Mooch’s Bench Test Results: Samsung 40T3 35A 4000mAh 21700...latest version of the 40T

Test Report Summary: This is the newest version of the great performing Samsung 40T. It can be identified by a “3” at the start of the third line of printing on the wrap (see photo below). The 40T1 had no separate number at the start of the third line. There was no 40T2.

Photos, Graphs, Ratings Graphic: Imgur: The magic of the Internet

The 40T3 also has the new “FIRE HAZARD! NOT FOR VAPE!” warning printed on the wrap. All of the Samsung round cells we buy will eventually have a warning like this. Nothing in the cells has changed though. This warning is, IMO, just being added to cover Samsung legally since round cells are never supposed to be used outside of a fully protected battery pack. We use them at our own risk.

The 40T3 uses the new metal can codes too. The top line of code printed on the can should be “N40T” for all genuine Samsung 40T’s being made now. Older 40T1 cells will not have “N40T”. They will have a zero as the second character of the first line of codes. The other characters in that first code line don’t matter to us.

Having “N40T” does not guarantee that it is a genuine 40T cell though! Codes can be faked. But if the code is not N40T for a cell claiming to be a Samsung 40T3 (or recently manufactured 40T1) then it is probably a fake.

THESE CODES CAN CHANGE AT ANY TIME!

I can only report what I know at the time but as soon as I can confirm that a code change is legitimate I will post about it.

The ratings in the 40T3 document I have are marked as tentative so I will use the 40T1 ratings for now. Samsung rates the 40T1 at 35A continuous and 45A if you do not let the cell reach 80°C (very hot). In my opinion this lets the cells get too hot to ensure decent cycle life so I am rating the 40T3 at 30A continuous and 40A if you do not let it reach 80°C. Both the 40T1 and 40T3 are best used at 25A and lower though. At above 25A or so the Samsung 30T is the better choice.

The 40T3 performed the same as the 40T1 at 10A but at above 15A or so the 40T1 is the better performer. But the 40T3 datasheet shows it having a much longer cycle life than the 40T1. So while Samsung increased the overall life of the 40T, something I am sure their customers wanted, you get nothing for free with li-ion cells and I guess the performance had to drop a little. The 40T3 datasheet shows the 40T3 equaling the 40T1 though.

The two cells I tested delivered 4162mAh and 4177mAh and had a DC internal resistance average of 12.9mOhm. This is good consistency and both cells exceed Samsung’s 4000mAh nominal capacity rating.

These cells were purchased for testing from 18650BatteryStore (www.18650batterystore.com).

Full Test report: https://bit.ly/3we1f2V

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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, Murata, LG, Panasonic, Molicel, 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 and you use them AT YOUR OWN RISK. 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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Excellent work, thank you Mooch!

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Dang too bad the price just skyrocketed on these cells. Craaaaazy

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Rumor has it that the manufacturers are having bidding wars for any available cells or that the prices are going up 10%-15% every couple of months (depending on the manufacturer and customers). :scream:

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Lol, yeah the slight size difference between these and the p42a makes for a huge pain in a certain build I am trying to put together.

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All samsung cells are hard to get now.

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What is the size difference?
I have a tight ss enclosure for my evo, and every mm. count.
And my builder is ordering these now, since p42a is mia, for who knows how long.

Fractions of a mm

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So i wont be feeling the same pain you did in april, i hope. :smiley:

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I just got this 50$ tool for doing accurate resistance measurements on cells but no surprise and depending on the slightest movement of the contacts the results are all over. I’m returning it

I was just going to test by measuring capacity using a hopefully accurate wattmeter and power supply.
If anyone has any advice.

Got this https://www.amazon.com/HTRC-Precision-Analyzer-Battery-Voltage/dp/B06XPVKY13

Will discharge down to lowest voltage in spec sheet then charge through the power supply and wattmeter.

21mm for the 40T vs 21.7mm for the P42A

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So, i’ll get more room with these. Sounds good.

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