32 minutes ago, Tinbum said:

It has everything to do with incorrect charge voltage. The battery requests a max charge voltage and if the inverter doesn't follow it then the fault is with the inverter. They always recommend the master battery being the battery with the latest Firmware. Pylontech have changed the max voltage requested from 53.2v to 52.8v so he is better off going with the latter as his inverter seems to overrun and having the lower value may help to protect the other batteries slightly.

Limiting the amps to 90A will do nothing as at near 100% SOC the amps are way less than that anyway and the battery will limit them to a lot less that that.

I'm certain they will say the cell has been damaged because the battery has been subjected to over-voltage- it's not the battery causing the over voltage. The cell over voltage is a result of the battery over voltage. Pylontech are normally ok with their warranty claims when it is a battery fault but I can't see them accepting this as one.

I don't need to use AI to see results.

The highest pack voltage recorded across all provided logs is 53631 mV (53.631 V)

Well below 54V max and the exact same value mine goes to and many thousands of other people using Sunsynks/pylontech. Here is a more concise version as it seems you are having trouble understanding what the issue is.

Pylontech US3000C Diagnosis

• Issue: Severe cell imbalance — cell 13 has significantly lower effective capacity (~30–50% less than others).

  • On charge: Cell 13 rises fastest → triggers OV protection early (pulsing/throttling, high OV counters).

  • On discharge: Cell 13 drops fastest → limits usable capacity (pack hits ~6% while others ~78–91%).

  • At sustained 100%: Passive balancing partially masks it (smaller delta, other cells appear high).

• Cause: Common degradation in these packs after cycles/partial charging; weak passive balancer can't fully correct large mismatch.

• Current Impact: Reduced real-world Ah, frequent protections, but pack still functional/safe (SOH 93%, no faults).

Recommendations

1. Immediate: Avoid discharge below 20–30% SOC. Slow charge to 100% and hold (float ~53.4–53.6V) for days/weeks.

2. Best fix: Install a dedicated active balancer (strongest community solution):

   • Servtec 1A (plug-and-play retrofit for US3000C) — highly recommended.

   • Alternatives: Heltec/JK 5–8A capacitive (wired to cell taps).

3. Long-term: Contact Pylontech for warranty/service if possible. Regular full charges for prevention.

This resolves/manages the issue for most users without replacement.

3 minutes ago, Nexuss said:

The highest pack voltage recorded across all provided logs is 53631 mV (53.631 V)

Well below 54V max and the exact same value mine goes to and many thousands of other people using Sunsynks/pylontech. Here is a more concise version as it seems you are having trouble understanding what the issue is.

Pylontech US3000C Diagnosis

• Issue: Severe cell imbalance — cell 13 has significantly lower effective capacity (~30–50% less than others).

  • On charge: Cell 13 rises fastest → triggers OV protection early (pulsing/throttling, high OV counters).

  • On discharge: Cell 13 drops fastest → limits usable capacity (pack hits ~6% while others ~78–91%).

  • At sustained 100%: Passive balancing partially masks it (smaller delta, other cells appear high).

• Cause: Common degradation in these packs after cycles/partial charging; weak passive balancer can't fully correct large mismatch.

• Current Impact: Reduced real-world Ah, frequent protections, but pack still functional/safe (SOH 93%, no faults).

Recommendations

1. Immediate: Avoid discharge below 20–30% SOC. Slow charge to 100% and hold (float ~53.4–53.6V) for days/weeks.

2. Best fix: Install a dedicated active balancer (strongest community solution):

   • Servtec 1A (plug-and-play retrofit for US3000C) — highly recommended.

   • Alternatives: Heltec/JK 5–8A capacitive (wired to cell taps).

3. Long-term: Contact Pylontech for warranty/service if possible. Regular full charges for prevention.

This resolves/manages the issue for most users without replacement.

Quote at the bottom of AI.

"AI responses may include mistakes. Learn more"

We have already seen his batteries at 54v in earlier posts.

31 minutes ago, Tinbum said:

Quote at the bottom of AI.

"AI responses may include mistakes. Learn more"

We have already seen his batteries at 54v in earlier posts.

haha ok i admit i did not look at the other batteries and add up the voltages i apologize for missing that ! I only looked at the history data of pack 2,

from the picture he posted in post nr one the voltages of the packs are as follows:

Battery 1: 54.196 V

Battery 2: 52.87 V

Battery 3: 53.972 V

Battery 4: 54.118 V

Very high indeed .... lets see what the other packs history shows if their cells are more balanced . Pack 2 being lower voltage and the rest that high is certainly interesting. i would keep a close eye on that to make sure they dont go that high again , maybe even disable comms and use voltages if necessary. flashing the new firmware for lower charging voltage could be helpful i agree ,just doesnt make sense why it would go this high in the first place .

