BL1860 battery for Makita tools

So, I’ve just finished testing the second battery I received, and this one is the BL1860, rated at 6 Ah. Inspection, teardown, tests, conclusions—as usual.

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Since these batteries are mostly alike, the first part of this review will repeat the previous review, so anyone who has already read it can safely skip at least the first third.

Now, on to the description.
It came in the same kind of cardboard box. From the outside, it looks like a standard battery for Makita tools and compatible models.


There’s a capacity label on the side, now showing 6 Ah. Otherwise, everything is exactly the same, except it weighs about ten grams more.


Put it next to the previous one and the only difference is a single digit.


But there’s actually a more interesting difference: the charge indicator works the way I like it—press the button and it stays lit for a few seconds.


Since the cases are identical, the teardown process is exactly the same. Speaking of the case, it would be nice to compare its plastic with that of an original battery, but unfortunately I don’t have the opportunity.


This time, though, pink cells are visible at the side instead of green ones.


It uses the same circuit board as the BL1850, and unfortunately there’s no protective coating here either.


The contacts, system connector, and presumably the controller for communicating with the original chargers.


1. Power section: the same transistors, with an on-resistance of 1.7 mΩ. By the way, I forgot to mention last time that there’s an RC snubber across the transistors, which can improve circuit stability and reliability.
2. Overvoltage protection transistor for charging, and a pair of 30 A fuses.
3, 4. Charge-level indicator board. The circuit is naturally different from the previous one, and this one is also coated with lacquer on the underside (hooray, they found some lacquer :))


But let’s move on to the batteries.
The listing clearly stated that it uses Samsung INR18650-30Q cells. These are pretty good cells; I’d classify them as all-purpose, meaning they already have relatively high capacity while still delivering a decent current.


I have a review of these cells, bought from Nkon, so we can refer to the data I collected then.


The welds are decent, and the strips are fairly thick, just like last time.


While waiting for this battery, I wondered how they managed to use branded cells and still keep the price reasonable. There were several possibilities, including repacking. But when I took a close look at the welds, I figured out the trick: they used cells salvaged from battery packs. No, I don’t mean used cells, though I’ll check that indirectly too; I mean cells taken from new battery packs.


These cells are often sold by the well-known store Nkon. Here’s a quote from the product description:


I wouldn't say they're fully equivalent to new cells, since defective ones do turn up sometimes. But these are genuine cells, and if they've been tested before assembly, then yes, they're perfectly acceptable. Of course, I can't claim that the battery under review uses these exact cells; it's just that all my tests point to that conclusion.



And judging by the fact that the battery arrived charged, just like last time, I'd guess that they do test the cells after all. That's not certain, of course, but it's quite likely, especially since it's not difficult to do.


The typical impedance for these cells is 11–15 mΩ, or 5.5–7.5 mΩ when connected in parallel. In reality, we get about 6 mΩ, or 12 mΩ per cell—ideal.
Note that although I technically classify these cells as general-purpose, while the previous ones were clearly high-drain, their impedance is noticeably different: 35 mΩ total there, 30 mΩ here, which is of course very good.


As with the previous battery, the store page for this one also includes a capacity test result, though for some reason they measured it at 5 A. That doesn't really matter, though: the stated result is 5940 mAh, so that's what we'll use as our reference.


We fully charge the battery, connect it to the battery tester, set the current to 1C (I'm used to the standard values), and measure its capacity.
I got 5945 mAh at 6 A; the protection board cut it off. So far, so good: the difference between 5940 and 5945 is small, and in the positive direction.


The initial tests were performed with an EBC-A10H battery tester at 0.2C, 0.5C, and 1C, or 1.2, 3, and 6 A, respectively.
The results are right in line with the stated specs: 5933 mAh or 109 Wh.


For comparison, here are the test results for two brand-new, 100% genuine 30Q cells. Their capacity is about what you'd expect, and the difference is well within the measurement error.
But I was more concerned about something else: the characteristic shape of the discharge curve. You can, in principle, find cells with the same impedance and capacity, but matching the discharge curve as well...
In short, at this point everything suggests that these are brand-new, genuine 30Q cells.



By the way, the 30Q cell test also includes an impedance measurement, and the impedance there is actually a little higher than for the cells shown in today's review.


Anyway, let's try running the battery from 0 to 30 A. This went smoothly too; since it uses the same protection board, I wasn't expecting any surprises.


Next, a test at a discharge current of 2C, or 12 A. In my 30Q review, I got 2957–2963 mAh at 10 A, so we should expect around 5920 mAh here.
I got 5915 mAh, which is perfectly normal too.


As for the temperature, the battery heated up to around 53–54°C. The case was cooler, of course, but the thermal camera picked up something through the openings.


And now a test at 20 A, or 10 A per cell. Since this was going to be a longer test, I had to use a little trick to keep the load from overheating: I cooled it down first. That's why the temperature in the first photo is 13°C.

