ZKEtech EBC-A10H Electronic Load

A little over three years ago, I reviewed the ZKE EBC-A10 electronic load, which quickly became one of my main instruments for battery testing. You’ve probably seen both the load itself and the graphs I included in my battery reviews.
The device turned out to be genuinely useful, and as far as I know, my review was either the first or one of the first. But it’s time for an upgrade, so today I’ll be talking about the new version of this load.


First, let me answer the question: why did I buy a new load when I already have one?
There are several reasons:
1. Quite simply, one load is no longer enough for me.
2. The new load is more powerful.
3. It also lets you set the current as low as 50 mA, rather than 100 mA. That matters for battery testing, since datasheets often specify the end-of-charge current at exactly this level.


But I actually went a step further and bought two new loads, plus a small add-on for them. I’ll talk about the rest another time.
At first, I thought about buying one on AliExpress, but it costs $85 there. Fortunately, one of my regular readers, who also sponsors some of my reviews, offered to help me buy them. Many thanks to him for that.
I ordered two loads through him, and he placed the order with the help of a Meest Express forwarding service. The loads cost me about $95, plus around $3 for the add-on and $30 for shipping, bringing the total to almost $130. Buying everything on AliExpress would have come to nearly $200, which I think is quite a bit more.

Delivery took about two weeks. The box weighed almost 3.5 kg; you can get an idea of its dimensions from the photos. I could have saved money by having the items repacked and shipped by train, but I wanted them sooner, so they were sent by air.

Both loads were packed in inflatable air cushions, with bubble wrap as well, and arrived with no visible damage.


The package includes:
1. EBC-A10H load
2. Power leads with alligator clips
3. Interface cable
4. Power cable
5. Manual and warranty card.

The seller actually offers two listing options. The second one is about $8 cheaper and doesn’t include the interface cable, power supply, or power cable. You can buy the interface cable separately for $3 or $4, saving $5 that way, and I already have plenty of power supplies. Unfortunately, this package option isn’t available right now :(


I’ll start with the extras.
Everything is packed in separate bags, so it looks quite neat and “professional.”


The manual and warranty card—the latter isn’t valid here—and the manual is in Chinese, so we’ll skip this part. If you need it, there’s an English description of the software online, which is more than enough in practice.


1. Power cable. As they say, I wouldn’t take this even for free—especially since I first paid for the cable itself and then for shipping, and it has a Chinese plug. It’s also a standard “computer” power cable, which most electronics hobbyists or computer users already have plenty of.
2. A set of leads for connecting to a battery or power supply. The wires are very flexible. If you order the load and the leads are sold separately, I recommend not skimping and buying them.
3. Unlike my load, this one has four alligator clips instead of two, which makes the connections more flexible in some situations.
4. The power terminals are copper and marked 30 A. The wires are soldered on rather than simply crimped.
5. The interface cable is useful, but can easily be replaced with a standard USB-TTL RS232 cable if needed.
6. The connector for the load comes in three types from ZKEtech:
MiniUSB, though it isn’t actually USB; they’ve just used the same connector. Nothing will burn out if you plug in a USB cable, but it won’t work.
A 3- or 4-pin aviation connector. You’ll need to check the load itself, since the connector type isn’t always specified. Mine has 4 pins; the seller offers both options, and the one I ordered came with the 4-pin version.


The load.
The enclosure has clearly been redesigned. My version was simply housed in a power supply case, while this one has a proper, larger enclosure with a built-in power supply and standard terminals. The paint job is neat, and there’s really nothing to complain about. Well, perhaps it could use a handle that doubles as a stand.


The controls have changed too: the four buttons have been replaced with a push-button encoder and a start button. The functionality is essentially the same, but it’s more convenient to use. On the other hand, I used the manual controls once, when I reviewed the previous version three years ago. Since then, I’ve only used computer control.
The display—well, that’s self-explanatory.
There are four terminals: two power terminals, marked A+ and A−, and two sense terminals, V+ and V−.
The terminal layout is awkward: the positive terminals are on the left and the negative ones on the right. There’s no way to change that, at least not without the labels on the case still being wrong.


There are ventilation slots on the sides. At the back are a fan, a power input, an illuminated switch, and a fuse.
There are four feet on the bottom, so the load doesn’t slide around on the table.


