Imren Yellow 25A 3400mAh 18650 Bench Test Results...just a 12A battery

[Mooch]

These cells were purchased for the purposes of testing by me. To prevent any confusion with the eGo-type "batteries", I use the term "cell" here to refer to a single 18650, 26650, etc.


Disclaimer
The statements, 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 cells 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.


A note regarding current ratings and my testing
If the cell has only one current rating number on it, or if it says "max discharging current" then I have to assume that the company is stating that the cell can be discharged at that current level in any way, including continuously.




Bottom Line
This Imren is a 12A cell with a very exaggerated current rating. The capacity rating is exaggerated too. It's most likely a rewrap of a cooler running 10A battery but it doesn't physically match any cell I have tested. At only a 15A continuous discharge it's almost hot enough to boil water though. A continuous discharge at its 25A rating resulted in the cell delivering only about 40mAh down to 3.2V. Yes, that's right, 40mAh.


Continuous-Current Test Results



Pulsed-Current Test Results



Comments

• At 10A continuous it reached 63°C and about 2860mAh. This is about average for high internal resistance, high capacity 3200mAh cells at 10A so I am rating this cell at 3200mAh. It is possible that these cells are good performing LG MG1 rewraps but I haven't tested that cell yet.
• At 15A continuous the temperature rose to 96°C, almost to my safety limit of 100°C. This is way, way above the average temperature for a cell operating at its CDR, indicating that we are operating at significantly above the cell's actual rating. The voltage is low and sagging a lot.
• At 20A continuous the voltage sag was huge and the temperature rose to 116°C, significantly above my safety limit.
• At 25A, the cell's rating, the voltage plunged quickly to a useless level.
• I am setting a CDR of 12A for this cell. Operating at that level would bring the temperature of this cell up to the average of a cell operating at its CDR. While operating any cell near its rated maximum current level causes damage to the cell, I would expect decent cycle life from this cell at 12A continuous.
• I have included pulsed discharges but I haven't set pass/fail standards for pulse testing yet. The discharges were done at 5sec on/30sec off, down to 2.5V. One chart shows the entire discharge at each level. The other chart is zoomed in to show the first 5 minutes to make it easier to see the voltage sag at different current levels.

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
18350 Safety Grades and Pulse Performance Data | E-Cigarette Forum
18650 Battery Ratings -- Picking a Safe Battery to Vape With | E-Cigarette Forum
26650 Safety Grades and Pulse Performance Data | E-Cigarette Forum

 

[sonicbomb]

Battery purchase flowchart:

Is it a rewrap? → Don't buy it