Possible Group Buy - Check Interest - Lithium Titanate cells

Discussion in 'Hobby Engineering' started by rainwulf, Jul 15, 2018.

  1. rainwulf

    rainwulf Member

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    A mate and me are looking at getting a group buy together for 40ah LTO cells from china.

    I am wondering if anyone would be interested in getting some.

    Specs:
    Model OSN-LTO-66160H
    Materials LTO
    Nominal capacity 40Ah
    Nominal voltage 2.3 V
    Dimension
    Length: 160±1.5mm
    Diameter: 66±1mm
    Weight 1.24±0.1kg
    Internal Resistance ≤1mΩ

    Operating voltage
    Charge cut-off voltage 2.8 V
    Discharge cut-off voltage 1.5 V
    Standard charge/discharge current
    Charge current 1C(40 A)
    Discharge current 1C(40A)
    Maximum charge current 10C
    Maximum discharge current 10C
    Cycle life 30000 times
    Operating Thermal Ambient
    Charging -50℃~ 65℃
    Discharging -50℃~ 65℃
    Storage Thermal Ambient Short term(within 1 month) -20℃~ 45℃



    36usd EACH - BEFORE shipping, shipping will obviously depend on the number we order. The more we order, the cheaper it will get both in volume discount and shipping , if we can get a indicative number we can get a quote.

    6 of these will match a lead acid battery of around 80ah capacity, but be 1/3 the weight, and have a massively longer life time.

    Pros: Massive current capacity and lifetime compared to lithiums.

    Cons: Lower full cell voltage which means you need more of them to get the voltage you need. However - lead acid management systems will work with these as 6 cells in series are a perfect replacement for a SLA/Flooded battery.



    We are initially getting 24 in for testing and experimentation in the next month or two, we will be creating a pack for a ute based power pack to replace SLA.

    We will also be using that time to look at what balancing systems are required. If needed we might look at the systems that supercap banks use for charge equalisation.


    More info on LTO:

    The Lithium Titanate (LTO) battery
    This technology is known for its very fast charging, low internal resistance/high charge and discharge-rate, very high cycle life, and excellent endurance/safety. It has found use mostly in electric vehicles and energy storage (Toshiba, YABO, and Altair Nanotechnologies), and wristwatches (Seiko). More recently, it is beginning to find use in mobile medical devices due to its high safety. One underlying reason for this technology's characteristics is that the chemistry uses nanocrystals on the anode instead of carbon, which provides much more effective surface area. Unfortunately, however, this battery has lower terminal voltages than other Lithium types.

    • Specific energy: approximately 30-110Wh/kg
    • Energy density: as high as 177 Wh/L
    • Specific power: 3,000-5,100 W/kg (peak load)
    • Discharge efficiency: approximately 85%; charge efficiency over 95% (low-rate)
    • Energy/consumer-price: 0.5 Wh/dollar
    • Service or shelf life: >10 years (some to 20 years)
    • Self-discharge: 2-5 %/month
    • Cycle durability: 6,000 cycles to 90% capacity (some models >10,000 cycles)
    • Nominal cell voltage: 1.9 to 2.4V (Toshiba SCiB cells 1.5-2.7V operating; 2.3V nominal)
    • Cut-off voltage: 1.5V typical (some at 1.7V)
    • Temperature: -40 to +55°C (extended models)
    • Charging technique is using standard constant current, followed by constant voltage until the amps threshold is reached.
     

    Attached Files:

    Last edited: Jul 15, 2018
  2. Mathuisella

    Mathuisella Member

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    Interested here.
     
  3. OP
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    rainwulf

    rainwulf Member

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    How many? I am getting 12 to have a play with them on my solar system, and probably end up making a camping battery out of them.
     
  4. Mathuisella

    Mathuisella Member

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    At the moment all my funds are going into the car. So if you are thinking of the next few weeks orderimg, i couldn't join in.

    Consider me a bystander on this group buy for now.
     
