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Thread: LiNiMnCoO2 Batteries

  1. #1
    callumhoy's Avatar
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    These types of batteries are commonly found in power tools, such as the new Argos simple value drills.
    Shakey said in his breakdown of the drills:
    "They are LiNiMnCoO2 batteries, the most common type used in powertools. Safer than LiPo, not quite as safe as LiFePo4. However not on the FRA's approved list, I move that this battery chemistry should be tested. It is in the roboteers interests to have such a common battery type available to us."
    (http://www.fightingrobots.co.uk/thre...ide-and-review)

    Does this mean we are currently not allowed to use these batteries? And is there any chance of them being tested and approved any time soon?

  2. #2
    Theo's Avatar
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    I've been told by Shakey I think that the high up FRA admins are currently debating them. It was a few months ago and the rules are the same, so I'm guessing they weren't approved.

  3. #3
    Still normal LiPo batteries, just with a few dashes of extra elements.

  4. #4
    overkill's Avatar
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    Are these not just an update of the older lithium-manganese batteries that didn't work out 10 years ago? They had lower discharge capacity and energy density than the mainstream Lipo cells of the day and cost more.

    As Mario says, they just added cobalt and nickel to the battery cathode to get better performance but are basically quite old technology.

  5. #5
    Garfie489's Avatar
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    Quote Originally Posted by maddox10 View Post
    Still normal LiPo batteries, just with a few dashes of extra elements.
    However would they require LiPo bags? - guessing not considering their usual applications.
    My 3 loves - Rugby, Racing, and Robotics.

  6. #6
    McMullet's Avatar
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    First time poster here. I'm a robot noob but I have worked in the business of lithium batteries for a decade or so now.

    As others have said here's no fundamental difference between lipo and (what are commonly referred to as) Li-ion batteries, it's just packaging. All Li-ion cells are a carbon anode with a cathode composed of oxides of cobalt, nickel, manganese or a mixture thereof. Lipos are just Li-ion cells in a soft plastic/aluminium laminated encapsulation, sometimes with a gel to stabilise the electrolyte.

    All lithium-ion cells can go into thermal runaway, which is a very rapid exothermic reaction leading to high temperatures (>1000°C possible) and lots of gas. The gas is poisonous and they can produce a lot of heat and flames but as long as you keep your distance and ventilate there's no real danger.

    The cylindrical cells you get in a drill or other consumer item are in solid steel cans, which means that rather than just releasing smoke as lipos do (because they pop like balloons at low pressure), the gas builds up inside until they explode. There are safety vents but they can't usually cope with the rate of gas generation and the can ruptures. A bag will not help you here. The word explode is not an exaggeration. Example:
    The initial "event" there is probably just one cell, I would guess an 18650.

    It's true that NMC Li-ion are generally harder to get into TR than pure cobalt, but they still go eventually. They just need to get a little bit hotter. Severe damage would be enough to set one cell off, and the heat would then ignite the rest of the pack.

    Overall it would be very hard to "prove" NMC batteries to be safe. Partly because it would involve some potentially dangerous testing, partly because it can cover so many things - different cell sizes, can designs, actually completely different chemistry (different proportions of Ni, Mn and Co).

    (This is a good resource on battery types: http://batteryuniversity.com/learn/a...of_lithium_ion )

  7. #7
    overkill's Avatar
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    Interesting info! An accident prone friend had an A123 cell explode in his robot - it didn't involve much fire but made a terrible mess. I once had a large Nicad pack short internally, leading to all the tabs melting off and the electrolyte boiling and venting; when it comes to batteries, safety is a relative term .

  8. #8
    If a LiPo explodes in one of our machines during combat, it's a great show.

    But that seems to be rare, even if we all try to get the best results on the opponent.

  9. #9
    McMullet's Avatar
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    Yeah I think a LiPo fire is a nice safe show!
    In British cultural terms, LiPo is the bonfire and cylindrical cells are more the fireworks...

    Quote Originally Posted by overkill View Post
    Interesting info! An accident prone friend had an A123 cell explode in his robot - it didn't involve much fire but made a terrible mess. I once had a large Nicad pack short internally, leading to all the tabs melting off and the electrolyte boiling and venting; when it comes to batteries, safety is a relative term .
    Was that a nano-phosphate cell? I guess the definition "safe" is "the nasty stuff mostly stays inside the robot"...

    At the end of the day batteries are just chunks of poison that store a load of energy - the energy wants to get out and if it does so too quickly it will get very warm and distribute the poison over a wide area. Don't be too hard on batteries though, petrol tanks aren't that different.

  10. #10
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    Quote Originally Posted by McMullet View Post
    At the end of the day batteries are just chunks of poison that store a load of energy - the energy wants to get out and if it does so too quickly it will get very warm and distribute the poison over a wide area. Don't be too hard on batteries though, petrol tanks aren't that different.
    You should put that last paragraph in your forum signature.

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