FL-4H-LCD-D, or a charger from an unknown manufacturer.

Batteries have somehow started multiplying unexpectedly at my place. Since I also needed to test quite a few batteries, I decided to get a charger with a capacity measurement function. But buying the well-known Opus, Soshine, or iMax would have been too obvious, so I decided to try a charger that few people have heard of.
As always, the rest of the story is after the jump.

As I mentioned in the introduction, I needed a charger with a battery capacity measurement function, since I sometimes have to test several dozen batteries.
I didn't want to buy one of the well-known models, so I settled on a dark horse whose reviews I hadn't seen before. I thought it might be interesting.

The charger arrived without a box, simply packed in a resealable bag, so this is minimalism in its purest form :)


The entire package consists of just the charger and its power supply. There are no instructions, warranty cards, or anything like that.
The charger's screen had a protective film on it, and it was very thick—I haven't seen one like that in a long time. I removed it right after taking the photos.


Unfortunately, there was no adapter included, and the power supply has flat prongs.
The cable is a little over a meter long.


The power supply doesn't even specify its output voltage.
My measurement showed that the power supply's output is 12 V, with positive on the connector's center pin. Everything is standard, so many common power supplies can be used.
When operating, the power supply gets a little warmer than room temperature, so everything is great here.


At readers' request, I opened up the power supply and took a photo. It turned out to be even better than I expected.
On the input side, there's a fuse and a proper mains filter, two power filter capacitors rated at 10 and 22 µF, a PWM controller IC and a MOSFET. One of the output capacitors is LowESR; the other is a regular one.
It's neatly made, with no issues. I haven't seen a bundled power supply of such good quality in a long time.


And here's the charger itself.
Specifications:
Number of channels — 4 independent channels
Charging current — 0.5/1 A; the default is 0.5 A (measured: 0.5/0.99–1).
Discharge current — 0.25/0.5 A; the default is 0.25 A (measured: 0.25/0.49–0.5)
Reverse battery protection — yes.
Short-circuit protection at the terminals — yes
Overcharge/overdischarge protection — yes
Indicators — LCD screen and an audible signal when each operation is complete.
Supported battery chemistries — Li-ion, Ni-Cd, Ni-MH (automatic detection)
Supported battery sizes — 10340, 14500, 22650, 17650, 10440, 18650, SC, AA, 14650, 17670, AAA, 18700, 17500, C, 25500, 16340 (RCR123), 26650
Charge termination voltage for Li-ion — 4.21–4.22 V; for Ni-Cd and Ni-MH — 1.45–1.48 V.
Discharge cutoff voltage for Li-ion — 2.85 V; for Ni-Cd and Ni-MH — 0.9–0.92 V.

By default, the device starts in simple charging mode at 0.5 A.
In charging mode, the device simply charges the battery.
In capacity measurement mode, it first fully charges the battery, then fully discharges it, and then starts charging again. The cycle ends when charging is complete.

The charger is controlled with just one button.
Short presses — switch the charge/discharge current
Long press — switch between charging and capacity measurement modes.
Short press when the backlight is off — turns the backlight on; it switches off automatically after about 20–30 seconds.


There’s nothing interesting on the bottom at all—not even a sticker.
There are four rubber feet, though, so the charger doesn’t slide around on the table (at least while it’s still new).
The grille on top is just for show, purely decorative.


Of course I had to take it apart, especially since it’s a device I’m not familiar with :)

Now we can move on to the real-world tests.
Since this is my first charger of this type, I tested the things that seemed worth checking to me.
If I missed anything, let me know and I'll check it.
First, I decided to test the battery reverse-polarity protection.
If a battery is inserted the wrong way around, it simply displays NuLL, just as it does when there's no battery.
The second battery in that channel continues charging normally.


A quick aside: I like the backlight. I initially expected something bright blue that would burn my eyes out, but no—the backlight is pleasant, and the brightness is set just right.


While charging, the display shows the number of mAh delivered to each channel, but once charging is complete, the figures are replaced with the word FULL.


At first I was disappointed. I thought they could have made it possible to see how much charge had gone into the battery. But as it turned out, pressing the button displays the mAh delivered to each channel for a short time (about 10–15 seconds).


I tested a full charge/discharge cycle on the batteries from this review.
That test measured the battery capacities (in the order the batteries are installed in this photo) as follows:
626 — 610 — 622 — 244
As expected, the charger from that review read slightly high, since the discharge current was only 0.5 A (the previous test used a current of 0.8 A).
731 — 699 — 702 — 298


After that, I ran a test on another set of batteries whose capacity I know.
The previous readings were:
2010 — 2010
This charger read:
2225 — 2259
It's worth noting that the readings differ somewhat. During testing, I noticed that channels 1/2 and 3/4 aren't synchronized. You can see it in the charging indicator: one channel clearly counts time a little faster, while another counts a little slower.
But the difference is actually insignificant, at around 1%.
The battery-shaped indicator shows the charging process: as the battery charges, the bars gradually fill the icon, and during discharge, the reverse happens :)
The higher readings here can also be explained by the difference in discharge current.


The next test was just for fun. I have four Ni-MH batteries that are about 13 years old. Naturally, I wanted to see how bad their condition was.


I tested them in two modes: 0.5 (0.25) A and 1 (0.5) A, respectively.
The result was a pleasant surprise. For such ancient batteries, which had spent several years lying in a desk drawer before being revived and put back into use, a capacity loss of just 40% is pretty good.



And here's a group photo of batteries in various sizes. You can see that only two 26650 batteries can be installed, alternating them with smaller batteries.
But this is common with most chargers, so I don't consider it a drawback.


Summary.
Pros
Classic circuit design.
Simple controls
Backlight
Protection against inserting batteries incorrectly
Capacity readings are fairly plausible.
Protection against reverse polarity at the charger's power input.
Duplicated negative contacts using guides and a wire.

Cons
Loud beeper (though that's a matter of taste)
Gets very hot when discharging four batteries at maximum current.
No support for batteries with a higher end-of-charge voltage, or for LiFePO4 batteries. There is a more advanced version of this charger, the FL-4H-LCD-A, but it's more expensive :(

My take: I think this is a pretty good charger. The most obvious flaw is the heat buildup. Some heat is unavoidable during discharge, but the manufacturer could at least have provided ventilation, not to mention an additional external heatsink or a small fan. The circuit design is simple and robust: charging is handled by a PWM DC-DC converter, while discharge uses a constant current, with heat dissipated by a power transistor and resistor. In my opinion, current regulation is reasonably accurate.
I was pleased to see the negative contacts properly designed. The connection never dropped out, even when I plugged in a multimeter on the fly to measure charge and discharge currents.
They certainly fitted a loud beeper, but opinions may differ; some people might find a regular one too quiet.
Of course, this charger won't win any awards for measurement accuracy, but it's accurate enough for most applications. At least, I liked it. A bit of a workhorse, even if it's gray :)

The charger for this review and testing was provided by the gearbest store.

As always, I look forward to your questions and additions in the comments.

The product was provided for review by the store.