*** UPDATED 3-7-2020I have lowered my initial rating to 3 stars. The first unit I received worked well and I really liked it, but after 3 months it suddenly failed (would no longer apply any load). The distributor (SRA-Solder) replaced it without hassle, though it took a few weeks and cost me fifty bucks for shipping. (Note: They would have paid shipping if the failure had happened within 30 days, but after 30 days and up to 1 year, customer pays return shipping.)Unfortunately, the replacement they sent had an entirely different problem, right out of the box - the voltage measurement was wrong (large offset at 0, plus additional error as voltage increased). The distributor agreed to replace the second unit, and this time sent a prepaid shipping tag. BUT... They subsequently told me that ALL the units they had in stock exhibited the same problem, some with voltage errors, some with both voltage and amperage errors.I ended up requesting a refund, and will look at other brands. The design has a lot of bang for the buck, and honestly I really liked the first unit I had (until it completely failed). Getting a second bad one in a row seemed like bad luck, but then the distributor confirmed similar (and worse) issues with other units in stock -- and no "new stock" expected for several months.Support from the distributor was fast and very good. The representatives I dealt with were all professional, understood my problem descriptions, and proposed reasonable options. Ultimately, they stood behind the product and offered replacement or refund as promised under the warranty. Unfortunately, all the units they had in stock had similar issues, and new stock from China (which might or might not be better) wasn't expected for several months.*** ORIGINAL REVIEW 8-11-2020 ***Very nice device with lots of features / capability for the price. I have mainly used it in CC (constant current) mode, but did test out CV (constant voltage), CR (constant resistance) and CW (constant wattage), and they functioned as expected. Values for voltage/current can be entered directly via the number keys, or using the rotary encoder. Operation of these modes are easy and obvious from the front panel.The 5 memory keys can be used to save common setups, including the mode (CC/CV/CR/CW) and values. These are easy to use and saving/recalling is obvious; press the button to recall it's stored settings, or press "shift + save" buttons, then a memory number 1-5, and press enter to save current mode and settings to the chosen memory location.The Battery test mode allows setting current, voltage cutoff, and max time cutoff, and you can save up to (10) sets of these parameters. When the test is started, the defined load is applied and cumulative current calculated until the voltage or max time is reached. Setting up this mode, and saving/recalling settings, is NOT intuitive or easy. You will pretty much need the user manual to set or change the parameters for Battery test mode.There are several "dynamic" modes which allow defining variable / repeating loads or pulsed loads with specific duty cycle and frequency. Like the Battery mode, programming them is non-intuitive and complex, and WILL need the user manual in hand. And even with the manual, it is a bit confusing.The fan only operates when needed. For example, I ran a 12v/1.2A CC test in a 68F room and the fan cycled on/off for about 40 seconds every few minutes. At higher currents, it will run continuously. The fan is fairly loud, but it is a reasonably low frequency and not obnoxious.Though not mentioned in the product description, the KEL103 comes packaged with: AC cord, USB cable, Serial cable, two very nice 36" #10 awg flexible spade leads (one red, one black), user manual, and software CD. There are NO instructions in the user manual regarding the supplied software, and the manual itself is pretty brief and not that well translated.The main Windows software provided installs a Korad-branded copy of LabView 2014 and the National Instruments "Virtual Instrument Software Architecture (NI-VISA) runtime library. This worked immediately via USB or Serial, but not over Ethernet. (NI-VISA apparently supports TCP over ethernet, but not UDP because UDP lacks error-checking and acknowledgment.) The KEL103 only speaks UDP, so LabView and NI-VISA won't work with it via Ethernet.When I connected the device to Windows10 via USB, it was recognized and enumerated -- but no USB drivers were loaded by Windows10 and it showed up in device manager with a "no drivers loaded" error. There are drivers on the supplied CD, but the instructions for installing them use very old Windows (xp?) dialogs in the examples, and the instructions didn't work for me. What did work: Find the "USB-K-R-Com Port 2.0.inf" file in the "\software\USB driver" folder of the CD, right click the file, and choose "Install".I found some very useful open source examples (in python and C++) on Github that allow programmatic control / query of the the Kel103 using SCPI commands via UDP over Ethernet. However, I still struggled with getting the Ethernet port activated. Apparently the only way Korad provides to setup Ethernet parameters (i.e., dhcp/static, address and gateway if static) is another utility named "kel103.exe" from the "\test command" folder of the CD. That utility will *usually* find the kel103 over ethernet via UDP broadcast, but other times it fails and needs a USB/Serial connection. (Note: The Korad-branded LabView 2014, installed to "\program files" is also named "kel103.exe" -- but the kel103.exe in the "\test command" folder of the CD is a completely different program, despite the identical name.)To try without USB drivers loaded: Connect an ethernet cable to the kel103, then launch the "kel103.exe" utility from the CD's "\test command" folder. The utility title should be "Kel103 Assistant". Click the "Network Debuger" (sic) tab, click the "Scan devices" button, and wait for the kel103 to be detected and displayed in the list. Click on the device in the list, set DHCP/Static parameters as desired, then click the "OK" button just below the DHCP fields to save. Power cycle the KEL103 to finish.If the "Kel103 Assistant" can't find your Kel103 on the network, load the USB drivers and connect a USB cable as described earlier. Then launch the "Kel103 Assistant" utility ("kel103.exe" from CD's "\test command" folder). Choose the "USB Debuger" (sic) tab, click "scan devices" and wait for the KEL103 to be shown. Click on listing, then click the "Open USB" button. Now you can set DHCP/Statid parameters as desired, and click the "OK" button just below the DHCP fields to save. Power cycle the KEL103 to finish.The KEL103 should now have the DHCP address you assigned, or one pulled via DHCP from your router. Check your router's device list or use a network discovery tool if needed to identify the DHCP-assigned IP address. The KEL103 will respond to ping, so that's a good way to test basic network connectivity.The KEL103's capabilities and bang-for-the-buck rate 5-stars, but I have to drop a star due to the sketchy documentation, confusing software, brief and incomplete user manual, and difficult Ethernet setup (as well as lack of any supplied software to use Ethernet access). Of course all the "basics" can be easily accessed from the front panel, so the USB / Ethernet / Drivers / Software are all irrelevant if you are content using the front panel. But if you want the ability to access, control, and monitor via software over Ethernet (for example, I wanted to create voltage-over-time graphs of batteries at specific loads) --- be prepared to do a little research and coding on your own.