Electric Cars

Published on August 8th, 2014 | by Christopher DeMorro


EV-Lite Project Reduces Battery Weight By 41%

August 8th, 2014 by  


Electric cars are quickly overcoming the hurdles of cost and range anxiety, but one area that still needs improvement is the added weight of big battery packs. UK-based Cenex has just completed a two-year project to reduce both the weight and cost of EV batteries, succeeding by shaving 99 pounds, or about 41% of the weight off a standard EV battery, reports Green Car Congress.

Cenex also achieved a 63% reduction in the cost of non-cell battery components, and ultimately the company hopes to enable mass production of lower weight and cost battery packs. Cenex made these weight and cost savings by eliminating the need for wires and screws in the battery pack, massively reducing the number of battery components; in two similarly-sized 4 kWh battery modules, the EV-Lite project used just 196 separate components, compared to over 800 in a conventional battery pack.

Cenex also developed an innovative safety feature which isolates individual cells in case of a fire, and the team derived five different patents for their efforts. Considering that the average EV battery is complicated, costly, and in the case of the Tesla Model S, can weigh upwards of 1,300 pounds. Reduce that by 40%, and you just shaved over 500 pounds from the curb weight of the Model S, which would mean more range and better driving characteristics.

Lighter batteries have a lot of benefits, and once automakers overcome the bugaboo of weight, we should start seeing some really long range EVs.

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About the Author

A writer and gearhead who loves all things automotive, from hybrids to HEMIs, can be found wrenching or writing- or else, he's running, because he's one of those crazy people who gets enjoyment from running insane distances.

  • spec9

    NICE. This is the type of innovation and optimization that does not occur until you have a mass market for EV components which we are now starting to get. The more they can reduce the weight and cost of batteries, the more economically practical EVs become.

  • sault

    So they shave 41% off of the “non-cell” components’ mass. Then, you don’t need as many batteries to go the same distance, lowering vehicle mass even more. Then, you can use lighter components since the vehicle has less mass, lowering weight even more. While these are 2nd or 3rd order feedbacks, you can achieve a lot of system-wide mass reductions in this way.

    • jeffhre

      That is true, though since Tesla, Nissan, BMW, GM, Mitsubishi, Daimler, Volkswagen, Porsche and Kia do not use “standard battery packs,” what will this ultimately mean? I certainly hope the OEM’s can add this to their knowledge base for effect, but…

      • sault

        It might diminish some of the mass reductions, but many of these techniques can be adopted for a wide range of battery packs. Either that, or when Tesla, Nissan, etc. designs the next iteration of their packs, the might be able to incorporate some of these design improvements or they may foster even greater innovation during this process.

        • jeffhre

          Yes, if they have not pursued many of the same techniques, and hadn’t reached the same conclusions independently.

  • Saving 41% in weight over “standard battery packs” does not mean this can shave 500 lbs off a Model S.

  • Vensonata

    The more I read over the article the less I believe it. “Shave 500 lbs off the curb weight of the model S”? Yah, those Tesla slackers, don’t they care? (Sarcasm).
    I think there must be some substance to something to do with battery packs in this report, but it is very opaque.

  • JamesWimberley

    Hold your horses. Cenex’ claim is not 41% off the weight of the battery; it’s 41% off the weight of the non-cell components. It’s 45 kg off their reference battery pack, say 5-10%. So incremental rather than revolutionary progress, as you’d expect.

    On the other hand, the pedigree of Cenex’ partners is good: major manufacturers, a British government research agency, and a decent technological university. It’s a non-profit consultancy, so has little incentive to hype. It looks very credible to me.

    • Douglas Card

      achieved a 63% reduction in the cost of non-cell battery components”

    • Douglas Card

      no mention of weight of non cell components, just 41% reduction in battery weight.

      • JamesWimberley

        The complete sentence from Green Car Congress is: “The project realized a 41% reduction in weight and a 63% reduction in cost of the non-cell components.” There is no comma, so the “non-cell components” governs both reductions. Any remaining ambiguity is removed by the absolute figure of a 45 kg reduction. Battery packs weigh more than ten times that.

    • No way

      I just feel like the article is missing a lot of information and specifications to be able to see if it’s an improvement that will have any real world effect. Maybe you or someone else has more information to share regarding this weight reduction.

      • jeffhre

        Good luck, I don’t think any OEM’s are in a hurry to announce cutting edge proprietary information relating to it. But I have heard that Tesla is willing to let you look at their patents!

        • No way

          The information I wanted is not something they would need to keep secret. I basically just wanted to know what battery they have been shaving the weight off. I would have been happy with something like “We took a Leaf battery pack it weighs this much in the car today. It is 6 modules of 4 kWh each. Each module weighs xx kg and when we were finished with the module its weight was xx kg. And in the end the total battery pack had the weight of xx kg when we put it back into the car.

