The DL24 electronic load represents an entire line of low-priced yet capable testing devices that are all similarly built.
While they may not support extremely high currents or voltages compared to more pricey lab equipment, they are sufficient for typical load testing in hobbyist labs.
There are a number of slightly different hardware versions available. Some come with USB input connectors mounted to the main PCB while others ship with a USB extension PCB that can be connected to screw termials when needed.
The device comes without a housing. A microcontroller and built-in firmware supports providing constant current (CC), constant voltage (CV), constant resistance (CR), and constant power (CP).
| Feature | Description |
|---|---|
| Over-Current Protection | >21A |
| Over-Temperature Protection | >100C |
| Overload Protection | >185W |
| Timer Cutoff | Cut-Off after interval |
| Voltage Cutoff | Under-Voltage Protection |
| Calibration | Current-calibration interface |
| Test Connections | Terminal, USB-C, Mini-USB, Micro-USB, Barrel Jack |
| Interfaces | Bluetooth LE, USB |
| Software | PC-Program, Android App |
Warning
This electronic load is rated for testing power supplies outputting up to 200V and/or up to 20A (at a maximum power of 150W).
These specs do not go inline with the way the device and its components are designed. When getting even close to these values, chances are high that the MosFET will explode with a bang.
Reviewing the many blog posts who thoroughly tested this (and similar) loads, you should definitely stay below 32V (which makes sense from a safety aspect anyway), and keep currents under 10A. That said, these safe values are still more than sufficient for most hobbyist needs.
Setup
The device requires its own power supply via a connector on its back. Do not confuse the power jack with the jack located on the right side of the device (which is a calibration output). Always use the jack at the back of the device. This jack is clearly labeled “power” on the PCB.
You may want to exchange the included AC power adapter with a better 12V 1A power adapter: the included adapter came with a US plug and a EU plug adapter that easily fell off.
Once power is connected, the screen briefly shows a company logo, then displays the settings for the currently activated mode. By default, CC mode is preselected:
Connecting Test Power Supply
Electronic loads are used to simulate a load so they are used to test power supplies. Whether these are DC-DC-converters, batteries, or even solar panels: by connecting the electronic load to such a power supply, you can test and monitor its behavior under stress (load).
The power supply that you want to test is connected to the four screw terminals on the left:
You can either connect wires to the terminals (there are two screw terminals per pole), or use the included adapter plate to add USB connectors.
With the USB adapter plate, you can easily connect a USB power supply or a USB power bank to the electronic load.
User Interface
The device is controlled by four buttons on the right side of the display. The buttons are labelled on the PCB: Setup, +, -, and Start.
Changing Modes
The electronic load supports four main modes:
- Constant Current (CC): The load adjusts the voltage in order to maintain a constant current. This mode is typically used to discharge a battery with a constant current.
- Constant Voltage (CV): The load maintains a constant voltage by adjusting the current.
- Constant Resistance (CR): The load acts like a programmable resistor and creates the resistance chosen by the user.
- Constant Power (CP): The load draws a constant power by adjusting its resistance, based on input voltage.
To switch the fundamental load mode, press and hold Setup. Once the main mode display at the top of the screen starts to blink, use + and - to switch to another mode.
If you do not press + and - quickly enough, the display changes back into the current mode and lets you change its settings.
The picture below shows the CR mode where the electronic load creates a fixed resistance:
Changing Settings
To change the settings for the current mode, press Setup and release it immediately.
Main Setting
A cursor appears, and you can use + and - to change the main setting, or press Setup again to move the cursor to a different digit.
What exactly the main setting is depends on the mode you are using. In CC mode, for example, you’d set the current (Is) that you want to keep constant. In constant voltage (CV) mode, this setting would be the desired constant voltage instead.
Additional Settings
To change additional settings - such as setting the timer, or defining a cutoff voltage, press Setup for 1-2 seconds. The main mode display starts to blink.
Press now Setup again (short press) to move the input cursor to one of the other settings. You can now use + and - to adjust these settings.
Invoking Load
To turn on the load, press Start. The load now starts to draw energy from the connected power supply.
Depending on your settings and the amount of power, the big fan starts to run in order to cool down the mosfet and dissipate the heat that it is burning.
If the load does not turn on when pressing Start, the display explains why and highlights conflicting settings. If for example you are in CC mode with a cutoff voltage set, then the load will only turn on if the connected power supply delivers more than the cutoff voltage. If not, or if the power supply isn’t turned on, or if no power supply is connected yet, the load won’t turn on.
Temperature Probe
The device comes with an attachable temperature probe:
The temperature is displayed at the bottom of the screen. The probe can be attached to powerbanks or power supplies under test in order to ensure they do not overheat.
System Menu
Long-pressing Start opens the internal system menu where you can change advanced settings:
- Language (Chinese/English)
- Reset counters (total time, capacity, energy)
- Nulling voltage and current
- Calibrating voltage
- Current calibration
- Display brightness (active)
- Display brightness (standby)
- Time to switch to standby mode
- Calibration of temperature probe
- Calibration of external sensor
- Setting maximum current, initially 185W (should be lowered to <150W)
- Factory defaults
- Save and Exit
Remote Control
The device can be remotely controlled via Bluetooth and USB.
For Android smartphones, there is a free app that can be used to connect to the bluetooth connector. There is no app for iOS. ou can use bluetooth with free custom apps though.
A Micro USB port on the right side lets you connect the device to a computer. The device can then be read and controlled via a USB cable (included). Either use the PC software supplied by the vendor, or use free tools that reverse-engineered the protocol.
The DL24 protocol seems to be compatible to TX100. Tools designed for this load seem to work at least with some versions of DL24.
Apparently, there are also ready-to-use generic software solutions that can read and chart output from this electronic load.
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(content created May 14, 2024)