In the 30Q review, capacity at a 10 A discharge current was 2947–2956 mAh, or about 5900 mAh in a 2P configuration. I got 5868 mAh in this test, which is comparable, especially considering that I discharged the cells down to 2.5 V in that review, while here the cutoff is closer to 2.75–2.80 V per cell.


1. Board temperature
2, 3. Cell temperature was around 77°C, 3 degrees higher than with the previous battery. That's understandable: although the 30Q cells have lower impedance, the discharge took longer.


According to my own review of these cells, the case temperature at a 10 A discharge current was 56°C. Here it's nearly 77°C. Those extra degrees didn't come out of nowhere; two factors contributed:
1. This isn't a single cell; the cells are assembled into a battery pack, so they heat each other.
2. The battery is inside an unventilated case.

All of this puts limits on the continuous discharge current. I can't help thinking of a video I happened to see on YouTube. I absolutely don't want to troll or hate on anyone; I'm sharing this information only so you don't make the same mistakes.
In this video, someone showed a battery with some crazy cells (seriously, they're awful), but he also showed the NCR18650BD cells he'd bought as replacements. The seller told him they were high-current cells. What's more, the seller even replied to my comment under the video, but then stopped responding.
Although by the time I posted my comment the author had already rebuilt the battery with NCR18650BD cells, he did take the information on board and realize his mistake (I hope). The point was also that the author hadn't just brought in a single-row battery, but one from an angle grinder, too.

I once explained that high-capacity cells can be used in principle, but only in three-row battery packs. With a high overall discharge current, the current from each cell is three times lower.



Out of curiosity, I browsed OLX and found another listing, more expensive than the one the author bought, but its title explicitly says the cells are high-current.
How does that make any sense?


I didn't include this information for no reason. I reviewed NCR18650BD cells myself. They're decent cells with a genuinely specified maximum current of 10 A, but


But look at their temperature during discharge: 54 degrees at 6 A and 74 degrees at 10 A. Now imagine packing them into a small case and loading them at full current (let's assume the pack is 2P, with a total current of 20 A), and think about how hot they'll get.
The problem is compounded by the fact that high-current cells are more delicate, so to speak. In other words, the heat high-current cells can withstand is more damaging to high-capacity cells.
So, to repeat: single-row battery packs need genuinely high-current cells, such as the Samsung 20S or the new 25S model. Even the cells used in the battery under review are only suitable for 2P packs.



That wraps up the battery review, but I'd like to return to my review of the BL1860 battery. Today, just out of curiosity, I decided to run a small experiment. First, I ran a balancing cycle on all the cells to bring them to the same state. It turned out they were already reasonably well balanced. The charge added on the second charge was, in mAh:
182
179
191
164
161

So the largest difference was 30 mAh, and that was after a test cycle. I didn't check what it was before that.


After that, I fully charged the battery with the stock charger and discharged it at 1C while measuring its capacity. It would have been more accurate to discharge it at 0.2C, of course, but I couldn't be bothered to wait.
I got 4809 mAh, and I'm afraid that's really the maximum for this battery (I'm referring to the BL1850).


Later, I ran a balancing cycle on the cells. I can say that they weren't too bad to begin with—in fact, I'd even say they were good. The largest difference was 22 mAh, which is less than 0.4%. It's also clear that the biggest difference is between the fourth and fifth cells, which matches the voltage difference I measured at the very beginning.


And now for the conclusions.
In my opinion, this is a perfectly decent battery. It uses cells in the same class as the well-known VTC6, and personally, I think they're better than the LG-HG2 (not the LitoKala ones, obviously). The cells used are presumably genuinely new; the capacity and impedance measurements support that.
Objectively, the only thing I can fault is the missing promised protective lacquer coating. Subjectively, I would have liked to see a balancer, too.
The seller later explained that the battery had deliberately been sent without lacquer so the board could be shown in more detail.

I don't know what will happen down the line; this information reflects the situation at the time of writing. So far, I'm genuinely pleased with the results, and I hope the manufacturer doesn't start cutting corners. In practice, this particular battery is every bit as good as the genuine one, which, incidentally, uses VTC6 cells. And given that it has built-in over-discharge protection and no battery lockout function, it may even be better.
By the way, can anyone say for sure whether the genuine Makita battery has individual cell monitoring? I often see people say it doesn't, but in photos I can see wires connected to the cells.

Overall, I can say that I definitely like the battery under review more than the previous one, even though it's more expensive and the cells show signs of spot welding. No, EVE cells are good too, but personally I think Samsung is better. They also have 20% more capacity at the same discharge characteristics and weight.

Some people will say, “I'll just buy a genuine battery, rebuild it with LitoKala ‘HG2’ cells, and it'll be great.” No, it won't. First of all, even Liitokala cells aren't lying around free on the street: 10 of them will cost about $21–22. Second, I've already shown that even at 10 A they heat up to 73 degrees. Third, this doesn't solve the problem with the protection board.

That's all for today. I hope you found this information useful. I'll get started on a review of the charger now.