  5. jimbogimp

    jimbogimp Member

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    funny comment
    I'm pretty tempted for 6. Put me down as a "highly likely" and if it gets closer to going ahead I'll confirm 100%.
    I'm happy to wait for math to get his funds in order :)
     
  6. OP
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    rainwulf

    rainwulf Member

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    Yea we are looking at maybe in a months time.
     
  7. aXis

    aXis Member

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    Very tempting but I'm in WA, postage would suck.
     
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    rainwulf

    rainwulf Member

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    They aren't that heavy, we will be getting more info as the time comes closer. These batteries are fantastic, so far there will be 18 ordered, as i want to get a bank for 24 volts to test on my systems.
     
  9. OP
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    rainwulf

    rainwulf Member

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    Ok, now 24 ordered which is above the minimum size. awesome.
     
  10. aXis

    aXis Member

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    Specs say 1.2kg each, and I'd probably want 12 for a 24V system. With packaging that's pushing 30kg, so looking like $100+ in courier costs. :(
     
  11. jimbogimp

    jimbogimp Member

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    funny comment
    Couriers can be strict on shipping them as they could be classed as dangerous goods too so just be careful/aware of that (I'm in NSW BTW)

    I really need 60ah + for my camping setup, so I could actually be keen for 12 cells pending final price.
     
  12. OP
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    rainwulf

    rainwulf Member

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    We are currently talking to a company in china that may be able to ship them to us for cheap. The shipping prices are actually higher then the costs of the batteries, so we are trying to find the best value.
     
  13. Sunder

    Sunder Member

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    I ordered a fairly large order from these guys.

    Don't forget to add 10% GST, 5% duty and a small customs handling charge.

    Too soon for me to need more, but next time I order a set, I should offer a group buy as well.
     
  14. OP
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    rainwulf

    rainwulf Member

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    we aren't on any tight timeframe as of yet, but the more the merrier i assume haha
     
  15. Sunder

    Sunder Member

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    From memory, getting to the next band takes $1usd off each cell, and $1.30 off the shipping of each cell.

    So not massive savings, but enough. To get really big discounts on shipping, you need to get to the pallet level. Good luck hitting that, unless you find 5-10 people wanting to go fully off grid.
     
  16. OP
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    rainwulf

    rainwulf Member

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  17. OP
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    rainwulf

    rainwulf Member

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    Well we got an initial pricing.. and its not pretty. Costs more then the cells to ship them. Ends up around 500 dollars for 6 cells. Just under 100 a cell.
     
  18. aXis

    aXis Member

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    Ouch!
     
  19. jimbogimp

    jimbogimp Member

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    funny comment
    Wowser. Shipping is a killer. :upset: I think I'm out for that price I'm afraid. On top of that we've got local shipping and the cost of a BMS. It's still a FAIRLY good price though compared to what's available locally. But I'll probably just end up spending a bit more grabbing something closer to what I need ~ 60ah with a local warranty and such.
    Thanks for looking into it though rainwulf! :thumbup:
     
  20. Sunder

    Sunder Member

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    This is what I paid:

    Battery Price.png

    There is a remote possibility I would want to place an order of the same size in the next 6 months, in which case, getting a GB of 40 more, and the unit price goes down to $17 per cell, and the shipping drops $1.30, from memory.

    If people are interested at that price point, then I am happy to run the GB. I also have 70ish cell protectors (NOT full blown BMSes) that I don't want, if people are happy to do more of their own monitoring (Remembering that LTO don't catch fire. Worse case, you puff them).

    On the other hand, if someone wants to build an electric motorcycle that looks like a Postie Bike, but performs like a Hayabusa... That's what I'm using them for :) I want to convert a Honda CBR250R, or a Kawasaki Ninja, into a beast that has 350nm from launch. That's not a typo. My friend thought I meant 35nm, which is like a 50% increase. No, I actually mean three hundred and fifty newton metres.

    Edit: Just noticed you were going the 40Ah versions, not the 30AH versions, so my cells aren't that comparable. They're flat pouch cells with 28-29Ah. However, being flat, they're cheaper to send.
     
    Last edited: Jul 28, 2018

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