Here’s another cell review! This time it’s a Molicel/NPE, distributed by LiionWholesale. This is a high current (35A), middle capacity (3000mAh) 20700 lithium ion cell. Read on for testing!
As always, click for bigger images!!!
Here’s a link to the official Molicel product page at LiionWholesale. LiionWholesale is the official North American distributor of this brand!
These cells start at $7.69 for one or two, and volume discounts start with just 3 cells!
This cell meets its claim of 3000mAh. I can’t test over 20A, but the cell does seem to perform capably at 20A. There was a little bit of inconsistency between the high current testing results, but this could just be due to temperature variations in the room.
These ship in a 2-up plastic flip top package.
These are wrapped in the standard Molicel primer-grey wrapper. All the sizes of Molicel have this same wrapper. It could be a little confusing, but the size is printed right there on the side. Also printed on the side is a “+” and “-“, which is a nice touch.
The positive terminal is a five prong terminal, and flat top.
I’ve tried to keep the scales similar, so over time the charts will be generally comparable. I also spent probably 6 hours working on more automation for the spreadsheets I manage this data in (yes, I use Excel). Hopefully that 6 hours spent will cut hours off processing the data from future tests. To wit: I need more cells for testing!!
“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.
This is a fine cell. I don’t know many flashlights that use 20700 cells specifically (usually it’s either 18650 or 21700), but for flashlights this would likely be a very good for just about any flashlight.
- These cells were provided by LiionWholesale for review. I was not paid to write this review.
- This content originally appeared at zeroair.org. Please visit there for the best experience!
- Whether or not I have a coupon for these cells, I do have a bunch of coupons!! Have a look at my spreadsheet for those coupons. It’s possible to subscribe and get notifications when the sheet is edited!!