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Bench Test Results: Lithium Werks 30A 1100mAh LiFePO4 18650...best stacked mech battery, but...

Discussion in 'Batteries and Chargers' started by Mooch, Nov 13, 2019.

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  1. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    These tests below only note the ESTIMATED ratings for these batteries at the time I tested them. Any battery that is not a genuine Samsung, Sony, Murata, LG, Panasonic, Molicel, or Sanyo can change at any time! This is one of the hazards of using “rewrapped” or batteries from other manufacturers so carefully research any battery you are considering using before purchasing.

    Misusing or mishandling lithium-ion batteries can pose a SERIOUS RISK of personal injury or property damage. They are not meant to be used outside of a physically and electrically protected battery pack. Never exceed the battery’s current rating and keep the plastic wrap and top insulating ring in perfect condition. Use of any of these batteries is AT YOUR OWN RISK.

    Testing batteries at their limits is dangerous and should never, ever, be attempted by anyone who has not thoroughly studied the dangers involved, understands the risks, has the proper equipment, and takes all appropriate safety precautions.

    If the battery has only one current rating number, or if it only says "max", then I have to assume the battery is rated at that current level for any type of discharge, including continuous.

    18FC2D0B-9CC5-4C44-9492-188ADC280782.jpeg E179AE54-741D-4D2B-9D54-4B39C3A83F03.jpeg 8E73F3DE-5B06-4674-A270-307C6961A726.jpeg E2ADB4A0-30BF-4D32-91AD-04520D87A84F.jpeg 9E89D693-93F5-44CF-A23B-92C2C9FB48EB.jpeg


    Bottom Line
    This is a great performing LiFePO4 cell that is easily the best 18650 choice for those who want the most consistent vaping experience in a stacked (series) mech. But there are a LOT of things to consider before buying them.

    LiFePO4 chemistry cells, lithium-ferrous-phosphate (LFP), move lithium ions back and forth inside the battery the same way as done inside the batteries we normally use. But the materials that are used inside the positive part of a LiFePO4 battery, the “chemistry” of the battery, are different. These cells license the technology developed by A123 Systems.

    Because of these different materials, LFP cells perform differently than the cells we normally use. Here are a few advantages and disadvantages for LFP:


    Advantages:

    Extra safety – LFP cells are harder to force into thermal runaway if abused and if they do go into runaway the reactions are a lot less violent and at a much lower temperature. Typically, there are no flames.

    High power density – LFP cells often have very high current ratings for their size.

    Consistent voltage when discharging – Most of the discharge is spent at about the same voltage. The li-ion cells we normally use drop their voltage a lot more as they discharge. This makes for an inconsistent vape for a mech user and forces them to switch batteries more often. LFP cells give a mech user a much more consistent vape until the cell is almost empty. They are a fantastic choice for a consistent vape.

    Long cycle life – LFP cells typically have an overall life expectancy at least several times longer than the li-ion cells we normally use.


    Disadvantages:

    Lower charging voltage – They must be charged to 3.6V, not 4.2V.

    Lower discharging voltage – LFP cells run at 2.0V to 3.6V and cannot be used in a typical regulated mod due to their lower voltage. Only regulated mods using Evolv DNA or Dicodes boards, properly set up for this battery chemistry, can be used. Mech users need to use coils suitable for about 2.5V to 3.0V (depending on how hard they are using these cells).

    Lower capacity – LFP cells have a lower “energy density” than the other li-ion cells we use. This means they have lower capacity ratings, e.g., the Lithium Werks 18650 is rated at only 1100mAh.

    So there are some real advantages to using LFP chemistry cells like the Lithium Werks 18650 and 26650, especially for mech users, but the disadvantages need to taken into account.

    A series set of the Lithium Werks cells would run at about 5.2V to 5.0V, a 0.2V range, for most of a 30A discharge. A series set of Samsung 20S cells would run at about 6.4V to 7.2V, a 0.8V range, for most of the discharge. That is a huge difference and demonstrates how “flat” and consistent the discharge curve is for LFP cells. As good or better than good performing pouch LiPo cells.

    Personally, I think that LFP cells are a fantastic choice for use in a stacked/series mech. Sure, you can use them in a single battery mech if you vape at lower power levels. But running a pair of them at 5.0V - 5.6V or so at 20A-30A can give you a heck of a great vape with all the added safety benefits LFP cells offer. You just need a charger capable of charging to 3.6V. I recommend one you dedicate to only charging at that voltage though. This will prevent any accidental charging to 4.2V if you also use regular li-ion batteries too.

    The one thing I was really wondering about was how much gas LFP cells would release during thermal runaway versus the cells we normally use. This is a big issue if a cell goes into thermal runaway inside a tube mech as it’s all the gas that is produced that causes the mech to “rapidly disassemble”.

    The paper linked to below indicates that not only is the temperature during runaway of a LFP cell a lot lower but the amount of gas is a lot lower and it is released a lot slower, over a period of about 30 seconds versus less than a second for the other two chemistries tested: https://pubs.rsc.org/en/content/articlepdf/2014/ra/c3ra45748f. This is great news.

    While this does not mean LFP cells are “safe” it’s great to see that we have a safer option to use when vaping, even if there are some disadvantages to deal with.

    If you’re feeling particularly masochistic there’s a great article detailing why LFP can be a safer chemistry to use: https://lithiumwerks.com/wp-content/uploads/2019/08/Electric-Hybrid-Marine-Apr-2019-article.pdf

    These papers also discusses the increased safety of LFP cells:
    http://interface.ecsdl.org/content/21/2/37.full.pdf
    https://res.mdpi.com/d_attachment/batteries/batteries-03-00014/article_deploy/batteries-03-00014.pdf

    The capacities for the two cells I tested were 1199mAh and 1207mAh at 220mA (0.2C) down to 2.5V. This if fantastic consistency! I am rating these cells at 1100mAh.

    These cells run at a very low voltage compared to our regular Li-Ion cells but they show absolutely no signs of stress at 30A. I am rating them at 30A.

    Two cells were donated for the purposes of testing by 18650batterystore.com. Thank you!


    Continuous Current Discharge Graphs
    0F5BC077-3A61-4D12-B287-83543A43D6A2.jpeg


    Ratings Graphic
    5E7372C3-B267-4889-A645-1260E7BE4ACC.jpeg


    Performance Specs
    - DC Internal Resistance = 15.4mOhms (milliohms) average for the two cells.
    - Watt-hours (energy) delivered at 10A down to 2.5V = 3.3Wh
    - Watt-hours (energy) delivered at 20A down to 2.5V = 3.1Wh
    - Watt-hours (energy) delivered at 30A down to 2.5V = 2.7Wh

    I want to work for the vaping community full time! If you feel what I do is worth a couple dollars a month and you would like early access to battery availability, battery and charger testing and news, and a say in what I test, then please consider becoming a patron and supporting my testing efforts: Battery Mooch is creating battery tests and educating vapers | Patreon.

    To see how other cells have tested check out this link: List of Battery Tests | E-Cigarette Forum
     
    • Informative Informative x 3
    • Like Like x 2
  2. Rossum

    Rossum Surly Curmudgeon Verified Member ECF Veteran

    Supporting member
    Dec 14, 2013
    SW VA
    This is the real rub for most people. That's roughly 1/3 of the energy of a normal li-ion cell.
     
    • Like Like x 1
    • Informative Informative x 1
  3. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    There’s always a tradeoff when it comes to batteries. :)
     
    • Agree Agree x 2
    • Like Like x 1
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