There’s also a warranty seal. It was already trying to peel off on its own; the photo shows what happened after I tried sticking it back on :)
But since the warranty won’t do me any good, let’s remove it.


The case design is simple and straightforward: a U-shaped cover and an L-shaped base.
The cooling design is well thought out. The fan cools the heatsink, charger, shunt, and power supply all at once.


The cooling fins for the power stage extend out on the right side. Based on my experience with my own high-power load, I can say that the heatsink doesn’t have much headroom.


Everything else is on the other side.


For some reason, they used a slim fan. I’d have gone with a more conventional 20 or 25 mm one. My high-power load also has a slim fan, but there wasn’t enough room, so that was a necessary compromise.


I was impressed by the neat workmanship: the wires are terminated, and all the connectors are secured with hot glue. But whoever routed the interface wires under the power supply without any extra insulation deserves a slap on the wrist.


Speaking of the power supply, there’s not much point in describing it in detail. It’s the well-known “people’s” 24 V power supply. I might test it at some point, since my review from four years ago is clearly out of date.
The power supply is rated for 100–120 W, and the charger will deliver roughly comparable power with it (20 V, 5 A), so there’s no need to replace it—especially since it has active cooling here.
I’ll probably modify the charger and replace the PSU, though the latter is still up in the air.


The power board.
There’s not much to describe here. It carries the charger, the regulator for the controller, the shunt, transistors, and other small components.


Actually, there is one important difference: this version has a relay.
The thing is, a bug showed up in the old version of the load—and it was a dangerous one.
The charger is controlled by a controller, and everything would be fine if there weren’t two ways to control it:
1. The controller enables the charger
2. The controller disables the charger

This design uses the second method: the charger always starts up, and the controller switches it off. If you apply power with a low-voltage battery connected and the power supply isn’t powerful enough, an overload occurs and the PSU goes into protection mode.
The controller then fails to start, while the charger keeps hammering the battery, trying to charge it up to the voltage needed for the controller to start. I’ve already learned this the hard way and nearly killed a battery.

The manufacturer fixed this in the newer units: power from the charger goes through a relay, which only connects when the charger needs to run, preventing the situation described above.


The power stage uses two IRFP250M transistors connected in parallel. At least, I couldn’t see any current-balancing circuitry.
There’s a 50-degree thermal switch next to one of them. The fan has two speeds: the controller switches on the first when power exceeds 10 W, while the thermal switch controls the second.

There are terminals for connecting a thermistor near the transistor, but they aren’t used.


The charger is exactly the same as in the previous version, so there’s nothing new here. I’d like to replace the inductor with a more powerful one, though.


The controller board—there’s nothing new here at all. Hardware-wise, it’s identical to the board in my previous load; the only difference is the firmware. I just thought of something: could read protection be disabled...


We turn it on and see the same dreary LCD, even though I need it only a little more often than the keypad. I do look at it from time to time, though. But I definitely don't want to replace it.


In manual mode, the screen displays:
1, 2. Operating mode, current voltage and current, as well as time + capacity in mAh and current power + capacity in Wh.
3, 4. The same information while running.
5, 6. There are CC (constant current) and CP (constant power) modes. Unfortunately, there is no CV mode, which would have been useful.
7–11. But what surprised me is that it has charging modes for different types of batteries. LiPo mode also works with Li-Ion batteries, since they're essentially the same thing.
12. There's also a manual charging mode, where you set the current and voltage yourself.


Before the tests, here are the technical specifications—first, the original version, in Chinese.


And now, a brief translation of my own.
Power supply: 19–24 V, 4 A, or 220 V if the built-in power supply is installed
Input voltage range: 0.00–30.00 V, measurement resolution 0.01 V
Output voltage range: up to 18 or 22 V; this specification isn't entirely clear.
Load current: 0.05–10.00 A, setting resolution 0.01 A
Charging current: 0.05–5.00 A, setting resolution 0.01 A
Load modes: CC, CP
Charging mode: CV
Voltage measurement error:
Up to 4.5 V: measurement resolution 0.003 V, error ±0.5%
From 4.5 to 30 V: measurement resolution 0.01 V, error ±0.5%
Current measurement: 0.05–10.00 A, resolution 0.01 A, error ±0.5%
Capacity measurement
Up to 10 Ah: resolution 0.001 Ah (1 mAh)
10–100 Ah: resolution 0.01 Ah (10 mAh)
100 Ah and above: 0.1 Ah


Now let's move on to the tests.

