Vapcell S4 plus four-bay charger with charging current up to 3 A per slot

Those who read my battery reviews have probably noticed that almost none of my tests go by without a "conditioning" cycle, which I run using a relatively simple charger. I reviewed it more than 5 years ago, and it served me faithfully all that time. But I think it's time to replace it with something more convenient and powerful, so today I'll be talking about the Vapcell S4 plus charger.


Let me start by explaining why "conditioning" is in quotation marks. I'm skeptical about the idea of "breaking in" lithium batteries, so to me this cycle is really just a preparation step, and it also lets me quickly check the capacity.
For many years, I've run this cycle using a relatively simple, yet perfectly capable charger. What makes it "capable" is that it can measure capacity during discharge, at either 250 or 500 mA (depending on the selected charging current). I'll come back to a "face-to-face" comparison a little later.

Anyway, this charger was starting to "wear out": the springs weren't what they used to be, the contacts had gotten a bit worse, and the display had become a little dimmer. Then I was offered the chance to try a charger from Vapcell, so why would I turn that down? There's already a review of it online, and it's so detailed that I doubt I could match it—and I don't see the point in trying.
Of course, there will be tests—what review would be complete without them? But what mattered to me personally was real-world use for genuinely practical tasks. That's why this review is coming out now, rather than two months ago when I received it. You may also have seen it in some of my recent battery reviews, but let's get on with the review.

I received it along with some batteries, which have now been tested and shown here. The box is large and includes all the necessary information about the charger's specifications and operating modes.


Everything is simply packed inside, without any foam inserts or anything like that.
The package is very straightforward:
1. Charger
2. Manual
3. Power supply.

Note that there's also a version without the power supply, which costs 6 dollars less. But in my opinion, with such a small price difference, it makes sense to get the complete package.


The manual is in English and includes the specifications, operating modes, and settings.
The power supply looks well made, and in use it proved to be stable. It outputs 12 V at up to 5 A, and judging by the charger's specifications, it uses almost all of that power.
The plug has no ground connection. The barrel connector for the charger is 5.5/2.1, not 5.5/2.5 as you might expect with this kind of load current.


Before getting into the details, here are a few useful links: the manufacturer's website, which also links to a full review in English, and the lacrosse-nn website, with a description in Russian. Since the device was provided directly by the manufacturer, I don't think I'm doing anything wrong by including these links in addition to the official store link.

Description
Four fully independent battery charging channels
•Supports Li-ion 4.2V (IMR/INR/ICR), Ni-MH, and Ni-Cd batteries
•Accepts batteries up to 75 mm long (including with a protection circuit)
•Supports low-capacity batteries
•Li-ion battery charging method: constant-current (CC) and constant-voltage (CV) charging
•Automatically detects charge completion by voltage drop (-dV) for Ni-Cd / Ni-MH batteries
•Automatic and manual operating modes
•Automatically sets the optimal charging current based on an analysis of the batteries' internal resistance
•Fast charging for Li-ion / IMR batteries (up to 3 A per channel)
•Adjustable charging current:
Li-ion: 0.25 A / 0.5 A / 1.0 A / 1.5 A / 2.0 A / 2.5 A / 3.0 A
Ni-Cd / Ni-MH: 0.25 A / 0.5 A / 1.0 A
•Adjustable discharge current: 0.25 A / 0.5 A / 1.0 A (1 A in slots 1 and 4)
•DISCHARGE mode to eliminate the "memory effect" and measure remaining capacity
•TEST mode to measure actual capacity
•RECOVERY/REPAIR mode to raise the voltage of over-discharged Li-ion batteries and restore the capacity of Ni-Cd / Ni-MH batteries
•Measures battery internal resistance
•Activates protected Li-ion batteries
•Display with switchable backlight
•Displays battery type, charging time, charging current, capacity, voltage, internal resistance, charge percentage, and battery temperature

Device specifications
Input: 12 V DC, 5 A
Charging current range: 250–3000 mA
Discharge current range: 250–1000 mA
Device weight: 330 g
Device dimensions (L × W × H): 115 × 170 × 40 mm

It looks much like other charger models, such as the Opus, four of which I used while preparing another review, so I can compare this charger with those as well.


