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Thread: Hoverboard Battery issues with 18650 cells

              
   
   
  1. #21
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    RE: "If you can cut a corner, the Chinese manufacturing industry will find it."

    I was told that the no-name caps cost $.08 to $1 each, whereas the big-name brand is $6-$8 each.

  2. #22
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    RE: "because the lithium batteries are a "no fly" item? "

    The problem is the BMS on multi-cell packs. Or, with the two quadcopters I had, single-cells that needing to be squished, with no hardcase like a cellphone battery.

    FYI, there is a "distinguished" PhD on the net, with his view on the hoverboard fires. He stated that Lithium cell separators will leak, over time. And eventually, there is a fire. The more you charge/discharge, the more likely.

    Also saw statistics somehwere that nearly 10 percent of LiPo battery packs had an "incident" of some kind. (Could have been made up statistics by the enemies of electric vehicles and hoverboards. Just the same way the Zappy electric scooter tidal wave/trend was "tripped up" by persons unknown.)

  3. #23
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    Quote Originally Posted by NonPolluter View Post
    FYI, there is a "distinguished" PhD on the net, with his view on the hoverboard fires. He stated that Lithium cell separators will leak, over time. And eventually, there is a fire.
    Sounds like BS to me - link?

  4. #24
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    Quote Originally Posted by NonPolluter View Post
    Most nobbyists are enamored with Lithium, despite the sole long-term success of the Tesla car, due mainly to limiting the battery pack's usage to between ~30 percent to ~85 percent of capacity.
    ..and the Leaf, the Volt, the Zoe, the Fluence, the Kangoo... hell even the Reva-i (G-Wiz).
    and the overhead in the leaf about 10% total - the pack is 24kWh rated and 21kWh usable - oh, and I've 170000km done in my one and it hasn't caught fire yet, so yeah, pretty stable.

    Quote Originally Posted by NonPolluter View Post
    The resellers are also not really telling everthing about LiFE batteries, either. I have owned 3 LiFE 'cycles and the power is very greatly diminished when ambient temperature is colder than 6 Celcius. Even worse, apparently the LIFEPO4 batteries are "hurt" permanently if they are charged when temperature is colder than 5 degrees Celcius. So, what good is an electric bike, or electric scooter, in the winter?
    All batteries loose capacity in colder conditions - *all* - that's not a lithium exclusive trait.

    And as to the significance of any additional degredation in cycling the battery on account of thermal conditions - I'd really love to see some quantitative data on the matter because, whilst yes, it is a factor, it's merely one of a number and over the timescales that you're talking about it being done in the course of a year, I'd be very slow to concede that there aren't far bigger elements to that equation.

    Now as to older battery tech - there may well be a place for some of them going forward, but if you're going to try and suggest that *any* Pb tech is going to outperform Li, then you'd really want to be following that up with some credible academic or industry material. It's very easy to say that a sealed-Pb battery can run a drag race, sure, they can produce the amps, but what's their endurance? mass? volume? cost? lifecycle? charge requirements? ...etc... The point being that there's a whole spectrum of requirements to be met.

    Bottom line is this - the only reason that other battery techs are safer than lithium is because they aren't as energy dense or as power capable; put another way, they're lower performance options - they simply don't pack the same amount of energy into the same amount of space with the same ability to release that energy.

    Many other techs can do two of those three things, but no other solution does all of them, and when another solution does come along, it'll require similar respect.

    Pb will still have it's place, not doubt about it, but it won't be in anything related to tranport.

  5. #25
    Seņor Member podolefsky's Avatar
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    Charging at low temps definitely hurts cycle life. The anode becomes too cold to accept lithium and you get lithium plating. Lithium plating is also what causes reduced cycle life in general, but it's accelerated significantly at temperatures below 0C. You can also get dendrite formation which leads to internal shorts.

    There are additives used in some cells that allow charging below 0C. You need to keep the charging rate low to make sure the anode can accept li faster than it is being deposited (C/10 is a good target).



    (From http://www.mpoweruk.com/lithium_failures.htm )

    Plenty of scholarly articles on this, unfortunately you need journal subscriptions to read most of them.

    https://scholar.google.com/scholar?q...PsB3kQgQMIGjAA



    Also, lead acid isn't actually safer than li-ion. You can get thermal runaway in Pb. They also release hydrogen-sulfide gas (H2S) which is poisonous and flammable. This includes "sealed" Pb - they won't spill sulfuric acid, but they will vent H2S.
    - Noah Podolefsky -
    The GSX-E

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  7. #26
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    I was aware of the effects of charging cold alright - what I was looking for was a quantitative value on the actual effect.