First, the input voltage measurement accuracy. The charge termination voltage setting accuracy is tied to it as well.
As far as I can tell, there are no issues here: the accuracy is decent, although I can't shake the feeling that my old load is calibrated a little more accurately.

The last two photos show the maximum input voltage. If you exceed it, an overload warning appears.


There are a few quirks. Although the specifications give a resolution of 0.01 V over the 4.5–30 V range, in practice this isn't always the case. For example:
1, 2. We change the input voltage by 0.01 V, but the load doesn't register the change.
3, 4. We change it by the same 0.01 V, but the voltage shown on the load's display changes by 0.03 V.

This doesn't happen every time, but it does happen.


The load current set by the load and measured with a multimeter.
The load is within the specified error, but only just. This is especially noticeable at 10 A, where a 0.5% error should give a range of 9.95–10.05 A. The current reads slightly low across the entire range. That doesn't matter in normal use, but when testing battery capacity, the result will be overstated by the same amount. For example, a 9.96 Ah battery will show up as having a capacity of 10 Ah.

If needed, I can calibrate all this myself, but I'll leave it for now and see how it behaves over time.


Test of current-setting temperature stability.
This is a very important test, because with a poor-quality shunt, the current can change significantly as it warms up.

There is a slight drift, but as it happens, it's in the right direction: the error decreases as the unit warms up.


This load has the EBC designation and, unlike the EBD series, also includes a charging function. So next, I'll check the charging current setting accuracy, since that affects the accuracy of capacity measurements while charging.

It's almost exactly the same as in discharge mode, so if you want, you can try a hardware correction by slightly reducing the shunt's nominal resistance with a resistor in parallel. The difference from a software correction is that it's hard to break anything this way :)
By the way, over time my load started reading low in one mode and high in another, i.e. the zero has shifted, which is worse.


Here, as it heats up, the current drops slightly.


I already covered the software in my previous review, so I'll keep this relatively brief and point out the differences.
Several years have passed since the previous review, and the software has been updated periodically, but nothing has changed fundamentally.
The key update is that current and voltage are now displayed with the same resolution as on the load; older versions showed one fewer decimal place.
Also, all modes are saved on the load itself. For example, if you set the charging current, voltage, and so on, then disconnect the load and connect it to another computer, the software will start up there with those settings.

Now, about the software itself.
The main window has a large area for plotting graphs. Current and voltage are displayed by default, but you can also show a power graph, though that's rarely needed.
To the right is the display and control panel, showing the current voltage, the set load current—or the actual current in charging mode—power, and the time elapsed since the test started.
Just below are the mode controls, buttons to start and stop a test, change the load current without stopping the test (in load mode only), and a "Monitor" button. In this mode, the load works as a current and voltage logger without affecting the process.

At the very bottom is a line showing:
The device name, operating mode and settings, voltage at the start and end of the test, capacity in mAh and Wh, average voltage over the entire test, and the colors used for the graphs.


I'll hide the rest of the description under a spoiler, since much of it repeats the description of the first load.


One fairly noticeable change in the newer versions is the ability to use presets for different battery types instead of only manual mode. Unfortunately, this requires support from the load itself, and my old one still can't do that.


The preset charging modes were tested with four types of batteries:
1. Standard lithium-ion
2. LiFePO4
3. Nickel-metal hydride (cadmium batteries are supported here too, but the principle is the same)
4. Lead-acid


Lithium-ion: charging to 4.2 V, with charging stopped when the current drops to 50 mA, regardless of the set charging current. The cutoff is usually set to 1/10 of the charging current, but here it's set to the value most commonly used in datasheets.


LiFePO4
Everything is the same, but charging stops at 3.65 V, when the current drops to 50 mA. It's odd that it charges to 3.65 V rather than 3.60 V. For some reason, I thought the correct charging voltage was 3.60 V.


Nickel-metal hydride.
Here I used a very old battery, about 17–18 years old. While testing this mode, I also decided to try to revive it a little by running charge/discharge cycles. Its capacity was initially 10–20 mAh, but by the eighth cycle it had reached 450 mAh. I didn't experiment any further.
The charging voltage is set to 1.65–1.7 V, but the main cutoff is based not on the current dropping, but on the voltage delta. In other words, the voltage rises during charging, then stays stable for a while, and starts to drop once charging is complete. As soon as the load detects a sustained drop in voltage, it stops charging.
Although this type of battery is no longer very common, it's nice to see the correct charging method implemented.


