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Power Transportation Technology

Solar Impulse Grounded Until 2016 25

Posted by samzenpus from the end-of-the-line dept.
An anonymous reader writes: The Solar Impulse 2 has been grounded in Hawaii for at least nine months because of battery damage sustained during its record 118-hour trans-Pacific flight from Japan. The project team says the aircraft is not expected to take off on the next leg of its journey until late April or early May 2016. The BBC reports: "...[the] plane experienced damaging overheating in its lithium-ion battery system. Although the battery units performed as expected, they had too much insulation around them, making temperature management very difficult. Engineers on the project have not been able to make the quick repairs that might allow Solar Impulse to have a crack at completing the round-the-world journey this year."
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Solar Impulse Grounded Until 2016 More

Solar Impulse Grounded Until 2016

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  • I admire their persistence. It's a cool project.

  • 9 months in Hawaii (Score:3, Funny)

    by Anonymous Coward on Friday July 17, 2015 @03:34AM (#50126563)

    What a *terrible* thing to happen.

  • Hey Elon! (Score:2, Flamebait)

    by xeno ( 2667 )

    Hey Mr. Tesla! Surely the Solar Impulse team would be happy to slap a very thin sponsor sticker on a prominent spot, in exchange for Tesla waking up some of its lithium-Ion gods out in the desert. Can't think of a better entity to say "let me look into that" and return 48 hours later with a station wagon full of the latest Li-polymer batteries formed in precisely the right shape with precisely the right chemistry.

    Maybe? I know Elon's other team needs a bit of a moral boost at this moment; why not get that

  • I've seen this up close (Score:5, Interesting)

    by cerberusss ( 660701 ) on Friday July 17, 2015 @03:57AM (#50126595) Journal

    I've seen this up close. I'm a software engineer and I've worked for a scientific institute in the past. One of the project involved putting a camera on a helium-filled balloon. The electronics and PC equipment (a PC104-sized Linux box) were powered from a big pack of lithium batteries.

    The problem is basically that lithium batteries perform best in a certain temperature range, say from 10 to 25 degrees Celsius (50 to 65 F). But that's rather difficult.When you lift off, it might be cold and you want the batteries to have a decent temperature. Otherwise they can't deliver enough power. So you insulate them and they stay warm by themselves, because when you draw power, they get warm.

    But then the higher you lift off into the air, the thinner the air gets. Thus convection will be less and less. You can shed heat via radiation (into the infrared spectrum) but that's only half of the heat or so. And then the insulation can overheat the battery packs.

    There's all sorts of tricks, for example copper-strapping the packs to a large piece of black metal so you increase the heat radiation. But if you automate that (or the insulation), you also get additional possible failures.

    What it comes down to, is some calculation but also some experience.

    • Re: (Score:2)

      by Rei ( 128717 )

      What's wrong with, you know, a simple thermostat-controlled fan, like most large battery packs use? Or if you want it to be passive, a greenhouse window opener to open up the insulation when it gets hot?

      I'm not faulting them for their oversight - bad decisions happen in every engineering project. But this doesn't strike me as any sort of unusual nor unexpected situation. News flash, temperature-sensitive batteries need proper temperature regulation rather than just being slathered in foam, details at 11..

      • Re: (Score:2)

        by tomhath ( 637240 )
        Power and weight. The plane could barely fly with what it had, they shaved every ounce of weight to get where they are.

      • Our first flight didn't end well due to another reason. The next balloon flight, the electronics engineer just removed enough insulation to keep it cosy at the height where the balloon would mostly stay. He then added a small additional battery pack connected to a heating element. A colleague coded a PID algorithm to keep the big pack warm at the start of the flight.

    • They could simply run some air duct tubes through the insulation near the batteries, then open/close dampers as needed. Very little energy used or added weight required.

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