You only have to look at;

Pwr OV Times : 6923

Pwr HV Times : 15041

5 minutes ago, Nexuss said:

haha ok i admit i did not look at the other batteries and add up the voltages i apologize for missing that ! I only looked at the history data of pack 2,

Glad you find it a lauging matter! How about an actual apology for saying things like 'Here is a more concise version as it seems you are having trouble understanding what the issue is.'

That was my first post in this topic!

And your post;

Edited February 7Feb 7 by Tinbum

A good example of why I don't use AI. The example highlighted being taken from wrong information given/suggested on this very forum!!!

Question- Have SunSynk 8kW users reported battery voltage going too high?

Yes — there are reports from users of SunSynk systems, including 8 kW models, where the battery voltage appears to go unusually high or triggers over-voltage faults, though it’s not clear how widespread this is. Here’s what’s been discussed by installers and owners online:

🔋 User/Community Reports

1. DC high voltage fault (battery)
Some SunSynk users have reported seeing a DC over-voltage fault (e.g., F55 / DC_VoltHigh_Fault) where the battery voltage spikes above expected limits — one example was a reported jump to ~62.6 V on a system with a BMS over-voltage set at 56.8 V. The inverter logged an over-voltage fault but then recovered.

2. Reports of potential overcharging with certain battery brands
In forum threads, users hypothesize that certain combinations — SunSynk 8 kW inverters with Seplos-based BMS batteries like some Pylontech or Shoto packs — may allow the battery to be driven to high charge voltages that risk exceeding safe cell charging levels. One long-running thread suggests this may be a real issue rather than just user error, though there’s no official confirmation. (https://powerforum.co.za/topic/17822-sunsynk-overcharging-batteries-pylontech-shoto/?utm_source=chatgpt.com)

Edited February 7Feb 7 by Tinbum
sp.

41 minutes ago, Nexuss said:

Pack 2 being lower voltage and the rest that high is certainly interesting.

That was all ready discussed here in my second post;

Edited February 7Feb 7 by Tinbum

Morning @Tinbum and @Nexuss , thanks again for the above analysis.

I've went and gotten all the logs from the other 3 batteries (so 4 in total). Looking at the logs this morning it seems that even with the new floating voltage alot of the cells are reporting as high and I am seeing OV and HV warnings / errors.

I think one of you clarified this for me yesterday but just that I understand correctly, if I am using LiBMS this should request / override any settings in the battery settings pages such as the float voltage and charge current? All my charge current on the inverter is set well below the max. Is there a voltage setting that is still affecting the charging of the batteries?

Which settings affect the OV and HV issues that I am getting?

Some additional info regarding my battery bank.

Battery 1 is the newest yet it cycles a lot more than the others, it was bought about 3 years after the initial 3 batteries, it is also the master. Software version 24-07-01.

Battery 2 is the current trouble child. Software version 24-07-25.

Battery 3 currently working as expected. Software version 24-07-25.

Battery 4 currently working as expected but the main board was replaced late last year as it just packed up one day. Software version 24-07-01.

I also had to send in all of my configuration screenshots from my inverter and photos of my install for the RMA, at which point no issue was raised about my floating voltage either.

All battery software was upgraded by Segen last year. They stated that even though I have the same batteries because of different main boards etc the software versions are the latest / correct for that board and battery.

An observation, all the batteries are exhibiting some kind of error / warning OV/HV. These errors are only visible via a specialised cable and via non-publicly available software (you can't just download it from the website). The errors are not surfaced via the inverter, or via the warning light and signal on the batteries themselves. The standard monitoring app doesn't even show individual battery status / level. I could only see the level of my individual battery dropping because I have extra monitoring software (Solar Assistant) and I have the special cable for more detailed info.

So how is a normal user supposed to know something isn't right? When the system was setup by a legitimate installer, checked by an electrical engineer (for safety sseg).

Attached is the zip file with all of batteries event and history logs. Appreciate any further input.

Thanks and regards,

J

logs-08022026.zip

1 hour ago, JuliusK said:

I think one of you clarified this for me yesterday but just that I understand correctly, if I am using LiBMS this should request / override any settings in the battery settings pages such as the float voltage and charge current? All my charge current on the inverter is set well below the max. Is there a voltage setting that is still affecting the charging of the batteries?