Lead-acid battery.
Charging stops at 14.40 V, when the current drops to 100 mA, regardless of the initial charging current. In my opinion, that's not quite right, though of course you can always set the mode manually.
You may also have noticed that you can set the number of cells in the battery. It's set to 0 by default; if you don't select a value, it automatically switches to 1 cell when you start. For a 12 V lead-acid battery, for example, you should set it to 6, since it's actually a pack of six cells connected in series.
You can set up to 12 cells in this mode, but in that case you'll probably need to modify the charger itself and use a higher-voltage power supply. So the practical limit for now is a 12 V battery; the theoretical limit is 24 V.



Temperature testing.
1. Operating in load mode at 29 V, 5.05 A, with about 145 W dissipated by the load. The transistor temperatures were within reasonable limits, around 75–80 degrees, but overheating is possible in hot weather. I consider about 90 degrees on the transistor case to be the critical maximum.
2. Charging a battery at 5 A and a voltage close to 4.2 V. The hottest component was the PWM controller, at almost 90 degrees. On the old load, I soldered a tab to the controller's flange to improve cooling; with active cooling, it makes a big difference.
3. Charging a lead-acid battery at 2.5 A and a voltage close to 14 V. The PWM controller was around 60 degrees, so the thermal camera showed the control board's power regulator as the hottest component.


During the maximum-current heating test while charging a lithium battery, I noticed a strange glitch: sometimes the charging current rose above the specified limit, to about 5.03 A. It did return to normal afterward, but how that could happen remains a bit of a mystery to me.


To wrap things up, and at the request of one of my regular readers, I tested how well it works with a power supply based on a DPS-series converter. The load was operating in CP mode at 150 W. I tried various voltage/current combinations, and everything worked perfectly.


Based on the tests and overall inspection, I can say that I liked the load itself and recommend it. The manufacturer has clearly made some improvements to both the design and the circuitry and software. The maximum power limit is now 150 W, up from 60 W on the old model; the minimum current is 50 mA, down from 100 mA; it can now test nickel batteries correctly; and the startup issue with a low-voltage load connected has been fixed.
But there are still a few shortcomings, some of which have carried over to this model.
1. The charger is still weak. Personally, I'm not very impressed, and I wouldn't recommend using it to charge lead-acid batteries at maximum current. The converter's inductor is also a bit undersized for 5 A.
2. The power transistors don’t have a current-sharing circuit like the one I built into my load; they’re simply connected in parallel. This can lead to an imbalance, with one transistor dissipating, say, 100 W and the other 50.
3. It could use a remote temperature sensor (preferably magnetic) to plot the battery temperature.
4. I don’t understand why the manufacturer still uses the microcontroller’s ADC when plenty of inexpensive external ADCs are available.

I also wish it had galvanic isolation from the computer. I’ll install an ADuM, as I did in my power supplies.

Otherwise, I think it’s excellent. And considering it cost about $65 including shipping, it’s really excellent—I don’t know of any competitors at the same price.

Update.
After using it quite heavily for a while, I’ve come across a few issues I hadn’t noticed before.
1. Terminals. Definitely replace them—the stock ones are very flimsy, and a couple have already started turning when tightened.
2. Fan. It’s noisy. It’s better to reduce its speed in “software mode” and solder an improvised heatsink, made from a copper tab, onto the charge controller’s PWM chip.
3. The load’s power supply can cause a lot of interference when it’s connected to both a computer and the device under test, potentially even dropping the USB connection. This doesn’t matter when testing batteries, but it can be critical when testing power supplies. The solution is to use galvanic isolation for the computer connection; replacing the power supply may also help.
4. I knew about this issue but forgot to mention it in the review. When testing protected batteries (not battery packs), the protection board may fail. For example, if the charge voltage is set too high, the battery’s protection circuit may trip before the load disconnects. This problem isn’t unique to this load; it can also occur with some similar devices. The reason is that when the protection circuit trips, it is briefly exposed to the full power supply voltage—in this case, 24 V. The solution is to use a 12 V supply when working with these batteries, either from another power supply or from the main one via a step-down converter.

That’s all. I hope this was useful.