question

Thanks Alexandra. I am using the victron specific cable for the UP5000 (Type A).

I never touched the Pylontech pins on any of those we installed ( may be 20 systems with 1 to 8 batteries) ! . I may have to do some more research on that side.

You are not the only one to experience problems with Pylontech cables, see here

fyi it's getting worse and stayed off a few hours last night.

Hi Alexandra ; Thanks . No ESS here ; using Virtual switch . Low voltage inverter shut down is at 48 v . Never reached so far below 49 + v .

Follow up: It has become worse with more shut down, and staying longer OFF . See below picture for last night . I can only go on site tomorrow . Customer had no power during shut down as his AC IN is wired via the Multiplus . Based on Daniël Boekel comments on AC IN / Inverting , as soon as the system came back ON , I forced AC IN by removing Virtual switch settings from VRM access . Now AC is on passthru . And "so far" , it seems to hold . ??? Does it change something for any of you in the troubleshooting approach ?

Could this happen if the Cerbo is faulty ? Client tells me he "thinks" he noticed that the Cerbo was OFF just before the system went off yesterday ... If Cerbo is OFF, indeed , the Multi looses BMS information . He may think battery is low and shuts down ? When checking the errors on the remote console , it says low battery, and it says Error # 67 : BMS com lost for both charge controllers ? Just trying to think of everything and what to bring with me !!!

Fun part now ! Went on site with 2 new Pylontech UP5000 with the idea of swapping them and bring the 2 others to our lab to investigate . Did so. Left the customer's place back to lab . Not even reached , got a call from customer saying exact same problem happened ! So now : 1- Installed one of the 2 initially "faulty" batteries at our lab and monitoring the system. So far, after 5 hours . All seem fine . 2. Tomorrow will connect the computer to the battery and download data . Then plan to test the 2nd battery alone , and then, finally, put them back together and monitor. System by the customer is for now forced on AC IN (passthru) and working well like that !!! Back to the drawing board to try to understand what can be wrong.

So here below it shows it happened again a few times with the same "low battery alarm" although : The system was on passthru . batteries were at 100% . Inverter was never "inverting" . And these are brand new Pylontech UP5000 batteries .

For info, we don't find any evidence of issue on the battery side . However, interestingly we ran a test and disconnected the power supply of the Cerbo (to simulate a Cerbo fault) while having the inverter on "inverting" , with VS settings . . I can confirm the inverter would shut down after a little while . That's on our bench ; not by the customer . With our test inverter and cerbo working seamlessly.

for those interested in the results of the test ; the problem comes from the cerbo. the cerbo works; it's on and works. it seems it regularly sends wrong information to the multi and to the mppt's , making them think the batteries are low or off ( bms error 67 on mppt , low voltage alarm on multi). accordingly, when on inverting mode, the multi ends by shutting down and stays off for a few minutes. with red alarm low battery voltage lit. it then starts back on its own. we tested the same cerbo with 3 different systems and it always happen . unable for now to say why or what exactly is wrong with the cerbo, but no doubts it's the culprit !