    We're all great here (and elsewhere) at saying that this hurts the battery, and that hurts the battery, blahdy-blahdy-blah... but frankly, charging under any circumstance hurts the battery, hell, NOT charging hurts the battery too - so the point I'm getting as it what's the quantifiable effect?

    Is it 10% more degredation per cycle?
    Is it 50%?

    ...and then how much degredation is there per cycle to begin with?
    are we talking about an additional 50% of 0.003%?

    Relative metrics are great for getting people whipped up into a frenzy this way but what does it ACTUALLY amount to?

  8. #27
    Seņor Member podolefsky's Avatar
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    Quote Originally Posted by Spoonman View Post
    Is it 10% more degredation per cycle?
    Is it 50%?

    ...and then how much degredation is there per cycle to begin with?
    are we talking about an additional 50% of 0.003%?

    Relative metrics are great for getting people whipped up into a frenzy this way but what does it ACTUALLY amount to?
    That's why I posted the chart. It depends on chemistry, additives, etc. But as an example, that chart shows 50% reduced cycle life at -20C, and at -40C you essentially kill the cell in one cycle.

    None of this is absolute, since even for the same exact cell the cycle life can double or triple, or halve, depending on DOD during each cycle, high and low voltage limits, temperature, etc. But, usually you're talking 1000-2000 full cycles, so about 0.05-0.1% degradation per cycle. If you limit capacity with very conservative voltage limits (e.g., Tesla), you can get over 3000 cycles with some cells.

    Note that "cycle life" is usually rated for 80% of capacity remaining. So an "end of life" pack still has a lot left to give.

    Agreed, people get whipped into a frenzy over all sorts of things lithium battery related.
    Last edited by podolefsky; 04 January 2016 at 1121.
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    The GSX-E

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  10. #28
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    I have torn apart about 60 of these packs for reusing som fresh cells. It is samsung icr18650-22p and the dates are different on each cell so I dont think its a rewrapped chinese crappy cell. But the weldings and soldering are very crappy and the bms is lowest quality. Inside the hoverboard all cables goes thru the moving part in the middle and cables are not protected.
    It could be a great product but the chinese manufacturer did a bad job as always.
    Hire a german or japanese qualitycheck and the problem is solved.

    Skickat från min E5823 via Tapatalk

  11. #29
    Junior Member nucciosan's Avatar
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    Hi all
    The low quality can be accepted if balanced by low costs, but when it involve our safety it is very very important extensive controls on every product.
    Non only Lithium batteries are involved in fire risks, luckily at today we (me and my friends) don't have experienced fire on batteries, but we had on controllers.
    We have some pictures of "made in USA" burned controller
    Quantya-Controller-Fired.jpg

    I have no doubt about good quality of this controller. But It had many years of use (about 7) without too much care.
    I want to say that talking about electric vehicles there are risks even with products of good quality.
    Imagine how much risk using products of poor quality.

    One of my friend have 3 Quantya Freeride and Strada, he purchased used some year ago (I think are 2009/2010 models).
    He use it for rent in his farm near Milano and have no time to maintenance it so the bikes are often abandoned as they are after the use in the Woods.
    All his motorcycles have had problems with the batteries, but only involved the BMS, not the battery cells.
    The main cause of the malfunction is the minimum current consumption of the BMS.
    Leaving the battery discharged for several weeks, the minimum comsuntion of the BMS discharged some cells lower to 2.4/2.5 Volts.
    Fortunately the cells do not ruin and just recharge them with a small battery charger and everything returns to normal operation.
    Also the BMS (Made in Swizzerland) went dead on 2 batteries, but all cells are saved.

    I repaired it with the new BMS16 purchased at Chargery.com
    With a little interface that I built the BMS16 can control the HiperFets on the original Quantya power card.
    This are some picture of my modifications.
    Quantya-New-Balancer.jpgQuantya-BMS-interface.jpgQuantya-New-BMS-Chargery-Tests.jpg

    My balancer is of the passive type and absorbs about 1A with a control on the voltage +-1mV.
    Hope these info are useful to someone.
    Greetings

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