Hi all,

I am hoping that someone may have experienced my issue previously and been able to resolve it.

I have a bank of 4x Pylontech US3000c batteries connected in parallel. Recently (Sunday) one battery in the bank went down to 7%, while others were at their usual plus/minus 50%. I thought this was odd but I let the batteries all recharge back to what I though was 100%, then used the batteries as I did normally, charge from sun during the day, discharge modestly at night. The issue came back again on Monday the same battery went down to 7%, I now knew something was not right.

I hooked BatteryView and called Segen Solar, they advised that the battery cells needed to be balanced. Charge back up to 100% and leave it idling for 72hrs. I took their advice and did just that. The whole time the bank was balancing, battery number 2 charge indicator on the actual battery was the last light always blinking, so essentially stating that it was not yet 100% full.

This morning all batteries in the bank report they are full. I again connected BatteryView and took screenshots of the reports on all the cells. What seems to be a theme that there are cells with a "High" state and on bank 2 there is a cell with a "0V" state. This is only flagged as error on BatteryView the error light does not light up on the external battery warning light. Please see images attached.

So after all that, my question is. Are the "High" and "0V" warnings actual problems or just more of a FYI?

Thanks for your help.

Regards,

Julius

My first impression is that you are charging to a too high voltage!! Your overall voltage looks to be 54v.

Max Pylontech will request is 53.2v or 52.8v depending on firmware.

I would do a discharge/capacity test while watching what they do in battery view.

Their is something wrong if all the screenshot are taken at the same time as the overall voltages are different.

2 hours ago, Tinbum said:

My first impression is that you are charging to a too high voltage!! Your overall voltage looks to be 54v.

Max Pylontech will request is 53.2v or 52.8v depending on firmware.

So below is my configuration for my inverter for the battery charging, but everything is controlled by the BMS.

25 minutes ago, Nexuss said:

I would do a discharge/capacity test while watching what they do in battery view.

What would be the best way to do that. Would I just run a bunch of things at the same time i.e. geyser and pool so there is some load and watch what happens?

14 minutes ago, Tinbum said:

Their is something wrong if all the screenshot are taken at the same time as the overall voltages are different.

Yes, all screenshots were taken with a minute of each other. Should the voltages be identical on all or should they be just close enough?

6 minutes ago, JuliusK said:

Yes, all screenshots were taken with a minute of each other. Should the voltages be identical on all or should they be just close enough?

They should all be identical. 3 of your batteries are showing 54v and the problem battery is less.

You have a setting on your inverter of a float voltage of 55.2v which is way too high if the inverter is following that. If it being controlled by the bms then the max voltage you should ever see is 53.2v or 52.8V.

You should look at the battery logs to see how many over voltage errors their have been. Above 55vthe battery will suffer physical damage and shut off.

Edited February 6Feb 6 by Tinbum

4 minutes ago, Tinbum said:

They should all be identical. 3 of your batteries are showing 54v and the problem battery is less.

You have a setting on your inverter of a float voltage of 55.2v which is way too high if the inverter is following that. If it being controlled by the bms then the max voltage you should ever see is 53.2v or 52.8V.

You should look at the battery logs to see how many over voltage errors their have been. 54v is the max the battery will accept without physical damage and shut off.

Thanks, I'll go get that adjusted. Will also investigate the logs.

Which is the better float voltage for the longevity of the battery, 52.8v?

52.8v is the newer firmware setting.

15 minutes ago, Tinbum said:

52.8v is the newer firmware setting.

Thanks, my battery firmware was updated last year it's a mix of v2.4 and v3.0. Just had a look at the status again of all the batteries and they are now all allegedly fine. This was before I changed the float voltage.

1 hour ago, JuliusK said:

So below is my configuration for my inverter for the battery charging, but everything is controlled by the BMS.

Changing the float voltage wont do anything as you are using BMS comms... Your capacity is not set correctly , 74x4=296Ah

I would also set the charge at least 100A and discharge at 148A.

Edited February 6Feb 6 by Nexuss

1 hour ago, JuliusK said:

What would be the best way to do that. Would I just run a bunch of things at the same time i.e. geyser and pool so there is some load and watch what happens?

It doesn't have to be super accurate run a load maybe +- 2-3kw and watch for errors on battery view(on the battery that was showing 7%) , the capacity is not that important just check that the packs stay close to each other in terms of SOC all the way down the SOC curve from 100% to however low you want to go. They should stay close to each other(within 5%) all the way down to 5-10% SOC.

14 minutes ago, Nexuss said:

Changing the float voltage wont do anything as you are using BMS comms...

That should be the case but his cells were showing 54v so clearly something is wrong.

9 hours ago, JuliusK said:

I hooked BatteryView and called Segen Solar, they advised that the battery cells needed to be balanced. Charge back up to 100% and leave it idling for 72hrs. I took their advice and did just that. The whole time the bank was balancing, battery number 2 charge indicator on the actual battery was the last light always blinking, so essentially stating that it was not yet 100% full.

