Review on LANGY Solar Battery Charger Controller, 20Amp, 12V/24V Auto Recognition, Large User-Friendly LCD Display, Compatible with Flood, Lead Acid, Gel, Lithium Battery by Mike Carter

In terms of display and operation procedure, this solar PWM controller is almost identical to another similarly priced controller I own. The manual that came with this controller is just as badly written as the others. I spent a lot of time figuring out how to work with the other controller, so I had no problem figuring out how to work with this one. It is actually quite simple. First connect the battery. Once the battery is connected, the controller display will scroll the values for 3 parameters (i.e. BAT Voltage -> BAT Temperature -> PV Voltage). However, the PV voltage displayed is the actual output voltage of the solar panel only when its value is lower than the battery voltage. If the panel output voltage is higher than the battery voltage, then the PV voltage displayed is some sort of regulated voltage that always seems to be equal to the battery voltage, making it useless (see attached video). I turned off the solar panel at the moment shown in the video and measured the output voltage of the panel. It was about 18B. The user manual says the user can provide values for 5 parameters (Float Voltage, Reclose Voltage, Load Disconnect Voltage, Charge Mode and System Voltage Selection). That is not right. The controller will automatically set "System Voltage” to 24V when the battery voltage is above 18V and 12V when it is below, so there are only 4 parameters to set. Initially, the controller has default values for them. To change, press the Menu button until the option you want appears. Then press and hold the "Menu" button until the display flashes. At this point the value can be changed with any key. To save the changed value, either press and hold the menu button until the flashing stops, or wait 20 seconds and the controller will return to the cycle display mode. Connect the solar panel after checking the settings. Saved settings are retained even after power off, so check the settings before each use of the solar panel. After the change, I haven't found any other way to reset the parameter values to factory defaults other than manually changing the parameters one by one. This inexpensive PWM solar controller works as advertised but is nothing special. It would be nice if the controller always displayed the panel's output voltage and current, but this is not the case. The displayed PV voltage is only conditionally meaningful and actually somewhat misleading. I think this controller is suitable for small one-off projects. But for larger permanent installations, I would go for the more efficient and powerful (but more expensive) MPPT solar charge controller.