Makita power tool batteries and charger

Not long ago, I was asked to test and review some batteries for Makita power tools. Since this is right up my alley, and the batteries were expected to be good, I thought, why not? In short and subjectively: they’re solid. For the long, objective version, read on.

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The original plan was to test just a pair of batteries, with the charger as payment for the work. But, to get ahead of myself, I liked the charger just as much as the batteries, so it’ll get its own review, complete with a teardown.

The package was quite substantial, and everything was packed very neatly: a box containing two boxes, one of which contained two more boxes, with the batteries inside, wrapped in bubble wrap. There are no manuals for the batteries, but I doubt anyone needs them.


As I mentioned, there were two batteries: 5 and 6 Ah, models BL1850 and BL1860, respectively. Today’s review is of the smaller one; the other is still being tested. The website also lists a 4 Ah BL1640, but in my opinion, it’s not a very interesting option in terms of size/capacity/price.


The batteries are sold under the TPcell brand. The case has a plastic label showing the capacity and voltage.


The connections are standard for a Makita tool battery, and I think many of you use batteries like this. Besides the power contacts, there’s also a communication terminal. It’s claimed to support original chargers, but unfortunately I can’t verify that at the moment.


There’s a charge indicator, but its implementation on this version is inconvenient: it only lights up while you hold the button. I’m more used to indicators that stay on for a few seconds after you release it.


The markings are on the bottom of the battery, also on a plastic label.


The battery weighs just under 600 grams.


The product page lists the protections built into these batteries. We’ll check them where possible, though that means taking the battery apart at the very least.


The screws have a hexalobular socket. I didn’t check the size; the smaller bit from my Hikvision camera screwdriver set fit.


The battery pack itself doesn’t rattle around, but it comes out of the case fairly easily.


The battery protection and monitoring board is assembled fairly neatly. Unfortunately, though, I couldn’t see any waterproof protective coating. The product page image shows coating on the transistors, but there’s none here. It’s not a deal-breaker for me personally—I can give it a couple of sprays from a can—but I’d still like the manufacturer to remember to coat the board.


1. Short-circuit protection fuses. If the overload protection fails for some reason, the transistor below is part of the overcharge protection circuit; to the right is some kind of controller.
2. Voltage regulator, current-sense shunts, and transistors for the overload and overdischarge protection circuits.
3, 4. Indicator board, built around four TL431s—simple and inexpensive.

I would have wrapped up the board review here, but then I noticed that overtemperature protection was listed, so naturally I went looking for it. I found the protection components under the board, along with another controller. I’d guess that this one handles overload/overtemperature protection and the like, while the one on top handles communication with the charger. So I’d expect it to work fine with genuine chargers too.
I wanted to remove the board, but the contact strips aren’t just soldered to it—they’re inserted through holes, bent over, and then soldered, which makes removing the board quite difficult.

Speaking of genuine batteries, lately I’ve been seeing complaints about Makita batteries getting locked out. People end up replacing the original board with boards from AliExpress. I should also note that the factory protection board has limited cell monitoring and lacks power components to protect against overdischarge.


I noticed damaged plastic on the battery holder at the end of the pack, which surprised me a little. It looks as though someone tried to check the markings on the cells. I assure you, it wasn't me, although it did make my job much easier.


The battery pack is built from ten INR18650-25P cells, and they are clearly genuine, as each has a unique serial number.


And yes, a quick search for the markings led me straight to EVE INR18650-25P. I recently reviewed other batteries from this manufacturer and was more than satisfied with them.
Their detailed datasheet is easy to find online. So at this point, I can already say that the test results are fairly predictable: at the very least, these aren't cheap cells, but proper high-current batteries from a reputable brand.


It's hard to check the strip material in this form, but it's nowhere near as thin as foil. The weld quality is also good.


Before testing, I quickly took some initial measurements, starting with voltage. There's a little variation, but I wouldn't call it significant. I should also note that the battery arrived charged, which suggests it had been checked for proper operation and possibly even balanced.


I measured the cell impedance after fully charging the battery, so the voltages differ from those in the previous photo.
The datasheet specifies:
Initial Internal Impedance is measured at AC 1kHz at shipping SOC.
Initial Internal Impedance ≤ 18mΩ

Since the cells are connected in parallel in pairs, the impedance should be no more than 9 mΩ per pair, or 45 mΩ for the whole pack. As you can see, the actual figures are closer to 7 mΩ per pair (14 mΩ per cell) and 35 mΩ for the whole pack. The total is slightly higher than the sum because it also includes the contact strips.
So far, so good.


The product page also includes capacity measurements for the cells, taken with a dedicated battery tester. According to those measurements, capacity is 4914 mAh. For some reason, though, the test current is an odd choice: 2 A is high for 0.2C and low for 0.5C.


Before taking measurements, I ran my usual conditioning cycle: first I fully charged the battery in the stock charger, then fully discharged it at 1C, and charged it again.
By the way, I used the supplied charger to charge the battery for all the tests, and noticed a minor quirk. If you simply insert the battery and charge it, the charger leaves it slightly undercharged. If you remove and reinsert the battery after charging is complete, it slightly overcharges it. This is absolutely not a problem in normal use, but it can introduce some error into the measurements.

The first discharge cycle yielded 4659 mAh, or 83.80 Wh.


Next, I took three measurements with the EBC-A10H electronic load, using currents of 0.2C, 0.5C, and 1C.
At a test current of 0.2C, capacity came to 4795 mAh, or 88.43 Wh. The tester was connected to the battery's external terminals, not directly to the cells.
Capacity was slightly lower in the subsequent tests, but not by much. The overdischarge protection cuts off at around 13.8–13.9 V, or 2.77 V per cell. That's perfectly normal and safe, since the manufacturer allows discharge down to 2.5 V.

