less of an issue with some chemistries:

      • 4 Years Ago
      Forget Maxwell, EEstor will will have everyone beat. Why? Because they've never failed on a promise. If Maxwell is successful, then that will tell me that EEstor either owns or has string-puppet control over Maxwell.


      EEstored 4 life
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