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Bench Test Results: Sherlock Hohm 28.4A 2782mAh 20700...a 25A battery, worse than 5-leg top contact

Discussion in 'Batteries and Chargers' started by Mooch, Mar 22, 2018.

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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, LG, Panasonic, 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 protected battery pack. Never exceed the battery’s continuous current rating and keep the plastic wrap and top insulating ring in perfect condition.

    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.

    E7DF1BC8-CFD8-423E-B290-39A39D1D5EFA.jpeg 1AD803B6-513A-43C4-8E47-536D0AAB5161.jpeg BBDFED0D-6F3C-4C9E-8BD6-6D77A8AF457A.jpeg CC1F2CA0-1762-4C28-968E-41D93E7620B5.jpeg


    Bottom Line
    This is a cell that runs at close to 90°C at its 28.4A continuous rating. This is too hot in my opinion for decent cycle life as most cells, including all of the others from Hohm Tech, say not to exceed 75°C-80°C. When the datasheet becomes available I will be able to check its max temperature rating.

    The Sherlock Hohm cell performs worse than the 5-leg top contact 20700’s but better than the 4-leg iJoy 20700.

    The two cells I tested delivered 2760mAh and 2761mAh at 0.5A down to 2.5V. Considering the differences in the equipment used by Hohm Tech and I these cells can be considered to have met their 2782mAh capacity rating.

    The Terms & Conditions section of Hohm Tech’s web site says that their cells are not meant for use outside of a protected battery pack or in a device without equivalent protection. This means no unprotected mod or mechanical mod use of their cells is supported by Hohm Tech. For vendors this might affect the warranty in certain situations. Contact Hohm Tech for more information about this.

    I was very disappointed to see “47.8A” featured in a large font on the cell, with nothing to indicate what it meant. This is the pulse rating, which Hohm Tech defined for me in emails, but Hohm Tech says that vapers should not use this pulse rating for anything. They said we should only use the continuous discharge rating...and I agree.

    The continuous discharge rating is also on the cell, and is marked as “CDR”, but uses a smaller font. Hohm Tech said that in December 2017 they decided to switch the sizes and positions of the two ratings on the wrap. I don’t know if these new wraps are being used yet.

    I am estimating the ratings for this Sherlock Hohm cell to be 25A and 2782mAh. The 25A rating helps to keep its temperature down closer to the 80°C limit for other cells.

    Two cells were donated for the purposes of testing by Hohm Tech (http://www.hohmtech.com). Thank you!


    Continuous Current Discharge Graphs
    487DF1F3-1F80-4E49-B797-36F7E8A5F617.jpeg 005CF8D6-31F6-4341-97E7-C961FB51E06C.jpeg


    Ratings Graphic
    5F3B827A-798F-46AF-B865-7F1AA754133C.jpeg


    Hohm Tech Terms & Conditions about only using in packs and protected devices
    9ABB7CD5-842D-471D-A14A-0FB0E24D4ACD.jpeg


    Performance Specs
    • DC Internal Resistance = 23.3mOhms (milliohms) average for the two cells.
    • Total energy delivered down to 3.2V at 10A continuous = 8.1Wh (Watt-hours) average
    • Total energy delivered down to 3.2V at 20A continuous = 5.4Wh (Watt-hours) average
    • Total energy delivered down to 3.2V at 30A continuous = 1.0Wh (Watt-hours) average
    To see how other cells have tested check out this link: https://www.e-cigarette-forum.com/forum/blog-entry/list-of-battery-tests.7436/
     
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  2. Rossum

    Rossum Surly Curmudgeon Verified Member ECF Veteran

    Supporting member
    Dec 14, 2013
    NE FL
    Three significant figures in the printed (and inflated) current ratings? Four significant figures in the mAh capacity rating?

    Do they not understand how silly this is?
     
    • Agree Agree x 2
    • Like Like x 1
  3. Robin Becker

    Robin Becker Senior Member

    Feb 3, 2018
    Berlin
    Funny name and nice idea, however so much nonsense like:
    "Reformulated using its little sibling’s Hohm Work foundation, but with 1.3% greater nickel (Ni) concentration per unit of measure" - I doubt, if they even know the exact chemistry of the cell
    or:
    "EPTC (Enhanced Positive Thermal Coefficient) equipped: Reduction in Thermal Runaway potential" - High-Current batteries don´t have PTC
    or:
    "NiCo Meld process ensures charging rates up to 3.15A" - every battery (almost) is cable of charging up to 2C, so what is the big-deal?
    I would like to finish with Clint Eastwood: "when you have to shoot, shoot...don´t talk"
     
    • Like Like x 4
  4. KenD

    KenD Vaping Master ECF Veteran

    Aug 20, 2013
    Stockholm, Sweden
    Hohmtech have a history of shoveling out a lot of convoluted bs.

    Sent from my Thor E using Tapatalk
     
    • Like Like x 1

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