Yes your LiBMS screen indicates your comms is working so the float voltage and other voltages on that settings page does nothing(only the charge and discharge amps is what u can/should set). You as the end user can not change the charge voltage unless you disable comms and switch to voltage mode , or install the newest firmware which limits charge voltage (this should not be needed usually). You as the end user did nothing wrong is what i am saying . Somewhere between the inverter and batteries there is a fault causing the charge voltage to go too high.

2 hours ago, JuliusK said:

All battery software was upgraded by Segen last year. They stated that even though I have the same batteries because of different main boards etc the software versions are the latest / correct for that board and battery.

This seems like it could have something to do with the problem , i would go back to Segen and provide logs to them , battery 2 needs to be swapped or have that cell 13 replaced and they all need a firmware update for lower charge voltage. Initial looks at the other packs history does not indicate any other weak cells but i am still going though them all .

Can you post some historical graphs from solar assistant for battery voltage /BMS voltage? would like to see what the inverter is recording voltage wise daily.

I also notice the logs only provide data for this year ? Seems like Segen deleted the old data which is not ideal. edit * just remembered the history is cleared with firmware updates .

Edited February 8Feb 8 by Nexuss

42 minutes ago, Nexuss said:

Yes your LiBMS screen indicates your comms is working so the float voltage and other voltages on that settings page does nothing(only the charge and discharge amps is what u can/should set). You as the end user can not change the charge voltage unless you disable comms and switch to voltage mode , or install the newest firmware which limits charge voltage (this should not be needed usually). You as the end user did nothing wrong is what i am saying . Somewhere between the inverter and batteries there is a fault causing the charge voltage to go too high.

This seems like it could have something to do with the problem , i would go back to Segen and provide logs to them , battery 2 needs to be swapped or have that cell 13 replaced and they all need a firmware update for lower charge voltage. Initial looks at the other packs history does not indicate any other weak cells but i am still going though them all .

Can you post some historical graphs from solar assistant for battery voltage /BMS voltage? would like to see what the inverter is recording voltage wise daily.

I also notice the logs only provide data for this year ? Seems like Segen deleted the old data which is not ideal.

Thanks for clarifying the settings for me. I was worried.

I'm going to open a RMA case for battery 2.

I took all of the log files (both events and history for each battery) and ran them through claude.ai and the analysis I got back is not positive. According to to claude this is the executive summary of my battery bank. Battery 1 is the best of the bunch with only a cell imbalance, battery 2 has complete BMS failure (plausible), battery 3 identified cell 10 over-voltage, battery 4 critical cell 14 over voltage. So I don't know if is accurate or just ai hallucinations. The report reads like a Stephen King novel.

Attached is my battery voltage for the last year and 1 month. On the 1 month graph you can see a definitive change, this is exactly when battery 2 dropped to 7% SOC the first time.

1 hour ago, JuliusK said:

Thanks for clarifying the settings for me. I was worried.

I'm going to open a RMA case for battery 2.

I took all of the log files (both events and history for each battery) and ran them through claude.ai and the analysis I got back is not positive. According to to claude this is the executive summary of my battery bank. Battery 1 is the best of the bunch with only a cell imbalance, battery 2 has complete BMS failure (plausible), battery 3 identified cell 10 over-voltage, battery 4 critical cell 14 over voltage. So I don't know if is accurate or just ai hallucinations. The report reads like a Stephen King novel.

Attached is my battery voltage for the last year and 1 month. On the 1 month graph you can see a definitive change, this is exactly when battery 2 dropped to 7% SOC the first time.

I don't use SA. Where does it get its data from?

I'm suspecting the inverter. Your graphs dont show the voltage going up to 54v but the batteries do. Could the inverter be misreading voltage? Probably. It may well be worth just putting a voltmeter on the batteries to clarify.

I think I would be going back to the installer saying you suspect the inverter has a voltage reading/control fault and has ruined your batteries.

41 minutes ago, Tinbum said:

I don't use SA. Where does it get its data from?

I'm suspecting the inverter. Your graphs dont show the voltage going up to 54v but the batteries do. Could the inverter be misreading voltage? Probably. It may well be worth just putting a voltmeter on the batteries to clarify.

I think I would be going back to the installer saying you suspect the inverter has a voltage reading/control fault and has ruined your batteries.

SA has two USB cables, one that goes to the inverter and a second that goes to the console port of the master battery. However I do not know which data is being plotted on the graph, the average of all 4 batteries or the inverter values. The additional USB to the batteries does give the ability to see the individual batteries SOC, voltages etc.