How exactly did you do this ? Disable the work mode timer ? the cells being at 3,6V each is unusual as @Tinbum is saying . Not sure but maybe it has something to do with your capacity being set incorrectly . So i would change that and do a load test , also paste a picture of your LiBMS screen to confirm that comms is working .

13 hours ago, Nexuss said:

Changing the float voltage wont do anything as you are using BMS comms... Your capacity is not set correctly , 74x4=296Ah

I would also set the charge at least 100A and discharge at 148A.

Morning, thanks for all the info last night.

My apologies, I sent an old photo where I only had 3 batteries and my capacity does appear wrong for 4 batteries. Here is the current and fresh photo.

What is the difference between the Charge and Discharge Amps on the "Batt type" screen and the "Batt charge" screen?

Yes, I disabled work mode timer and let it sit till last night. Tried to run the batteries over night and again it dropped down to 6% this time. LiBMS screen attached. As far as I can see it's communicating OK.

How do you get a list of historic errors from BatteryView? I cannot seem to find that option.

Will run a load test this afternoon once they batteries have charged back up.

11 minutes ago, JuliusK said:

Morning, thanks for all the info last night.

My apologies, I sent an old photo where I only had 3 batteries and my capacity does appear wrong for 4 batteries. Here is the current and fresh photo.

What is the difference between the Charge and Discharge Amps on the "Batt type" screen and the "Batt charge" screen?

Yes, I disabled work mode timer and let it sit till last night. Tried to run the batteries over night and again it dropped down to 6% this time. LiBMS screen attached. As far as I can see it's communicating OK.

How do you get a list of historic errors from BatteryView? I cannot seem to find that option.

Will run a load test this afternoon once they batteries have charged back up.

The capacity is still wrong at 290Ah , it should be 296 Ah . The charge and discharge amps on the batt type screen is what the inverter will limit the battery to . The charging amps on the Batt charge screen is the amps it will use for grid charging only .

There is a option to download "events" under the history data window in battery view.

Edit* you are welcome to post the events and history here so we can have a look..

Edited February 7Feb 7 by Nexuss

1 hour ago, Nexuss said:

The capacity is still wrong at 290Ah , it should be 296 Ah . The charge and discharge amps on the batt type screen is what the inverter will limit the battery to . The charging amps on the Batt charge screen is the amps it will use for grid charging only .

There is a option to download "events" under the history data window in battery view.

Edit* you are welcome to post the events and history here so we can have a look..

Updated my capacity to 296Ah.

Thanks for the offer. Attached is the events and history log file. History is over 3mb so I had to zip it.

event_20260207091159.txt

.history_20260207091211.zip

After consulting AI here is what its come up with :

Historical counters reveal a chronic issue:

• Bat OV Times: 11,862

• Bat HV Times: 12,932

• Pwr OV/HV Times: high (6,923 / 15,041)

  These indicate thousands of overvoltage events over the battery's life (739 cycles, SOH 93% — still decent capacity).

Key Patterns Across All Logs

• At high SOC (99–100%, Feb 5–6):

  • Cell voltages group reasonably well (ΔV ~0.02–0.15 V during low/no current).

  • Various cells hit High/OV during charge (often cell 11 or 12, e.g., 3.613–3.647 V).

  • Cell 13 frequently appears as the lowest (~3.392–3.465 V in some entries), with individual SOC sometimes lagging at 99% while others are 100%.

  • Frequent OV protections and throttling indicate ongoing passive balancing attempts.

• Transition to deep discharge (Feb 7):

  • As SOC drops below ~90%, cell 13 voltage diverges downward rapidly.

  • By 56% pack SOC: cell 13 ~3.179 V (individual SOC 56%), others ~3.318 V (91%).

  • At 6% pack SOC: cell 13 3.143–3.251 V (SOC 6%), others ~3.287–3.314 V (78–87%).

  • This matches the earlier low-SOC logs (~19–23%) where cell 13 was the clear runner (OV ~3.666–3.692 V during charge pulses).

This full-cycle view confirms cell 13 has significantly lower effective capacity (likely 30–50% less than the average, based on SOC divergence). It behaves as a classic "weak/runner" cell:

• Rises fastest on charge at low/mid SOC → triggers OV protection early.

• Drops fastest on discharge → limits usable capacity.

• At sustained high SOC, passive balancing (bleeding high cells) partially aligns voltages, making the delta smaller and shifting apparent "high" status to other cells.

The pack's high historical OV/HV counters (11k+) stem from repeated top-end protections over 739 cycles, exacerbated by this mismatch. SOH 93% indicates overall decent health, but usable Ah is now bottlenecked by cell 13.

I would contact Pylontech for warranty/service (logs show chronic protections).

24 minutes ago, Nexuss said:

After consulting AI here is what its come up with :

Historical counters reveal a chronic issue:

• Bat OV Times: 11,862

• Bat HV Times: 12,932

• Pwr OV/HV Times: high (6,923 / 15,041)

  These indicate thousands of overvoltage events over the battery's life (739 cycles, SOH 93% — still decent capacity).

