I had 2x Victron 100/20 MPPT on my setup. 1x 300A shunt, RPI4 Venus. They were working without a problem over 2 months. One of them almost caused fire. I am glad I was close by. I heard an unusual sound. I got close and I smelled it right away. And I then I saw the smoke. I immediately turned off the battery and PV lines. My system is 24V
It burned my 24v to 12v converter and my 24v inverter.
I checked voltages one charger at a time. I immediately saw battery terminal voltage was at 80v when the MPPT2 charge controller was on. Basically it was giving the same pv voltage to the battery side. That’s why it burned my inverter and dc converter. Over voltage. Back of the dc converter melted to the wall. Smokes came out of the inverter. MPPT1 was normal. But unfortunately MPPT 2 damaged MPPT1 as well. MPPT1 looked normal but it turned off. Basically stopped charging. No way to enable it back on again.
Because , it was not an over current issue, all fuses were normal. None of the fuses were burned.
I check youtube. I guess there are several videos on this issue. Battery terminals , output side, burn for some reason. Victron should come up with better and more reliable terminals. Possibly they should separate them little away from each other ,
i am glad it happened when I was there. If I was not there, it was a guaranteed fire.
I tried to call their customer service but they are in Netherland, I couldn’t find a local number in California or USA.
Be very careful. I will try to find out why it happened. I cannot think of any reason for now, other than just bad luck.
This same thing happened to me on the 100|50 MPPT. Output voltage to the battery was the same as the PV voltage - 44V on a 12V system. It caught my stove lights on fire and burt up several of the overhead 12V lights in my camper. Luckily I was in the camper when the stove lights started burning and pulled the fuse or it could have been catastrophic. I couldn’t believe it when I saw 44.3V on the system. Traced it back to the charge controller. No corroded wires or loose terminals. I haven’t pulled it out yet (just disconnected it), I have a replacement on the way. The system is only 3 years old and professionally installed at the dealership (if that even means anythng other than it’s not a DIY system).
My understanding is the larger sccs like a 250/100 have a monitoring circuit and relay that will trip if the pv shorts to battery, to avoid cooking the battery and other equipment.
Perhaps that doesnt exist on the smaller sccs?
And then the rs450s are galvanically isolated so such a failure mode isn’t possible at all.
These charge controllers are non-isolated, which means that any internal fault could expose the battery side to high voltage from the PV source. It is essential to include a battery protect between the chargers and the battery. The 12-24V battery protect is typically rated up to 65V and will disconnect if the voltage coming out of the MPPT charger exceeds 16.5V. By designing the system with these parameters in mind, you can prevent such failures. There are many examples online where people have included them in their schematics.