And here it is compared with the charger I use most often, which has handled almost all the batteries I've tested.
It can also measure capacity during discharge, but it's called the 4S, not the S4 like the one under review, and it's clearly smaller.


Each slot has a temperature sensor to measure the cell temperature. This is a somewhat questionable design choice, since it's quite difficult to ensure good thermal contact under these conditions. Also, the sensor is partially warmed by the charger's own electronics, especially when the outermost batteries are discharging.


At first glance, it looks like you could fit four 26650 cells, but you can't—I checked. The most you can fit is a 26650 in each outer slot and two 21700s in the middle. The specs say it supports protected 21700s by length. Since there's still room after inserting unprotected 21700s, I believe that. My old charger could take either protected 18650s or unprotected 21700s.
The spring holds cells securely whether they're short 35 mm cells or 70 mm ones. Unfortunately, short batteries don't sit as securely in my old charger.


Below the display are three buttons for controlling the operating modes:
MODE button
Press and hold MODE for 2 seconds to change the operating mode of the selected slot. Press MODE repeatedly to cycle through Charge, Discharge, Cap test, and Repair modes. To change the mode for the next slot, press DISPLAY.
DISPLAY button
Used to select a slot. The parameters shown on the display apply to one battery. Press DISPLAY repeatedly to select the desired slot, CH1–CH4, and show the readings for that battery.
CURRENT button
In Manual mode, you can select the charging/discharging current yourself.
Within the first 6 seconds after inserting a battery, press CURRENT to select the desired charging current. Once the initial setting is confirmed, the current cannot be changed in Manual mode. To change it, press and hold MODE, then use CURRENT to select the desired current.

It's all very straightforward, except for one small detail—or maybe three:
1. My old charger had a single button. A short press changed the charging/discharging current (500/250 mA or 500/1000 mA), while a long press switched between Charge and capacity measurement modes. If the backlight had gone out, the first short press turned it back on.
2. There was no way to select individual slots; the mode was set for all four slots at once.
3. Changing the charging current doesn't reset the mAh/Wh counter, but here it does, which is inconvenient.
Very simple and convenient. Here, though, the user gets to choose how each slot is used. For example, you can set one slot to charge, another to charge, and a third to measure capacity. But in practice, that's rarely needed, so I think a combined-control mode, selected with a switch, for example, would be a useful addition.

There's also a Manual/Automatic mode switch on the side.
In Auto mode, the device analyzes the battery's internal resistance and automatically sets the optimal charging and discharging parameters. If you want to change the current, press and hold the CURRENT button, then select the desired value.
The following preset charging currents are available:
Li-ion charging current: 0.25 A / 0.5 A / 1.0 A / 1.5 A / 2.0 A / 2.5 A / 3.0 A
Ni-Cd / Ni-MH: 0.25 A / 0.5 A / 1.0 A
Discharge current: 0.25 A / 0.5 A / 1.0 A (1 A in slots 1 and 4)

As you can see, Auto mode actually lets you select the settings manually, too. By default, when power is applied, charging mode starts, and the charging current depends on the operating mode and the battery parameters.


The display is clearly specialized, i.e. designed for a specific device with a specific set of functions. With all segments lit, you can see that the device only supports nickel and lithium-ion batteries; neither high-voltage lithium batteries nor LiFePO4 are supported. While the former isn't a big deal (at least for me), I think the lack of LiFePO4 support is a major omission. Perhaps they left it out because the battery type can't be selected automatically, and they decided not to include it for safety reasons, although I think this mode is needed.

After the initial startup, the device measures the batteries' internal resistance and, if Auto mode is selected, sets the charging current. By the way, in one of the operating modes, with a high-capacity battery with high internal resistance installed, I couldn't force the charging current to its maximum value.

The blue backlight is even. The description says:
The display backlight turns on when any button is pressed and switches off automatically after 25 seconds. Charger operating modes

In reality, that's not quite how it works: the backlight stays on while the device is operating and turns off when all the batteries have been charged, discharged, or tested—in other words, when all cycles in all slots are complete. If you then press any button (I usually press Display), the backlight turns on, but doesn't switch off again...