Key Patterns Across All Logs

• At high SOC (99–100%, Feb 5–6):

  • Cell voltages group reasonably well (ΔV ~0.02–0.15 V during low/no current).

  • Various cells hit High/OV during charge (often cell 11 or 12, e.g., 3.613–3.647 V).

  • Cell 13 frequently appears as the lowest (~3.392–3.465 V in some entries), with individual SOC sometimes lagging at 99% while others are 100%.

  • Frequent OV protections and throttling indicate ongoing passive balancing attempts.

• Transition to deep discharge (Feb 7):

  • As SOC drops below ~90%, cell 13 voltage diverges downward rapidly.

  • By 56% pack SOC: cell 13 ~3.179 V (individual SOC 56%), others ~3.318 V (91%).

  • At 6% pack SOC: cell 13 3.143–3.251 V (SOC 6%), others ~3.287–3.314 V (78–87%).

  • This matches the earlier low-SOC logs (~19–23%) where cell 13 was the clear runner (OV ~3.666–3.692 V during charge pulses).

This full-cycle view confirms cell 13 has significantly lower effective capacity (likely 30–50% less than the average, based on SOC divergence). It behaves as a classic "weak/runner" cell:

• Rises fastest on charge at low/mid SOC → triggers OV protection early.

• Drops fastest on discharge → limits usable capacity.

• At sustained high SOC, passive balancing (bleeding high cells) partially aligns voltages, making the delta smaller and shifting apparent "high" status to other cells.

The pack's high historical OV/HV counters (11k+) stem from repeated top-end protections over 739 cycles, exacerbated by this mismatch. SOH 93% indicates overall decent health, but usable Ah is now bottlenecked by cell 13.

I would contact Pylontech for warranty/service (logs show chronic protections).

Thanks very much for the analysis. I would have never stuck the logs in Ai. That's brilliant use of it.

I'm going to open up a ticket with Segen and get this looked at.

Appreciate the assist.

12 minutes ago, JuliusK said:

Thanks very much for the analysis. I would have never stuck the logs in Ai. That's brilliant use of it.

I'm going to open up a ticket with Segen and get this looked at.

Appreciate the assist.

No problem glad to help! it seems like that cell 13 was weak from the start with that amount of HV errors ... hopefully they honor the warranty . Its also worthwhile to download the logs from the other packs to make sure they are fine . If they wont honor the warranty installing an active balancer could maybe solve the issue, depending on how weak that cell is .

3 hours ago, JuliusK said:

Updated my capacity to 296Ah.

Thanks for the offer. Attached is the events and history log file. History is over 3mb so I had to zip it.

event_20260207091159.txt

.history_20260207091211.zip

Could you post a log for one of the other batteries?

edit, are you using a latest firmware battery as the master?

Edited February 7Feb 7 by Tinbum

4 hours ago, JuliusK said:

I'm going to open up a ticket with Segen and get this looked at.

I think you are really going to struggle to get any warranty for the battery(s) as the log is showing many over-voltages of 54v. The fact that they are limited at 54v is probably that the battery bms has shut off at that voltage.

Regarding current settings- the bms sends those to the inverter to limit them to what the battery can charge or discharge. If I recall it's normally a max of 37A per battery and for charging it tapers down as the battery becomes full. You screen shot shows 148A which ties up correctly. Setting lower values though may help the longevity of the batteries. Regarding SOH- a set of mine, that I do use quite hard, are at 96% but that's after 5 years. The ones that have a lighter usage are at 98%.

Battery capacity setting shouldn't really have any effect on anything. You SOC should be the value from the battery and not any inverter calculation.

19 minutes ago, Tinbum said:

I think you are really going to struggle to get any warranty for the battery(s) as the log is showing many over-voltages of 54v.

The whole reason it is showing all those HV events is because of the weak cell 13 . He as a end user followed normal use procedure with BMS comms working and amps even limited to 90A so there is absolutely no reason they should not honor the warranty . The logs prove it , dropping from 90% to 6% indicated a clear problem and upon investigation the problem was found , it has nothing to do with having the latest firmware or incorrect charge voltage . Feed those logs into AI for yourself and verify if you want . @JuliusK paste the logs for the other 3 batteries as well .

Edited February 7Feb 7 by Nexuss

58 minutes ago, Nexuss said:

The whole reason it is showing all those HV events is because of the weak cell 13 . He as a end user followed normal use procedure with BMS comms working and amps even limited to 90A so there is absolutely no reason they should not honor the warranty . The logs prove it , dropping from 90% to 6% indicated a clear problem and upon investigation the problem was found , it has nothing to do with having the latest firmware or incorrect charge voltage . Feed those logs into AI for yourself and verify if you want . @JuliusK paste the logs for the other 3 batteries as well .

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.

Edited February 7Feb 7 by Tinbum