Efest 35A 2900mAh 18650 Bench Test Results...only a 15A+ battery

[Mooch]

Tested at 10A-35A constant current and 35A pulsed. These cells were purchased by me and used only for testing. To prevent any confusion with the eGo-type "batteries", I use the term "cell" here to refer to a single 18650, 26650, etc.

These are safety-oriented tests, not for performance. Though you can get a lot of performance information from them they are primarily done to check the manufacturer's/rewrapper's ratings and to establish safe continuous discharge limits.


Disclaimer
The conclusions and recommendations I make based on these tests are only my personal opinion. Carefully research any battery you are considering using before purchasing.

Testing batteries at their limits is dangerous and should never, ever, be attempted by anyone who has not thoroughly studied the dangers involved and how to minimize them. My safety precautions are the ones I have elected to take and you should not assume they will protect you if you attempt to do any testing. Do the research and create your own testing methods and safety precautions.




Bottom Line
In my opinion, this is a 15A continuous discharge current (CDR) cell with good capacity for its rating. At its 35A continuous rating the voltage instantly plummets and the cell quickly gets very, very hot.


Continuous-Current Test Results



Pulsed-Current Test Results
These pulsed-current tests are only done to show the performance of the cell at its pulse or maximum discharge rating. Do not set your coils or power levels to draw this much current!



Comments

• At 10A it reached about 2750mAh. This is good performance for a 2900mAh-rated cell at 10A. I am giving this cell a capacity rating of 2900mAh.
• At 15A the maximum temperature reached 73°C. This is 4°C below the average temperature of a cell operating at its CDR.
• At 20A the maximum temperature reached 86°C. This is 8°C above the average temperature of a cell operating at its CDR.
• At 25A the temperature rose to 102°C, exceeding my 100°C safety limit.
• A discharge at 30A was not done as it would have resulted in the cell temperature exceeding my 100°C safety limit.
• A discharge at 35A was done to show the performance of the cell at its 35A rating. The voltage dropped immediately to 3.4V and sank down quickly from there. The discharge had to be stopped early because the temperature rose above my 100°C safety limit.
• While five additional cycles at 20A only showed about the same amount of damage a cell being operated at its CDR for several cycles would show, but it runs too hot at 20A.
• I am setting a CDR of 15A+ for this cell. It runs a little cool at 15A but is too hot at 20A. It is most certainly not a 35A cell.
• A single pulsed-current discharge at 35A (4 secs on/30 secs off) was done to test the cell at its rating. The first pulse dropped the voltage down to about 3.3V. Its temperature rose to 60°C before the voltage eventually dropped to 2.50V.

To see how other cells have tested and how hard you can safely push them, check out these links:
List of Battery Tests | E-Cigarette Forum
18650 Safety Grades -- Picking a Safe Battery to Vape With | E-Cigarette Forum

 

[WharfRat1976]

At least it has the anti counterfeit label.

 

[Baditude]

At least it has the anti counterfeit label.

 

[WharfRat1976]

[emoji99]

Bad, do you get sarcasm bro?