Bench Re-Retest Results: Samsung 40T 35A 4000mAh 21700...amazing performer but 25A/35A

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 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.




Bottom Line
This is another retest to check on the performance of this cell as it, hopefully, comes into full production soon.

This cell outperforms every 18650 and 20700 in regulated devices at up to about 20A-25A (60W-75W). Only the Samsung 30T hits harder for 21700’s. In my opinion though it is not a 35A battery, as rated in the datasheet.

At 35A continuous this cell reaches almost 90°C. That is too hot to ensure decent cycle life. A rating of 25A continuous brings it to about the same temperature that the Samsung 30T reaches at its rating.

At above 20A-25A (60W-75W) the Samsung 30T is the better performer anyway. The 40T is best at low to mid power levels where it can be the most efficient. The 40T is still an amazing 25A battery though!

If you are running your mod at 60W-75W per battery you will have to try both the 30T and 40T to see which performs better for the way you vape. It’s just not possible to predict.

The two cells I tested delivered 4048mAh and 4062mAh at 0.8A (0.2C) down to 2.5V.

I am estimating this cell’s ratings to be 25A with a temperature-limited rating of 35A (if kept below 80°C) and 4000mAh.

Two cells were donated for the purposes of testing by Fogstar (Fogstar - The UK's #1 trusted source of 18650 Batteries). Thank you!


Continuous Current Discharge Graphs



Ratings Graphic



Performance Specs
- DC Internal Resistance = 13.5mOhms (milliohms) average for the two cells.
- Total energy delivered down to 3.2V at 10A continuous = 11.3Wh (Watt-hours) average
- Total energy delivered down to 3.2V at 20A continuous = 10.1Wh (Watt-hours) average

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