Unfortunately, the battery still fell short of the 4914 mAh shown in the screenshot on the store page. I measured around 4800 mAh, or 2400 mAh per cell—about 55–60 mAh less.


I tested the load capacity only up to 30 A, since that's all the electronic load can handle. Even then, during the first cycle, the load's own overtemperature protection kicked in almost at the very end. The second run was on a partially discharged battery, so it went fine.
This test is relatively slow. Even during a single 0–30 A cycle, the battery managed to deliver about 30% of its capacity, so we can confidently say it handles 30 A just fine.


Next, I ran three measurement cycles, first at 10 and 15 A. The battery delivered almost the same result in both cases, around 4710 mAh.


Thermal images: 10 A on the left, 15 A on the right. I didn't take the case apart, but I was still able to measure the cell temperatures through the openings: 45 and 58 degrees, respectively.
The center image is just a general shot of the testing process :)


Test at a 20 A load current. I wanted to check continuous discharge at a higher current too, up to 30 A, but it turned out the load simply couldn't handle any more, since even at 20 A the power was 350–400 W.
I got about 4750 mAh here. I've been asked before how batteries can deliver more at a seemingly higher current, rather than less. It's very simple: the temperature is higher, so the output increases. Above a certain point, the capacity delivered in Ah can easily go up, while the capacity in Wh will still go down. So no laws of physics are being broken.


Temperature. In this case, the battery was partially disassembled: I removed the top cover so I could quickly take out the battery module and measure its temperature.
1. Circuit board. You can see significant heating around the battery's positive busbar connection and near the fuses. The transistors in the overload/overdischarge protection circuit are also heating up, for obvious reasons.
2, 3. The cells warmed up to 74 degrees, which I'd say is perfectly normal. They were running at 4C, but they were inside a closed case, assembled into a pack, and also heated by the current-carrying busbars.


The power circuit uses two pretty decent G017N04 transistors, each with an on-resistance of 1.7 mΩ, as well as two 3 mΩ shunts, giving a total of about 0.9 + 1.5 = 2.4 mΩ.
The total power dissipated in this section at 20 A was 0.0024 × 20 × 20 = 0.96 W, so 83 degrees in this spot is also perfectly normal.


The obvious question is: what can you do with 20 A? That doesn't seem like all that much, does it?
First, it's more than enough for any cordless screwdriver or drill, especially since they only run for short periods. And for short bursts, there are no problems at all.
Second, it can power an angle grinder or circular saw. They run for longer, but even then, the current rarely stays above 20 A for long.

For example, here's the current draw of an angle grinder with no load, powered at 21 and 18 V.


Under load, the current is usually around 20–25–30 A, but again, it's unlikely you'll be able to cut continuously for that long in practice.
Here's something I was cutting in one of my cordless angle grinder reviews, powering it from an adjustable power supply. The current periodically tried to exceed the 22 A limit, and the power supply went into current limiting, but it didn't stay there for long. In any case, the battery can deliver 500–550 W for about 5 minutes, and you can cut a lot in that time. After that, it's best to let it cool down a little.


And of course, I tried it in a tool—in this case, a “Makita-style” cordless screwdriver. The battery fit perfectly, with a crisp click from the latch and no rubbing at all. It just fit as if it had always been there.


Now for the conclusions, starting with the key part: the batteries themselves. This gets an emphatic thumbs-up from me. It doesn't just use batteries with decent capacity; they're branded cells, and genuinely high-current ones at that. The shortfall in capacity is easily explained by variations in the cells' own specifications. I've seen the same thing even with cells from top-tier manufacturers.
And of course, these cells are definitely better than no-name ones with 50% capacity, some generic “Litokala,” or, for example, the ones I reviewed before.

Now, a few words about how this kind of battery might be better than a branded one.
Protection: branded tools usually have three terminals and shut down when the battery signals an overdischarge or overload. Chinese tools designed for Makita batteries usually don't have a third contact, so they'll keep drawing power from the battery until you realize it's “all over.” Unfortunately, reviewers of this kind of tool often seem to "forget" about this feature.
Monitoring — I can't say for sure, since I haven't taken apart any genuine batteries, but I've repeatedly read that they don't monitor every cell in the pack. This can lead to voltage imbalance, and you won't know about it.
Lockout — again, I've repeatedly seen reports that genuine batteries can lock themselves out, much like laptop batteries, and unlocking them is quite difficult. So users simply replace the board with a Chinese one.

This battery has its own built-in protection, so it can be used with any tool, and it also monitors the individual cells. It presumably has a balancer, but I can't say that for certain. When I tried to inspect the underside of the board, I saw small transistors, but no high-power resistors nearby, and I didn't remove the board.

There are some drawbacks, too. For example, the listing claims the board has a protective coating, but in reality it doesn't. The charge indicator is also rather inconvenient.
Another drawback is the fairly expensive shipping: $10.5. Ordering several batteries of the same type works out a little cheaper, but if you order batteries with different capacities, the shipping costs are simply added together.

The seller later got back to me about the coating and said that my battery was deliberately left uncoated so I could inspect the board in detail. They assured me that the boards sold to customers are coated.

All in all, subjectively, I liked the battery; objectively, it's good too, though I do have a few reservations. It's worth buying.

That's all for now. Next up is a review of the 6 Ah battery. They claim it uses Samsung cells, so we'll see :)