Liionwholesale.com offers the Samsung 30Q Lithium-Ion Cell, which is my go-to high current 18650. These are reliable, and available!
That’s a pdf link. It includes all the important info, so I won’t paste it here.
These start at $4.73 at LiionWholesale.com, and there are volume discounts starting after 2 cells.
These are great cells. We knew that. But it’s nice to have data that confirms these cells from LiionWholesale.com are legit.
A set of 2 cells ship in the box above. Inside that 2-cell box are smaller single cell boxes. The cells are individually well isolated!
As expected these Samsung 30q cells have a bright pink wrapper. There’s a big white sticker with some specifications on the side of each cell – I don’t think this is a standard sticker but it’s still very common. (To wit: your 30q’s might not have this exact sticker – I think this sticker has to do with shipping regulations, and might be put on by different companies along the way.)
The wrapper has a white insulator above the positive terminal.
These are 18650 cells: 18mm in diameter, and 65mm in length.
Height : 64.85 ± 0.15mm
Diameter : 18.33 ± 0.07mm
Great cells for a brass TorchLAB BOSS!!
And below, see the two authentic 30q cells beside one fake 30q tagged with a LiitoKala sticker, from Aliexpress. Decently convincing, but differences can certainly be seen.
Particularly on the top of the cell – the authentic cells have a three prong terminal, and this fake 30q has a four prong terminal.
I’ve tried to keep the scales similar, so over time the charts will be generally comparable.
One thing about these tests is that this cell is only rated to 15A continuous! I tested it up to 20A, though. I did that with the fake 30q as well, so the charts are completely comparable.
Here’s a friendly reminder of the link to the fakies. There are a bunch of things you should look at – the voltage drop under high load. The much lower Bounce of the authentic cells. The consistency between cells (even under high discharge). Unfortunately I don’t have temperature data for the fake cells, though.
Please make a note of how absolutely consistent the A and B cells were!!
Sidenote, how do you all like the temp on the background of this chart?
Note that the max temp this cell is rated for is 75 degrees Celsius. Even under much higher than rated current (20A, vs a rating of 15A), the cell stayed within the temp specification (barely, but it did). (However, that’s not to say 20A is ok, or acceptable use case for these cells, but it’s nice to know that 15A isn’t a hard max, and the cells have headroom past that.)
“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 (like this one) will bounce back much less because it’s much more capable of high discharge. And we can see that here. 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, cell heat, and current capacity 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. These graphs are also useful for determining if a cell would be good for a hot-rod flashlight, for example.
The conclusion here isn’t that 30q cells are awesome. We already knew that! The conclusion here is that LiionWholesale sells authentic Samsung 30q cells.
Buy them here for $4.73 at LiionWholesale.com, but buy 4 or more to get them at $4.64 per cell!
- These cells were provided by LiionWholesale.com 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!!