I'm going to get the installer involved tomorrow.

Don't agree with AI that your BMS has failed- that's wrong. Not even looked at any other things it says.

Just had a very quick look at the logs and the main think that is obvious is;

Edited February 8Feb 8 by Tinbum

On 2026/02/06 at 6:46 AM, JuliusK said:

"0V" state.

That is actually OV not 0V standing for "Over Voltage".

31 minutes ago, Tinbum said:

That is actually OV not 0V standing for "Over Voltage".

Most of my batteries are in a high voltage state or an OV state. Is there anything that I can do to reduce that or it's a bms thing?

1 hour ago, JuliusK said:

Most of my batteries are in a high voltage state or an OV state. Is there anything that I can do to reduce that or it's a bms thing?

I'm pretty sure it's because your inverter isn't following what the bms is requesting. I don't have your inverter but know you could set it with manual settings rather than communicated settings. That does have disadvantages though. As your setup looks to have had this problem for some time, maybe from installation I'd leave it alone until you've spoken to your installer. They should be the one sorting it and the last thing you'd want is them saying it because you've altered settings.

I noticed from your postings that you had the inverter repaired some years ago. Perhaps it's something to do with that? I wonder if they require calibration and that wasn't done?

8 hours ago, Tinbum said:

I noticed from your postings that you had the inverter repaired some years ago. Perhaps it's something to do with that? I wonder if they require calibration and that wasn't done?

That's correct, it was due to the wrong firmware being installed by the manufacturer during an upgrade.

Something is not right since the battery is asking something and not getting it.

13 hours ago, JuliusK said:

Most of my batteries are in a high voltage state or an OV state. Is there anything that I can do to reduce that or it's a bms thing?

Reading trough this tread resurfaces my old question: What can BMS comms do better than proper inverter settings?

My inverter settings with no comms according to battery specs for 15 cells are: Bulk charge 53V held for 1 hour, float charge 51.5V. These values have never been exceeded. With these settings healthy battery cells never go into OV state.

Edited February 9Feb 9 by Beat

1 hour ago, Beat said:

Reading trough this tread resurfaces my old question: What can BMS comms do better than proper inverter settings?

My inverter settings with no comms according to battery specs for 15 cells are: Bulk charge 53V held for 1 hour, float charge 51.5V. These values have never been exceeded. With these settings healthy battery cells never go into OV state.

Lots and personally I think it's dangerous not to use it.

The manufactures don't put communication in their bms's just for fun. It is the first line of defense in protecting a battery.

I use communication and I've never had a single over voltage or any error on any battery.

The case here, I believe, is a faulty inverter and I think even with manual settings the batteries would have gone over voltage.

Edited February 9Feb 9 by Tinbum

2 hours ago, Tinbum said:

I think it's dangerous not to use it.

I strongly disagree with you. From my experience with BMS weird behavior I get goose bums thinking those could control the inverter. Inverters are designed to manage charging on the base of battery voltage. That information never lies.

3 minutes ago, Beat said:

I strongly disagree with you. From my experience with BMS weird behavior I get goose bums thinking those could control the inverter. Inverters are designed to manage charging on the base of battery voltage. That information never lies.

Battery charging should not just be controlled by battery voltage.

The BMS takes into account individual cell voltages, cell temperatures, charge currents, discharge currents etc etc.

I think this thread has shown the information in the inverter lies.

5 hours ago, Tinbum said:

The case here, I believe, is a faulty inverter and I think even with manual settings the batteries would have gone over voltage.

Now what about the many BMSes like JK where the BMS performs the protection on a temp, each cell basis managing the voltage levels perfectly. It tends to do a better job than some OE BMSes and it does not use comms. If the inverter is at fault the BMS will stop charging/discharging and switch the battery off to protect every cell.

Most if not all parameters can be set to match the cell values from the manufacturer.

9 minutes ago, Scorp007 said:

Now what about the many BMSes like JK where the BMS performs the protection on a temp, each cell basis managing the voltage levels perfectly. It tends to do a better job than some OE BMSes and it does not use comms. If the inverter is at fault the BMS will stop charging/discharging and switch the battery off to protect every cell.

Most if not all parameters can be set to match the cell values from the manufacturer.

The JK BMs has comms.

Just now, Tinbum said:

The JK BMs has comms.

Model specific. I have 3 without comms and blue tooth to the APP. The non comms one is what I indicated in my post.