Hello for my first post.
I have a 3 Phase Multiplus II 48/5000/70 System with an MPPT RS450 and a BYD LVS20 Battery.
Yesterday evening, at no PV Input, and only very limited charge of below 500W/phase, the Multiplus II on L3 made a Thermal Alarm and shortly after this, a termal shutdown.
Today I tried to investigate to locate the Problem, and compiled the following analysis. (See attached image)
Did anybody have a similar behavior?
The system is running since a few weeks now, but this behavior is really strange.
Firmware of Multiplus II is 498.
Thanks for some hints
Detailed description:
13.12.2024 21:21:24 Temperature Alarm on L3 while max Feedin = 4000W
13.12.2024 21:21-21:26, max feed in goes up to 32 kW ???
13.12.2024 21.25:44 Thermal shutdown on Multiplus II L3, stops all 3 Multipluses in 3 Phase config
13:12.2024 21:26:10 switch off and on of Multiplus L3, booting
13.12.2024 21:26:29 Temperature Alarm again with feedin again up to 32 kW ???
13.12.2024 21:26:56 Thermal shutdown on Multiplus II L3 again. waited a few minutes, switched on and back to normal.
How on earth can this happen, max Feedin is limited on Cerbo to be 8900W for total of 3 phases, and in VE.Configure the
Maximum AC current for charge or feed in 62.5 % of 5000W =3125W
At that moment, Input and output power was below 500W per phase!!, even during the event!!
Ambient room temperature 19°C
Addendum:
17.12.2024 15:43 , Another Thermal shutdown, this time without the peaks in the max feed, but again with very low charge at the moment of the shutdown.
Rewrote all the configuration settings to the Multiplus II on Phase L3 through VE.configure to exclude a software glitch. A few minutes after booting the Multiplus, fan came back to full speed again!
21.12.2024 In the days after 17.12, the fan permanently running, but as before only for the Multiplus II on L3, not for the 2 others, I decided to upgrade all the Multiplus II to the lastest available firmware, so from 498 to 552. Apparently some temperature calibration problems have been fixed in one of the newer firmware releases.
31.12.2024 Warnings on temperature are back again since 3 days. Fan only on Multiplus on L3 back to full speed.
Decided to have a look with the infrared camera on the Inverters to see if there is something special.
Interesting to see, the chassis of the Multiplus on L3 is colder than the ones on L2 and L1. Logical, only the one on L3 has the fan on full speed, the other’s fans are off. Room temperature between 18°C and 20 °C.
The only explanation left is a hardware problem on the Multiplus on L3.
As explained in the “multiplus___quattro___testing_and_diagnosing.pdf” document, either one of the PTC’s for temperature surveillance has a problem, or, there is a hotspot on one of the boards provoking one of the PTC’s increasing his resistance and the temperature control is working as designed to prevent the Multiplus from going up in flames.
I do not want to loose warranty by opening the cover. If opening the cover does not void the warranty, I could provide infrared images of the interior to further narrow down an eventuel hotspot.
04.01.2025 After a discussion with my dealer, I’m going to ask for an RMA on the Multiplus on L3. Let’s see what happens next. I’ll keep you updated.