Panasonic NCR18650BD Batteries: Tesla in Your Pocket

A new batch of batteries arrived not long ago, and today I’m reviewing the first one: the Panasonic NCR18650BD, with a claimed capacity of 3200 mAh.


I’ll start with a brief digression.
I received another package of batteries, and it will probably be the last one for a while. It’s the last because I’m not planning to order anything else for now. Also, my long saga of repairs is coming to an end, and I plan to get back to my stalled projects soon. I may also make a video about where I’ve been all this time, and why there have been so few reviews of electronic devices and so many battery reviews. I’ve already started assembling the device for testing battery packs that I talked about last year, but back then I had no idea it would take this long.

As before, I bought several types of batteries, two of each. This time, though, they didn’t come in a nice plastic box; they were simply wrapped in film. Still, everything was packed very securely, so special thanks to the Nkon store for making sure customers receive their goods in one piece.



The batteries in this batch aren’t all that common. There’s even one that’s quite rare. I also ordered a couple of new battery types made by Molicel. I haven’t seen any reviews of them yet, and people have been asking me about them.


But I’ll start with the almost run-of-the-mill Panasonic NCR18650BD. They’re neither high-capacity nor high-current batteries, but as far as I know, this type was used in Tesla car batteries.


I found two datasheets. A shortened version is shown below; the full one is available here.

As you can see, their capacity falls a little short of 3200 mAh. But there’s something more interesting: the datasheet gives figures for two charging modes, up to 4.2 V and 4.15 V. I won’t claim this as fact, but I’ll venture a guess that the second charging option is also used in those same Teslas. At least, I’ve come across this information more than once. This kind of limit extends battery life, but as the datasheet shows, less energy is stored as a result.


They look like ordinary Panasonic batteries. Probably the only noticeable difference from the common NCR18650B cells (including the "clones") is that these are gray rather than light green.
Judging by the 8X24 code, the batteries were made on October 24, 2018, which is pretty good, in my opinion.
I’ll also note that, unlike the batteries I tested before, these are marked as made in China.

A matrix code is visible under the heat-shrink wrap. It should be unique to each individual battery. I first saw it on Sony/Murata batteries, then on LG, and now on Panasonic. That’s a good thing, because this kind of code is harder to counterfeit, though it’s certainly possible.


Dimensions and weight are nothing out of the ordinary.


A "conditioning" run showed a capacity of 3400 mAh, with very little difference between the two cells. The discharge current was 500 mA.


Since the charger shown above tends to overstate the result, I’ll connect the batteries to an electronic load and test them more accurately. Their maximum discharge current is 10 A, so I’ll use the ZKE EBC-A10H load.


The recommended charging current for these batteries is 0.3C (910 mA). This is where an "quirk" of my load showed up: if the charging current falls within certain ranges, it can change during the process. This doesn’t happen during discharge. And other users of this load have reported the same "quirk".
But that doesn’t really change anything: a full charge takes more than four hours, so all the tests took a very long time.


The product description, the full datasheet, and other websites all mention a maximum discharge current of 10 A. However, the graphs in the shortened datasheet only go up to 2C.


I ran the tests across the full range, up to 10 A.
The graph includes these discharge rates: 0.2C (red), 0.5C (orange), 1C (yellow), 2C (green), and 10 A (light blue).

The first battery was tested with a charge termination voltage of 4.15 V, a charging current of 910 mA, and cutoff when the current dropped to 60 mA.
The result was a maximum of 3179 mAh or 11.51 Wh at a discharge current of 0.2C. At the maximum current, the result was not much lower: 3058 mAh or 9.98 Wh.


The manufacturer specifies continuous discharge at 10 A, with the caveat that the case temperature must not exceed 70 degrees. I didn't take the limit into account, but in this case it wasn't really necessary. In the open holder, the battery only slightly exceeded that threshold, heating up to 73 degrees.


I charged the second battery to 4.2 V before the tests, but the difference wasn't all that significant, in my opinion: at 0.2C, capacity was 3248 mAh or 11.8 Wh, and at the maximum current, 3143 mAh or 10.27 Wh.


But this battery had heated up more by the end of the test, reaching 76 degrees. The temperature rises very quickly toward the end of the discharge, and since the discharge itself took longer, the temperature went up as well.


And, of course, here's a comparison graph at 0.2C, 1C, and 10 A for the first and second batteries—or, more precisely, for charge voltages of 4.15 and 4.2 V.
The 4.15 V graph is shown in blue, and the 4.2 V graph in red.



And, as always, measurements of the internal resistance of the first and second batteries as received, after “conditioning,” and after all the tests.


After I'd finished writing the review, I thought it would be a good idea to compare this battery with another one. I remembered my recent review of the LG INR18650MH1, which has very similar specs: 3100 mAh capacity and a 10 A current rating. If you'd like to see other comparisons, let me know and I'll do them.


And now, the conclusions.
These batteries don't stand out for their high capacity or high discharge current. They sit somewhere between high-capacity cells and “medium-current” ones, like the LG HG2, but still have pretty good specs. In my opinion, they're an excellent choice for large e-bike battery packs in terms of capacity/size/price/reliability. For example, these batteries are more appealing than the INR18650MH1 shown above, since they cost less while offering comparable capacity.

That's all for now. As usual, I'll be glad to hear your questions and suggestions for future tests.