  • No way

    What is a “standard EV battery”? As far as I know and have seen all the car makers have their own design and components in their battery packs, making them anything but standard.

    Is there any manufacturer using this “standard” battery today in their car(s)? Is it even close to the market leader, Tesla, in weight after the reduction?

    So the original battery pack weight was about 240 lbs (if 41% is 99 lbs). What was the battery capacity? If it was 12 kWh (a leaf battery pack is 24 kWh and weighs 480 lbs) then the it would mean about 186 Wh/kg. That could be compared to the Tesla pack that is supposed to be around 150 Wh/kg (for the whole pack, not the batteries).

    In that case it would be an improvement. But mostly for other car makers since the new Tesla pack probably coming this winter with the Model X is rumoured to be a bit better than that.

    Anyway, every improvement for any manufacturer will benefit the market. So it’s great news if applicable in the real world.

    • RandomReader

      The article seems to imply that they were 4KWh modules … which [ after factoring your calculations ], makes the savings no where near impressive.

      • sault

        Well, since battery packs are made up of a bunch of modules stacked together, if you improve things at the module level, then you just rinse and repeat for larger and large packs and the benefits scale somewhat as well. Plus, it sounds like they reduced the weight or eliminated entirely a lot of connectors, bolts, etc. for the whole battery pack and these benefits can translate to larger batteries regardless of their size.

        • No way

          Sure… but if you’re starting from extremely poor levels compared to the competition (Tesla) then big improvements might be pretty useless if they are not competable anyway.
          Then you might think about a re-design all together instead.
          And maybe “cheat” by starting out like Tesla have done and then see if you can improve upon that.

      • No way

        I thought they were 4 kWh modules when reading the article too. But I deemed that impossible since then it would have been 3 times as heavy as the battery packs in electric cars today which already are considered way way to heavy compared to what they could and should be if designed better.

    • spec9

      Good question. They probably picked a sub module size that is around the size of the submodules in the Leaf and Volt. They both use rectangular cells that are like the one in the picture.

  • Vensonata

    Wow. It is strange that tesla or gm has not already been there done that. It never occurred to me that there could be that much (41%) fat in the system!

    • sault

      Well, before Tesla came around, it was strange that not one of the major car manufacturers had made a smoking hot sportscar like the Roadster. After all, Tesla only bucked down and did some hardcore engineering using mostly existing parts to make this happen. Or look at the Prius. While some aspects of the Hybrid Synergy Drive are revolutionary, there’s plenty of just “no duh” fuel saving methods employed on that vehicle. Many innovations don’t come out of the blue but are stumbled upon by people looking to design things that “just make sense” but haven’t really been tried before.

    • spec9

      It is still a debatable topic on whether Tesla’s decision to use cylindrical batteries is better than using prismatic batteries. Tesla seems pretty convinced that they are right . . . I’m not fully convinced.

      • Steve Grinwis

        Right now they have a huge cost and reliability advantage. It remains to be seen if having a more complicated pack design will still be a good design choice 10 years from now.

        Then again, Tesla is spending 400 million per year right now on R&D. That’s more than enough to spin up a new, simpler battery pack format if you need to. Given the modular design the have, it’s pretty simple for them to replace a their couple hundred bricks with a couple large format cells.

  • Jan Veselý

    41% of weight reduction means 69% higher kWh/kg number. That is really cool. And without the dark magic of battery electrochemistry. That’s jump from 250 kWh/kg to 423 kWh/kg with negative costs.

    • Boris Velky

      Hold your horses guys, all that matters is cost per kwh, I am sure Tesla is on top of their game.

      • Cost per kwh is far from all that matters. I believe lead-acid batteries still reign in the cost per kwh, but you don’t want batteries that heavy or voluminous or full-of-acid as they are in a car.

        • Steve Grinwis

          That’s creating a false dichotomy though isn’t it? It’s not cheap lead vs expensive lithium.

          I think what he’s going for is ‘Lithium Ion batteries are already dense enough, and cost is the barrier to adding more batteries to existing EV’s’

          Musk isn’t spending $5 billion to make batteries that are denser. He’s spending $5 billion to make batteries cheaper.

          • Boris wasn’t saying anything about density, which was my point. Lead acid may be cheap per KWh but it’s just not sensible for cars. So obviously cost per KWh is not “all that matters”.

          • Steve Grinwis

            It’s pretty clear he was talking about Lithium batteries from the context.

  • Matt

    Its called design for assembly. Less parts is almost always saves cost. And its double for screws, which take so much time to install. This is what happen when scale gets big enough, people send money to improve designs so they can make money.

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