Hello, I would like to ask a question to see if anyone can help me. A few days ago I had a breakdown in the Multiplus II 48/5000/70 Inverter and in the Pylontech Us5000 batteries that I am waiting for to be returned repaired. The fact is that I have the MPPt 250/100 at home and when connecting to the photovoltaic panels I get these errors error 86 and error 39, is it normal because there is only the MPPT without connecting to anything or is it also broken? It also puts 127 volts on the panels and 123 on the battery when there is no battery
Why is it switched on if there is nothing (no battery) connected?
Just disconnect the panels.
There probably isn’t a permanent problem but there will be if you don’t shut it down.
Read the manual here.
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ALWAYS connected the battery first.
It’s not designed to work without battery.
You should disconnect the PV and hope that you didn’t kill the MPPT.
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Okay - so what happens if you have Lithium Batteries and they shut down due to temperature being too cold or low voltage. This will disconnect battery from MPPT. From what you are saying then this cound damage the MPPT. What is the solution here
Thank you
The BMS has a charge and discharge MOSFET. When it’s too cold, it will disable the charge MOSFET, and when it’s too low voltage, it disables the discharge MOSFET. If it has a voltage disconnect, it will reconnect as soon as the sun comes up.
Thanks for the reply Owen
There may be installations with different batteries with different BMS - so are you saying that the MOSFET in BMS will shunt the current coming from MPPT and thus protect it from damage? There are multiple reasons why a Lithium Battery may shut down and my concern is that if user is not on site to disconnect the PV then MPPT will get damaged according to Victron product manual
If you blow a fuse or trip a breaker between the MPPT and the battery, it can lead to problems. In such cases, the MPPT is likely to be damaged. Additionally, if there is an issue with the battery while the MPPT remains connected to the bus and equipment, you might observe the array voltage on the battery side of the MPPT, depending on how the MPPT has failed. I have a few small installs on 12V and 24V systems with MPPTs. I use a battery protect from the MPPT battery output to the system in case it fails, and it will overvoltage disconnect. I have a large array 5460W peak, but I use the isolated 450/100.
If you are not connected to a battery, there is a risk of damaging the MPPT or the entire system.