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This cell just has a 40A “max” rating on the wrap but looks and performs identically to the Samsung 25R, a cell rated at 20A. To add to the confusion, Efan’s Alibaba web page seems to list this as a 35A continuous cell.
Efan says that they are rewrapping this cell, giving it a 25A continuous rating and a 40A “max” rating. But 25A continuous is also an exaggerated rating as it heats the cell to over 90°C. That is too high a temperature to allow for decent cycle life.
The datasheet says the 40A rating is a “Max Short Time Discharging Current” rating. Efan says this time is a “few seconds” but the rating is useless without knowing the length of the pulse, the time between pulses, and the criteria used to set the rating (temperature? voltage sag? cycle life? A combination of those?). I was unable to get Efan to give me this information.
Efan denies that this is a rewrap but I examined the cell with a loupe, even looking at the bend radii and metal thicknesses of the top contact structure and the tooling marks on the cell, and this Eizfan is identical to the 25R. It performs the same and is also the same size and weight as the 25R.
Something I don’t talk about nearly enough…the incorrect use of “IMR” on so many rewrapped cells. This Eizfan does not use the LMO (lithium-manganese-oxide) battery chemistry associated with the “IMR” model number prefix. The Samsung 25R uses NCA chemistry (nickel-cobalt-aluminum).
The capacity for two of the four cells I tested was 2568mAh and 2572mAh. This is fantastic consistency and typical of cells from the large OEM manufacturers like Samsung, Sony, etc. China manufactured cells usually have much worse cell-to-cell consistency.
I am giving this cell ratings of 20A and 2500mAh.
Four cells were donated for the purposes of testing by Efan (https://yi-fang.en.alibaba.com). Thank you!
Ratings graphic: https://imgur.com/a/zWU9kux
Test report: https://bit.ly/2Qwvq3h
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These tests 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” batteries 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.
Any rating in my ratings tables can change at any time as different grade cells appear on the market, we get swamped with fakes, or new information becomes available to me. Please, never assume that the ratings in the tables are permanent and will never change! Always download the latest version before considering any cell purchase.
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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