Another Vapcell for review! This is a mid capacity 18650 with high current capability – much like many of Vapcell’s cells… Vapcell has a bunch of cells!
As always, click for bigger images!!!
Looks like these are going for around $8.
These seem like good cells, but between my A and B cells there was some variation at high current. Otherwise, no complaints.
The zipper pouch for these cells has a cell-matching red trim!
I’ve tried to keep the scales similar, so over time the charts will be generally comparable.
Above you can see how the high current (15/20A) of the A cell didn’t perform as well as the B cell.
“Bounce back” is what the cell voltage does when the cell rests after a discharge. After heavy discharge rates, the cell voltage bounces back higher when discharge is stopped. This corresponds to a discharge amount of less energy, and does mean that there’s energy left in the cell. So if I selected the cell with the highest bounce back voltage (ie the cell that was discharged at the highest current), then discharged it to 2.8V at 0.2A, I’d still find that there was a lot of energy still in the cell.
Here is why I think it so interesting about “Bounce.” A poorly performing cell will bounce back higher after high discharges. That’s because the IR is higher, and because the cell performs much worse under high loads. So a good performing cell will bounce back much less because it’s much more capable of high discharge. At high discharge on a capable cell, more of the energy makes its way out of the cell! Hence less bounce.
I more or less figured this out on my own, so I welcome discourse about this topic. Until I hear it’s wrong, I propose this as a new metric for cell quality!
Most often (read: always), internal resistance is mentioned as a spot value. In truth, the IR changes over time. Due to cell age and cell heat among other things. A graph of IR is interesting because it can show, for example, when a cell begins to “die” – at which point the remaining energy will be “harder” to extract. This is when the IR spikes. In the graph below, that’s around 750-800mAh. These graphs are also useful for determining if a cell would be good for a hot-rod flashlight, for example.
Good capacity and pretty good current. My only complaint is that the A cell and B cell aren’t of the same quality.
- These cells were provided by Vapcell for review. I was not paid to write this review.
- This content originally appeared at zeroair.org. Please visit there for the best experience!
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