Nexuss

Other way around , Nr 1and 3 disconnects because they are full first there is no overvoltage, then Nr 2 catches up,the 89-90% pause to balance packs is a pylontech thing , i see the same behavior with the middle battery in my stack as the top and bottom battery receive slightly more current. A graph showing the current flow into each battery would confirm this.

There is nothing wrong with using BMS comms and going to 53,5v . Been doing it for 5 years , over 10MW discharged at 93% SOH currently . What was the highest pack voltage that you saw ? seeing one or two cells at 3.9V would be possible under specific conditions but for the entire pack to be at 58,5 would be very unlikely as the BMS would have to request that charge voltage which it would never do with comms . What i suspect happened is that when you were using the lower charge voltage on the Axpert for those 2 years the individual cells were not hitting the top end of the charge curve thus they were not balancing properly , over time this caused great imbalance. Then when you connected the comms and the higher charge voltage was requested some individual cells hit 3,9 as the pylons really suck at balancing the cells if they are severely imbalanced. Post the batteries cycle history/log files here if you can.

I run them down to 5% every day for the last 5 years, currently they are at 93% SOH . There is also a lower balancing point between the packs at 11% SOC.

That's normal behavior for different age batteries , the packs balance at 89-90%. I see the same thing with mine.

Its a shame to see , i actually received excellent support from Deye for my Sunsynk ,crazy to see but there is no good reason to go Sunsynk over Deye anymore .

100% agreed , that's why i cycle my batteries down to 5% every day This is something Will prowse was preaching since way back , he cycles from 0-100% for that reason. The fastest way for the batteries to pay for themselves is to use all your capacity every day (leaving a small buffer at the end if needed for loadshedding/grid failure depending on you usage)

I have had good service from apexium,fast shipping , great packaging , excellent quality cells.

If @GreenFields is correct about your panels you may likely need 550W canadian solar or ja solar as alternative, they have a higher VOC rating and lower short circuit current rating AFAIK. You need to get the exact panel information from your installer so we can advise you properly.

You need a minimum of 5 panels to keep the MPPT "awake" consistently. Your string voltage with 4 panels is too low.

No as its well within the MPPT specs. I would only oversize like this on East /West split style arrays. If all the panels were facing north there is not much reason to go much more than 6,5Kw of panels so in that case i would not go more than 16 panels.

You can add another 8 on the other MPPT. Thats what i am running. You could do 9 on each string maximum.

53 degrees is pretty hot , how long does the temp stay there ? does it go up quick at the end of charging and then back down pretty quick after fully charged ? I have only seen this behavior on the new chip pylons and that battery serial on your picture is old chip if i am correct which would make this even more suspect. Could also be faulty temp sensor or the BMS starting to fail ,hard to know , try batteryview and check what it does when you go from 95 to 100% SOC. I have seen my new chip battery peak at about 46c when balancing.

No , on some days when the battery is fully charged early in the day it will tend to overshoot a bit .Its not constant and varies according to loads. I have seen this on a few sunsynks so its not something that can be fixed by the end user if you are using BMS comms.

Got some 280Ah cells a few months ago from apexium . 108 dollars a cell shipped to your door from the local warehouse. https://www.apexiummall.com/index.php?route=product/category&path=232_249

If its on a 5kw Deye as your signature suggests thats because the MPPT is limiting the current . Ive seen my 455W panels peak at about 12,8A aswell thats about the max the 5kw unit wil do.

here is a nice copy paste for you as i am too lazy to type... Earth neutral bonding is an important aspect of electrical safety and system performance, particularly in solar power systems like those with Sunsynk inverters. Here’s a breakdown of why it’s required: 1. Electrical Safety Ground Fault Protection: Proper earth neutral bonding ensures that if there's a fault in the system, such as a short circuit, the fault current has a safe path to the ground. This helps in quickly clearing faults and protecting both people and equipment. Prevents Shock Hazards: By bonding the neutral to earth, you help ensure that exposed metal parts of the electrical system don’t carry a dangerous voltage relative to the ground, reducing the risk of electric shock. 2. System Performance Stable Voltage Levels: Earth neutral bonding helps maintain stable voltage levels in the system by providing a reference point for the neutral. This can improve the performance and efficiency of the inverter and other electrical equipment. Reduced Electrical Noise: Proper bonding can minimize electrical noise and interference, which can be beneficial for sensitive electronic components within the inverter. 3. Compliance with Electrical Codes Regulatory Requirements: Many electrical codes and standards require proper earth neutral bonding to ensure safety and performance. Compliance with these regulations is necessary for both legal and insurance reasons. Manufacturer’s Specifications: Sunsynk and other inverter manufacturers often have specific requirements for earth neutral bonding to ensure the system operates correctly and safely. 4. System Reliability Consistent Operation: Proper bonding contributes to the reliable operation of the inverter and other electrical components by providing a stable reference for the system’s electrical circuits. Troubleshooting: With correct bonding, it’s easier to troubleshoot and diagnose issues within the system, as the ground and neutral have a defined relationship. In summary, earth neutral bonding is crucial for ensuring the safety, performance, and compliance of a solar power system. It provides a secure path for fault currents, helps stabilize the system, and ensures adherence to regulatory standards. If you’re setting up or maintaining a Sunsynk inverter system, it’s essential to follow these guidelines carefully to ensure everything operates safely and effectively.

The 12kw 3 phase inverter has internal bonding relay , just make sure signal island mode is ticked in the settings.

Is that on the master inverter ? make sure the comms between the inverters is working .

Sounds like you have SOC set too high for the daytime. If the battery is at 100% and the corresponding timeslot SOC is set to say 50% it should supplement with the battery.

Is that really correct? how can it be that bad?

Because the battery is full.

It may be that the battery was run down too low and is in protection mode. You could try to wake it up via the console port. See below link. https://github.com/helgeerbe/OpenDTU-OnBattery/discussions/603

Ok thanks ,looks like they are trying to take advantage of you . Cells at3,6V does not cause swelling ,cells under 3,65V is still perfectly safe and should not cause a failure. They are only giving you a small snippet of the log in that document, for you to fight this with more probability of success you will have to get a consol cable and pull the BMS log yourself to get the events and history logs. Then post that history and event pdf's here. We can then go though the complete life of the battery and determine how it has been behaving. The amount of high voltage logs suggests it was faulty from the start. Also pull the logs from the working battery so we can compare them. If you can present them with clear cut data that it was not your fault pylon should honor the warranty. All the info on how to pull the logs are on the forum. You have to load batteryview to save the history files.

Hi Martin , can you please post all the log/history/event files from the battery so we can try to determine what happened to it .

This will be tricky to diagnose remotely ,you might want to mention where you are located so someone close might be able to help.