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    On The Job

    A123 engineer making batteries better, bigger

    Greg Tremelling inside a truck container built for a large-scale battery system.
    Michele McDonald for The Boston Globe
    Greg Tremelling inside a truck container built for a large-scale battery system.

    It’s difficult to build a battery that holds a charge for long periods — especially when materials are potentially unstable. It can be even tougher when you’re developing batteries large enough to store electricity for the power grid.

    But that’s the job of Greg Tremelling, 31, an electrical engineering manager who leads the big battery team at A123 Systems Inc. of Waltham.

    Tremelling’s team focuses on applications for commercial transportation and large-scale energy storage, helping to create battery configurations that can power hybrid buses or allow operators to pull more energy from wind farms and solar generating plants.

    How do lithium batteries work?


    Most people think of lithium batteries as the type that power laptops and cellphones, and not a commercial-grade workhorse. A123’s lithium batteries are based on nanostructured electrodes, where the chemistry of the cells has been configured to allow a lot of electrical charges without wearing out.

    How did you develop batteries for wind farms and solar that help cope with energy fluctuations?

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    We brainstormed about what sort of containers could hold over 80,000 cells for the battery. The answer was a 53-foot shipping container that we outfitted with insulated wire, electrical panels, and cooling pipes, which became the perfect package to hold the battery. A West Virginia wind farm today has 16 of these trailers outfitted as batteries.

    How did you get started in battery technology?

    After graduating from Worcester Polytechnic Institute, I went to work at American Power Conversion. Then someone invited me to check out this tiny start-up in Hopkinton, which A123 was at the time. I’ve been with the company since the end of 2006.

    What have been some new battery developments at A123?

    One of the technologies was done on the Formula One circuit, integrating a hybrid power boost system into a race car. Using batteries at certain points around the track, the driver was able to hit a button and add a large boost to the horsepower of the car.

    Have you visited factories where lithium ion batteries are manufactured?

    I’ve been to China and gone through factories, seeing clean room areas, visiting suppliers, and trying to improve battery manufacturing processes.

    Have you ever driven a Tesla?


    I’ve never driven a Tesla, but I did test a car made by Norwegian electric carmaker Think.

    Do you tinker in your spare time?

    I do. I’m always looking for a project. Most recently, I converted an old snowmobile into what looks like a chopper motorcycle. It has a single ski in front but a snowmobile drive train in the back. It did actually work.

    Cindy Atoji Keene can be reached at