I have a very basic system. I have tried setting the system with an MPPT 75/15 as well as an MPPT 100/20. These controllers were alternately connected to a 12v 200ah LiFePO4 battery, 165 W PV and 12v Dometic Refrigerator. The refrigerator has a battery saver that shuts off the refrigerator if the voltage drops below 10.1v. The system works fine during the day, but as the sun goes down the refrigerator stops until the sun comes up.
I have extensively tested the system and setup variables and have the following conclusions:
1) The controller obviously controls the voltage and current flow between the BATT, PV & LOAD connections.
2) The voltage and current varies significantly between the Battery Terminals and the above connections.
3) The voltage significantly drops on the controller BATT, PV & LOAD connections when compared to the Battery Terminals at night.
For example, with the controller LOAD set to "Always On", the voltage will drop in the controller to a voltage much less than the Battery Terminal voltage when the PV levels drop. A simple test showed:
Battery Terminal Voltage 13.2v and the LOAD voltage (calculated and measured) at 14.1v with the PV connected.
Battery Terminal Voltage 13.2v and the LOAD voltage (calculated and measured) at 9.8v (varies a lot) with the PV disconnected
If I connect the refrigerator directly to the battery, it runs fine through this day/night transition. If I connect it to the LOAD it stops at night due to the voltage drop. Why is there a voltage drop when there is no PV input. With an "Always On" setting, shouldn't the controller simply pass through the voltage and the current directly from the Battery Terminals?
Sure, I can connect the refrigerator to the battery, but then I lose the data that the App provides. Plus I do have 12v outlets that I use to connect other devices. It appears that the controller limits the LOAD output to less than a couple tenths of an amp at night...
Seems like a flaw to me. Anyone else have this problem or are you all using the Streetlight function at night?
