Unless you’re using the 450/100 or 450/200 models, which are galvanically isolated, it’s essential to install a BatteryProtect. With non-isolated MPPTs, an internal failure can result in high voltage appearing on the low-voltage side—a serious risk to your system.
A BatteryProtect device is designed to disconnect in the event of such a fault, preventing damage. There are numerous examples where BatteryProtects have successfully prevented overvoltage issues caused by MPPT failures. I use them on all my systems, and in my opinion, not including one is a mistake.
The picture you have is a description of 2 different systems; you will not get installation instructions from this. You can ask your supplier for help with system design and how to install a battery protect to protect the system from a fault in the MPPT. I have blown up a few Victron products and found they can help, and very knowledgeable.
I have no idea, just an example I found of a battery protect between the MPPT to the battery to protect from an MPPT fault. This is how it’s done. Most people with small systems will put a 12V panel on a 12V system or a 24V panel on a 24V system and will not see multiples of the system voltage if there is a failure. If you want to fly close to the sun and run at near MPPT max voltage input, then you really need to look at something like this.
Pretty sure high voltage shutdown is around 66v, but the 48v system might only have a design insulation voltage of 80v, like fuse holders etc. The system would have definitely alarmed and shut down, but would not have been able to protect itself from extreme voltage.
I have given up on communicating with the Victron guys. They never replied on questions for the reasons why the safety measures didn’t work. They only point towards me for causing the voltage to go above the capacity of the MPPT.
The last mail I received even stated that there are no safety measures in the MPPT that will help preventing accidents caused by overvoltage. Then I have had enough of it.
I have passed the issue on to my lawyer to see if they can get an answer that will give more clarity to the situation. I wil wait and see…
When switched on, the “run” lights were on, but there was no voltage on the terminals.
I have fitted new BMS cards to the units and now they are operational again.
I will keep them in case something else goes wrong with the new cards or I might repair them in the future.
I know which parts are damaged in the old cards and maybe I will repair them. The current problem is that the onboard fuses are only sold in quantities of thousands. Maybe I can get my hands on a smaller number of them.
If I am going from a high-voltage to a low-voltage, I will always use a galvanically isolated product or install a battery protect. I think any charge controller above 32V should be galvanically isolated for safety. That would be ideal. Relays can fail.
Even though the MPPT isn’t isolated, it has built-in protection circuitry that monitors the system.
If the voltage or current coming from the solar panels goes out of safe range, that protection circuitry will shut off power to the converter before anything bad happens.
Because of this protection, there is no risk that a dangerously high voltage will reach the battery side — the MPPT will disconnect it first.
However, he emphasizes that you must stay within the maximum input values (voltage and current) stated in the datasheet, because that’s the limit the protection circuitry is designed to handle.
As long as you respect those limits, the MPPT will stay safe under all conditions.
Basically,
The MPPT watches itself and can disconnect if something goes wrong — but you still have to wire and design it properly, because if you exceed its absolute maximum ratings, no amount of smart circuitry can save it. Did you also go over current? I know if the current is over the rated input the reverse polarity circuitry will be damaged.
My solar installations are mainly low-voltage panels, parallel connected.
So I’ll have a Voc of 20+ volts for a 12V battery, I dont believe the 20V can do my battery or the other electronics harm, if the current goes directly from the panels to the RV its in a low range, it might just charge my batteries a bit slower…