The display has a fairly limited vertical viewing angle. More precisely, the lower edge of the window partially covers the bottom of the display, so it's easier to read from above than from the front.


If no batteries are installed, the display shows Null. Otherwise, it shows all the information you need about the current operation.


The power input and USB port are on the opposite side of the case.


There are several ventilation slots on the sides, and I can tell you they're definitely needed here.


There are four rubber feet on the bottom, along with another label listing all the device's specifications. So even if you lose both the box and the manual, you'll still know what it can do.


The device has a USB port and can be used as a power bank, with any number of slots in use. The output activates automatically when a load is connected; if there's no load, it switches to standby after a few seconds. While operating, the screen shows the batteries' charge percentage. It also has over-discharge protection: the port shuts off if the battery voltage drops to 3 V.
It would be great if not for the fact that the maximum output current is only 1 A, and the list of supported charging protocols is very limited. Still, the feature is there, and it works.


The USB output only works when powered by batteries, and only lithium batteries at that—though they can be any capacity or size. It switches off when external power is connected.


Naturally, I completely disassembled the charger and inspected it carefully, partly out of curiosity and partly to see what I'd be using for my upcoming battery reviews. Above, I mentioned that there’s a good review by a well-known author, but what I felt was missing from it was a teardown.
To take it apart, you need to remove six screws from the bottom. Four of them are hidden under the rubber feet.


The overall build quality is quite good; at least, I didn’t notice any obvious flaws.


Next to each slot, you can see pairs of diodes that isolate the slots when the USB output converter is operating. The converter chip is above them.


The converter uses an FP6276 chip, rated for up to 5 A and featuring synchronous rectification. That’s clearly overkill for the specified 1 A output.


This side also has 0.3 Ω current-sense resistors: one for each of the middle slots and two for each of the outer slots, where the maximum discharge current is twice as high. The controller is here too, along with the MOSFETs that control charging and protect against reverse polarity.


The controller’s markings have been rubbed off. Next to it is an HCF4051, an eight-channel analog multiplexer. It’s probably in the measurement circuit to save the microcontroller’s ADC inputs.
Nearby are packages marked TC4953 and 9926A. The first is a pair of P-channel MOSFETs, and the second is a similar pair of N-channel MOSFETs.


To remove the board, you first have to unhook the springs somehow. And I can tell you, it’s not as easy as it might seem.
Once the main board is out, you can see another board inside, connected to it by a flat ribbon cable.
The additional board has a pair of LCD controller chips, whose markings have also been rubbed off.
The plastic housing has special channels filled with thermal paste. They lead to metal plates next to the battery’s positive terminal and transfer heat to the temperature sensors.


The back of the main board holds the charging converters, as well as transistors that dissipate heat during discharge. You can also see steel guides that reduce the resistance of the negative sliding contact.


I couldn’t identify the DC-DC converter chips. There are four of them, with four inductors next to them, and this part of the board is partly covered with something like glue.
Above them is a pair of 30N06 transistors that handle discharge in the middle slots.


There are four temperature sensors next to the positive terminals. As far as I can tell, they touch the metal plates shown at the very beginning of the review.


The power connector looks well made. Next to it are the USB socket and the converter’s inductor. There’s also a pair of power transistors on heatsinks at the edges; they’re used to discharge batteries in the outer slots.

As I mentioned above, the maximum discharge current is 500 mA in the middle slots and 1 A in the outer ones. That means the maximum power dissipation ranges from 12.6 W at the start to 7.8 W just before cutoff, averaging around 10–11 W. The transistors don’t dissipate all of that power, though: some of it is dissipated by the current-sense resistors and protection transistors. Even so, the power transistors shown here have a pretty tough job. For example, a TO-220 package can dissipate up to 1 W without a heatsink, while these are handling around 1.5–1.6 W. Still, the charger worked perfectly normally while I was using it. Also, unlike my old charger, the transistors here are spread across different parts of the housing, so the heat is distributed more evenly and there are fewer hot spots. Yes, my charger has been working this way for several years, but the transistors are still operating under a very heavy thermal load.


