Gpower Yellow/Black 25A 2600mAh 18650 Bench Test Results...a poor performing 19A 2500mAh battery

[Mooch]

The two cells tested were donated by Gpower (Gpower Battery- Gpower 18650 26650 li ion battery and battery charge wholesale) for the purposes of testing. Thank you! 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 tested out as a poor performing 19A 2500mAh cell. The 20A 2500mAh Samsung 25R delivers about 1300mAh at 20A down to 3.2V. The 20A 2600mAh Sony VTC5 delivers about 1250mAh. This Gpower only delivers about 750mAh. And that was only after two cycles at moderate current levels to "break it in", something that should never be required. When discharged at its 25A continuous rating it became almost hot enough to boil water.

This cell doesn't match the appearance or performance and of any Samsung, Sony, LG, Panasonic, or Sanyo battery I have seen. It appears to be a China-manufactured cell and not a rewrap. It has "ICR" on the wrap but I don't know which battery chemistry they're using. "ICR" is used for both the chemistry that is in LiPo's, lithium-cobalt (LCO), and for the "hybrid" chemistry that is in 25R's, HE2/4's, VTC's, and other batteries, nickel-manganese-cobalt (NMC).

While the cell does list the continuous current rating in very small print on the "back" of the wrap it has its useless "pulse" rating in huge print on the "front" of the wrap. I feel this is misleading and I encourage all battery companies that sell to the vaping community to only use the continuous current rating in large print or to use both, e.g., "25A/40A" for this cell.

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


Continuous-Current Test Results



Pulse-Current Test Results



Comments

• At 10A continuous it reached 2262mAh. This is poor performance for a 2600mAh cell at 10A so I am rating it at 2500mAh.
• At 15A continuous the temperature rose to 71°C. This is below the average temperature of a cell operating at its continuous discharge rating (CDR). This is an indication that we are operating below its true rating.
• At 20A continuous the temperature rose to 82°C, just above the average temperature of a cell operating at its CDR. This is an indication that we are operating very near its true rating.
• At 25A continuous the temperature rose to 98°C and the voltage sag is huge. This is an indication that we are operating at way above its true rating. This is clearly not a 25A cell.
• At 30A continuous the temperature rose to 111°C and the voltage sag was so severe that the cell is essentially useless.
• I am setting a CDR of 19A for this cell. While operating any cell near its rated maximum current level causes damage, I would expect ok cycle life at 19A continuous.

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
https://www.e-cigarette-forum.com/f...afety-grades-and-pulse-performance-data.7566/
https://www.e-cigarette-forum.com/f...des-picking-a-safe-battery-to-vape-with.7447/
https://www.e-cigarette-forum.com/f...fety-grades-and-pulse-performance-data.7554//