AOSO 40A 2500mAh 18650 Bench Test Results...wildly overrated, only a 20A battery

[Mooch]

These cells were purchased by me for the purposes of testing. To prevent any confusion with the eGo-type "batteries", I use the term "cell" here to refer to a single 18350, 18650, 26650, etc.

While the test results are hard data, the conclusions and recommendations I make based on these tests are only my personal opinion based on my criteria for setting a rating. Carefully research any cell 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.

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 is just a wildly overrated 20A cell with a 2500mAh capacity rating. At 30A continuous, which is 10A below its rating, it gets hot enough to boil water. At 40A continuous it only delivers about 40mAh down to 3.2V. It looks and performs like the LG HE4.

The 18650 ratings table has been updated to include this cell.


Continuous-Current Test Results



Pulsed-Current Test Results



Comments

• At 10A continuous it reached about 2325mAh. This is about average for a 2500mAh cell at 10A so I am rating this cell at 2500mAh.
• At 15A continuous the temperature rose to 69°C. This is below the average temperature of a cell running at its continuous discharge rating (CDR).
• At 20A continuous the temperature rose to 79°C. This is the average temperature of a cell running at its CDR and an indication that we are at the cell's true rating.
• At 25A continuous the temperature rose to 90°C. This is a ridiculously high temperature and an indication that we are significantly above the cell's true rating.
• At 30A and 35A continuous the temperature rose to 102°C and 205°C, respectively. This is above my 100°C safety limit and is approaching dangerous levels.
• At 40A, the cell's rating, the voltage quickly plummets. This cell only delivers about 40mAh at its rating when discharged down to 3.2V.
• I am setting a CDR of 20A for this cell. 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 20A 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
18350/18500 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