At first, I planned to run various measurement tests, but then I thought it would probably be better to show the charger in action.
First, let’s look at how the automatic mode works—specifically, how it decides what charging current to use. It bases its analysis on the battery’s internal resistance: the higher the resistance, the lower the charging current. For example, at 40–60 mΩ, the current was 1.5 A; at 150 mΩ, it was just 250 mA; and at 25–30 mΩ, it had no trouble setting 2.5 A. I don’t think I ever saw the maximum 3 A, although I tried a fairly high-current Samsung 20S, which has low internal resistance.



Once all operations are complete, the charger turns off the backlight, but the display is still visible, especially when lit by a camera flash.


Capacity measurement. Basically, everything is great, except for one small but annoying detail.
In manual mode, I set the charging current to 3 A. The device set the discharge current to 1 A by itself, which is all good. It discharged the battery, but then charged it at 250 mA. I have to say, this is a really big problem, since charging a 5 Ah battery takes more than 20 hours! Yes, I recently posted several reviews of VapCell batteries, and tested them with this charger. As far as I can remember, in at least 17 out of 18 cases, charging also took place at 250 mA. I'm not sure about one test, as I think it may have been 500 mA. I later found out that charging takes place at 500 mA when "Auto" mode is selected.
The full test looks like this: charge at 3 A (set manually), pause for 2 minutes, discharge at 1 A (as I understand it, the slot's maximum current is used) down to 2.6 V, charge at 150 mA up to 2.9 V, charge at 250 mA up to 4.2 V, then terminate charging when the current drops to 100 mA.
The photo at the bottom right shows the end of the test: the battery is fully charged, and the measured capacity at 1 A (0.5C) is 1937 mAh (I got 2013 mAh in the review).


Testing NiMH batteries, and checking the recovery mode along the way.
For the test, I used batteries that had seen better days and were about 18–20 years old, with a capacity of 1800 mAh. As you can see in the photo, one of them had even started leaking.
I set the charger to recovery mode, but the first slot showed an error; that was the slot with the leaking battery. I took it out, cleaned the contacts a little, put it back in, and charging proceeded without any problems.
After two cycles, the charger had given them a bit of a boost, but there is one small catch: at the end of the test, it shows the capacity put into the battery during charging, not the capacity delivered during discharge.


You can see that the third slot shows a slightly odd capacity. This was the only time the charger failed to correctly detect the end of charging based on the voltage delta, and stopped charging for some other reason. The batteries were barely warm, so I won't hold that against it, especially since all the tests after that went perfectly.



I checked that charging termination was working correctly alongside the capacity tests. This mode was also more convenient for "reviving" the batteries.
In total, I ran 5 full charge/discharge cycles on four batteries, for 20 tests altogether. All the tests went perfectly, but the capacity stopped increasing very quickly. In the end, I got about 1200 mAh out of the original rated 1800 mAh, which is pretty good after all these years. The batteries had simply been sitting in a desk drawer for the last 5–6 years.


But in my opinion, testing lithium-ion batteries is more relevant, and I found these tests more interesting.
I used four Sony VTC4 cells, which I also reviewed a few years ago.


I fully charged the batteries and then discharged them at the maximum currents: 1 A for the outer slots and 0.5 A for the middle ones.


According to the charger's sensors, the two outer test batteries reached 61–62 degrees. The temperature was the same both one hour and two hours after the test began, so thermal equilibrium had been reached.


I should also mention that the state-of-charge percentage reading isn't entirely accurate. You could see that above, but not as clearly as here. The photo on the right shows 41% charge, but the battery is actually almost discharged.

There is clearly a relationship between the percentage and the cell voltage, but the discharge curve isn't taken into account, since voltage usually doesn't drop in a perfectly linear fashion.
So we get this:
At an actual 65%, it shows 83
At an actual 3–4%, it shows 24–25

Since the voltage drops very quickly after that, the displayed charge percentage also drops quickly. It reaches 0% at 2.6 V.


I monitored the temperature during discharge and got three readings: one hour after the test began, two hours in (when the outer batteries finished discharging), and three and a half hours in (when the middle batteries finished discharging).
Surprisingly, although the batteries got quite warm, the temperature didn't reach what I consider the critical level of 60 degrees. Given that cooling is passive, I expected them to get hotter.
Also, the temperature was almost the same after one hour as it was after two, so tests with higher-capacity batteries should be much the same.


End of the test. Here's another small observation: the voltage shown at the end of charging or discharging is the voltage at the moment the battery is disconnected. The voltage isn't monitored after that.
Results:
1. 1935 mAh, 6.96 Wh
2. 1902 mAh, 6.83 Wh
3. 1754 mAh, 6.22 Wh
4. 1800 mAh 6.42 Wh

I was surprised by how much the batteries' capacities varied, given that they were all manufactured on the same date and had generally been used in the same way.


Of course, I'll measure the actual charging and discharging current, but comparing the capacity measurements with my main tester, the EBC-A10H, will be much more informative.
The thing is, simple chargers—whether Opus, LiitoKala, or my old one—usually overstate the result. This isn't just because they're poorly calibrated (as people often assume), but also because batteries deliver more as their temperature rises above room temperature.

But here I ran into something odd: the results weren't very different. I tested batteries 1 and 3, from the first and third slots, respectively.
The results:
1. 1935 mAh 6.96 Wh (VapCell) and 1938 mAh 7.108 Wh (EBC)
3. 1754 mAh 6.22 Wh (VapCell) and 1746 mAh 6.471 Wh (EBC).

Honestly, I was a little surprised that the measured capacity in Ah was practically identical to the reading from my main tester. The Wh measurements differed, but that's to be expected with a two-wire connection: the EBC-A10H accounts for the voltage drop across the contacts, while the VapCell doesn't.
In both cases, the batteries were charged with the VapCell and discharged down to 2.6 V at the same currents (1 A for the first and 0.5 A for the third).


Now for a charging cycle.
Starting with fully discharged batteries, the charger set the current to 2–2.5 A, depending on the resistance. There's a “catch” here too: resistance is measured using DC, so it will be higher with fully discharged batteries. In automatic mode, the charging current may therefore be lower than if you set it manually or charge batteries that are at least 20–30% charged.
In this mode, the charger initially drew about 20–25 W, but after 5–7 seconds the power rose to 40 W because of the soft-start feature.
That didn't work for me, so I had to switch to manual mode and set the maximum current: 3 A per slot.
Power now reached 70 W (not counting power supply losses), so the charger itself was drawing about 60 W.


Before charging switched to the CV phase, I measured the temperature: it was 72 degrees near the DC-DC converters. The batteries were at about 50–53 degrees, while the power supply casing had warmed to just 47 degrees. The thermal image shows that the heat was concentrated around the typical location of the output diode assemblies.


A few measurements.
Voltage accuracy during charging, tested at the maximum current of 3 A.
Across the entire voltage range, from the start of charging almost to the very end, the actual battery voltage was 70 mV lower than the charger's display. The readings only started to converge as the charging current dropped, when the voltage was 4.2 V.
The fourth channel stopped charging at 4.1939 V. My old charger went up to 4.22–4.23 V.


Discharging cycle.
I could just about explain the voltage difference during charging by, say, the voltage drop across the contacts and circuit board traces. But I still can't figure out where the difference during discharge comes from.
The thing is, during charging, the battery voltage was slightly lower than the charger's reading. But during the charging cycle, the measurement error was in the same direction, which makes no sense. On top of that, the error was larger, even though the discharge current was three times lower than the charging current.

In short, I got a difference of about 120–130 mV between the actual and displayed voltage. Also, until the voltage at the battery terminals dropped to 4.07 V, the charger kept displaying 4.20 V. It seemed to me like a software offset—that is, a fixed value was simply being added to the actual voltage. I can't explain it any other way for now, especially since the difference between the actual and displayed voltage was the same at both 3 V and 4.2 V.


Discharging stopped at an actual voltage of 2.5006 V, while the charger displayed 2.53 V. As far as I know, the specified cutoff is 2.6 V. But this isn't critical here, since the discharge curve usually drops sharply at this point.


Charging and discharging current.
Since a multimeter was connected in series with the battery, the resistance increased, and the highest charging current I could set was 2 A. When I tried to set it higher, charging still took place at 2 A—a sort of protection against trying to charge “weak” batteries at high currents.

1, 2. Current fluctuated in all modes. For example, at a charging current of 500 mA, the actual current ranged from 480 to 510 mA.
3, 4. In the 1 A and 2 A modes, the actual current was lower than the set value, especially at 2 A.
5, 6. During discharge, the current was more stable, although it was slightly lower than it should be.


The other channels behaved almost the same; for example, we can compare them with the first one.
1. Charging current: 500 mA; the difference between the actual and displayed voltage was 15–20 mV
2–4. At a current of 3 A, the difference was 60 mV; at the end of charging, the voltage was 4.1955 V.
5, 6. During discharge, the difference was in the same direction as during charging and was the same 120–140 mV as on the fourth channel, which again points to some kind of software “correction.”


Discharge ended at 2.5086 V; the charger display showed 2.53 V, just as it did for the fourth channel.


Charging and discharging were also roughly similar to the fourth channel.


Oscillograms. For this, I had to put a 100 mΩ resistor in series with the battery to serve as a current-sense shunt, and connect the oscilloscope across it.
I chose 100 mΩ as a compromise: it makes the current easier to assess while having relatively little effect on the circuit.

Interestingly, the charger showed a resistance of just 71 mΩ, not 22–32 mΩ plus the shunt resistance—that is, 122–132 mΩ. After the battery had charged a little, it showed just 64 mΩ. I’ve written before that all these measurements made with simple chargers are very approximate, and this example confirms it.


Power-on.
When a battery is inserted, the charger first measures its internal resistance. It does this at 0.5 A, then pauses and switches to charging mode. In manual mode, the charging current is always 0.5 A; in automatic mode, it depends on the battery’s resistance. For example, the oscillogram on the left was captured in manual mode, and the one on the right in automatic mode.
Internal resistance is measured only once, when the battery is inserted.


Charging.
Below are four oscillograms captured at currents of 0.5, 1, 2, and 3 A. To capture one at the maximum current, I had to trick the charger a little: I shorted the shunt, inserted the battery, and let the charger measure its internal resistance. It then allowed me to set the charging current to 3 A. With the current-sense shunt in place, I could get only 2 A maximum.
As you can see, things look pretty good here: current ripple is not very high, which indicates proper regulation.


Discharging.
Here, though, the picture is less clear—I’d even say unimpressive. The reason is that discharge does not use CC mode; it uses a pulsed mode. In other words, the discharge current exceeds the set value, but is intermittent.
1, 2. Current: 250 mA. I took two screenshots specifically to show the “wobble.” It’s present in the other modes too, but is a little less pronounced.
3. Current: 500 mA
4. Current: 1 A

In practice, I found that at an average current of 250 mA, the battery discharges in pulses of 1.3–2 A. At 0.5 A, the pulses are already around 3.2 A, and at 1 A they reach 5.2 A.

Now, why is this bad? I’ve mentioned internal resistance several times in this review. It doesn’t respond well to pulsed rather than linear operation, because this causes the battery to heat up more and increases the overall load on it. Let me explain.
For example, take a 100 mΩ resistor. With 1 A flowing through it, the voltage drop will be 0.1 V and the power dissipated will be 0.1 W.
If the current is 5 A but flows for one-fifth as long (so the average is still 1 A), the voltage drop across the resistor will be 0.5 V and the power will be 2.5 W. But since the current flows for five times less time, the average power is 2.5/5 = 0.5 W.

So, with the same average current of 1 A, the first case dissipates 0.1 W, while the second dissipates 0.5 W. Of course, this depends heavily on the internal resistance, but either way it introduces measurement error and puts extra strain on the battery.

Unfortunately, many similar chargers suffer from this drawback. I think it’s done deliberately to reduce the thermal load on the power transistors.


Internal resistance measurement. For comparison, I’ll show the results from the YR-1030 tester. The difference is substantial, but there’s an important caveat—and actually more than one. The thing is, the charger and the tester use different measurement principles: the charger measures with DC, while the tester uses AC. Datasheets for batteries often list both values, and DC resistance is higher than AC resistance.
Also, DC resistance depends much more on the battery’s state of charge than AC measurements do.


I couldn’t resist taking the power supply apart. First off, I liked that the case is held together with clips rather than glued shut.


The board inside is clearly a used one, which is good news, especially since it’s most likely a name-brand unit.


1. A proper input filter with two inductors, a thermistor, and a 470 V varistor. The input capacitor is 68 µF.
2. A Rubycon capacitor in the PWM controller’s power supply circuit. But that’s not the interesting part: the power supply has not only output overvoltage protection, but also a thermistor for overtemperature protection!
3. Two diode assemblies are mounted on a small heatsink; they’re the ones that “lit up” in the thermal image. There’s also a rather nice-looking transformer nearby. The power supply has a common-mode choke on the output.
4. The output capacitors are Rubycon too, both rated for 25 V, but with different capacitances: 1500 and 820 µF.


Everything is neatly laid out on the underside: the PWM controller, its surrounding components, the feedback circuit, and output overvoltage protection. All in all, my hunch was right: this is an excellent power supply, and it definitely earns its $6 price tag.


Conclusions—there’ll be a lot of them today, and they won’t all be clear-cut.
Let me start by saying that the charger works well and does everything it’s supposed to do: it charges and discharges batteries, measures capacity accurately, can restore batteries, does a decent job of “detecting the delta” when charging Ni-Cd and Ni-MH batteries, won’t let you set a high charging current for “weak” batteries, and generally selects the charging current correctly on its own.

Now for the “caveats.”
Charging.
Overall, it works well. The charger can easily charge all four slots at once at up to 3 A, doesn’t overcharge, starts at 500 mA by default in manual mode, and in automatic mode sets 2–2.5 A depending on internal resistance for high-current cells.

Discharging
My only gripe here is the discharge method itself: it’s pulsed rather than linear. Otherwise, no complaints: two slots go up to 1 A and the other two up to 0.5 A.

Capacity measurement
Everything is great, except that after the discharge cycle, charging takes place at just 250 mA (500 mA in auto mode). That takes a long time—a very long time...

Restoration
It works and can help restore Ni-Cd and Ni-MH batteries, and possibly lithium batteries too, though that’s trickier. I simply don’t recommend using cells in that condition. It can also reactivate a protection circuit that has shut down due to overdischarge.

Overall.
Compared with the “Opus,” this charger has a higher charging current and no annoying fan. But thanks to its fan, the Opus can discharge all four slots at 1 A, while this one can only do two.
Since the charger has a high charging current, it comes with a pretty decent power supply—unlike the ones bundled with the Opus chargers, which sometimes wouldn’t start properly when all four slots were occupied, or would get hot as ovens.

Controls.
On the one hand, the charger is easy to use. On the other, my old one was even easier, but it wasn’t as flexible because you had to select modes for all four slots at once. After two months, I’ve pretty much gotten so used to the new charger that I no longer notice the difference in the controls. Still, I’d like to be able to set the charging current manually not just for the first stage, but for the other stages in capacity measurement mode as well.

Drawbacks.
I see two main drawbacks: no LiFePO4 support and a low charging current in capacity measurement mode. You could also complain about the lack of HV Li-ion support, but there aren’t many batteries of that type. Both drawbacks could be fixed in software, but there’s a safety concern: you could insert a LiFePO4 battery and the charger would charge it to 4.2 V. That’s exactly why the Opus has a switch inside the case.
Pulsed discharge. It’s a drawback, but to be fair, most chargers like this work the same way.

Did I like this charger? Yes and no. It works well and measures capacity reasonably accurately, but I’d still like to see LiFePO4 support, more settings, and the option to control the channels synchronously.

That’s all from me. I hope this was useful. If you have any questions or examples of tests you’d like to see, I’ll be happy to answer. I may add more information as I continue using it.