1 hour ago, Scorp007 said:

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.

That's what pretty much what any decent BMS does.

The Pylontech BMS has done that here but it's voltages are set a bit on the high side- hence the later revised voltages in the latest firmware. Here though if the inverter had been working correctly the voltages would never have got up high enough to require the BMS to physically intervene. It also enables infinite ramping down of voltage / current and not just on/off or limiting to say 10A.

17 hours ago, Tinbum said:

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

What you mention are protective parameters, not charge managing. If any those exceeds critical value by internal cause the BMS has the ability to disconnect itself from the terminals. If you have a bank of several battery packs there is no need to intervene with the inverter leaving the rest of the system functional.

What you need however is periodically monitoring of the packs. I do it with a RS485 bus connected to each pack and wired to a laptop in my office. You might also do it with WiFi.

2 hours ago, Beat said:

What you mention are protective parameters, not charge managing. If any those exceeds critical value by internal cause the BMS has the ability to disconnect itself from the terminals. If you have a bank of several battery packs there is no need to intervene with the inverter leaving the rest of the system functional.

What you need however is periodically monitoring of the packs. I do it with a RS485 bus connected to each pack and wired to a laptop in my office. You might also do it with WiFi.

Wrong they are charge managing parameters.

In your system if a battery overheats it shuts down. The inverter keeps charging at the same current, the next battery overheats and shuts down until they have all shut down.

In a connected system the inverter reduces it's current as the battery warms and the whole system stays up and running.

Unconnected is dangerous. If yours, say you have 2 batteries and you set the inverter current at 2x the batteries max charge current and then a battery bms shuts down you will then be putting 2x the max charge current into 1 battery.

In a connected system inverter will know to reduce the charge current to the max a single battery can take.

Edited February 10Feb 10 by Tinbum

5 hours ago, Tinbum said:

Wrong they are charge managing parameters.

In your system if a battery overheats it shuts down. The inverter keeps charging at the same current, the next battery overheats and shuts down until they have all shut down.

In a connected system the inverter reduces it's current as the battery warms and the whole system stays up and running.

Unconnected is dangerous. If yours, say you have 2 batteries and you set the inverter current at 2x the batteries max charge current and then a battery bms shuts down you will then be putting 2x the max charge current into 1 battery.

In a connected system inverter will know to reduce the charge current to the max a single battery can take.

Quit a horror scenario you fantasy. My solar panels can never deliver so much power that could overheat the batteries with charging. The total nominal 6kW never deliver at the same time thanks to different orientation. The grid charging current is limited to 0.1 C of the batteries. Besides, if one had so many panels to present a risk, he could limit the charging current in the inverter settings.

8 minutes ago, Beat said:

Quit a horror scenario you fantasy. My solar panels can never deliver so much power that could overheat the batteries with charging. The total nominal 6kW never deliver at the same time thanks to different orientation. The grid charging current is limited to 0.1 C of the batteries. Besides, if one had so many panels to present a risk, he could limit the charging current in the inverter settings.

Not a fantasy, reality. Just because your set up can't do it doesn't mean another can't. It's not just overheating batteries it's also applies to batteries that are cold.

Why limit charging current in the inverter, that would apply all the time, and limit your charging for no reason and wasting production? What happens when you have a sunny morning, but have limited the current, and then the afternoon is dull and you don't get enough to recharge you batteries?

This is a public forum and advice should be correct for ANY scenario.

Edited February 10Feb 10 by Tinbum

15 hours ago, Tinbum said:

This is a public forum and advice should be correct for ANY scenario.

Tinbum, you are a genius for imagination of extreme scenarios, that 99.99% of users never experience.

This forum as well as the inverter forum are full of threads complaining about BMS to inverter comms issues. The actual thread is a typical example. The author neglected proper inverter settings assuming the BMS would take care of it. But that didn't happen. I cannot remember any thread with an issue caused by the lack of such comms. I conclude that comms cause more issues than they resolve. One cannot over emphasize the importance of proper inverter settings according to battery specs, with or without comms.

15 hours ago, Tinbum said:

Why limit charging current in the inverter, that would apply all the time, and limit your charging for no reason and wasting production?

Just figure out if there is or is not a risk.

3 hours ago, Beat said:

Tinbum, you are a genius for imagination of extreme scenarios, that 99.99% of users never experience.

This forum as well as the inverter forum are full of threads complaining about BMS to inverter comms issues. The actual thread is a typical example. The author neglected proper inverter settings assuming the BMS would take care of it. But that didn't happen. I cannot remember any thread with an issue caused by the lack of such comms. I conclude that comms cause more issues than they resolve. One cannot over emphasize the importance of proper inverter settings according to battery specs, with or without comms.

Just figure out if there is or is not a risk.

They are not extreme at all, inverter regulation by battery temperature is used all the time.

Forums like this attract people that are having problems and you don't hear about the 10's, 100's, 1000's of thousands that don't have a problem.

Many of the problems on here boil down to bad installers, poor design and probably most of all poor quality inverters.

This thread is nothing to do with the author neglecting proper inverter settings. Read the thread again from the start.

Your advice is bad.

Edited February 11Feb 11 by Tinbum

On 2026/02/11 at 10:08 AM, Beat said:

One cannot over emphasize the importance of proper inverter settings according to battery specs, with or without comms.

This statement being classified "bad advise" any further discussion becomes obsolete. I stop it right here.

1 hour ago, Beat said:

This statement being classified "bad advise" any further discussion becomes obsolete. I stop it right here.

You know quite well I am referring to the advice of not using communication.

Edited February 12Feb 12 by Tinbum

On 2026/02/08 at 1:51 PM, JuliusK said:

I'm going to get the installer involved tomorrow.

To get back on thread how did it go?

18 hours ago, Tinbum said:

To get back on thread how did it go?

Morning, I'm waiting for response from Segen after I submitted my rma paperwork with all the log files from the batteries.

Have you used Solar Diety for any pylontech work? They claim to be the authorised pylontech repair center for South Africa?

6 hours ago, JuliusK said:

Morning, I'm waiting for response from Segen after I submitted my rma paperwork with all the log files from the batteries.

Have you used Solar Diety for any pylontech work? They claim to be the authorised pylontech repair center for South Africa?

I'm pretty certain they will throw it out due to over voltage. What about the installer?

I'm in the UK so no.

Edited February 13Feb 13 by Tinbum

On 2026/02/13 at 1:04 PM, Tinbum said:

I'm pretty certain they will throw it out due to over voltage. What about the installer?

I'm in the UK so no.

The installer is coordinating all of this for me with the supplier.

If they throw this out, then what's my options? If the inverter doesn't listen to the libms, go to Sunsynk?

7 hours ago, JuliusK said:

The installer is coordinating all of this for me with the supplier.

If they throw this out, then what's my options? If the inverter doesn't listen to the libms, go to Sunsynk?

Yes, I think this is an inverter fault that has caused the battery problems. I would probably ask the installer to confirm the settings are ok and get them to actually measure the voltage coming out of the inverter when the inverter thinks it is at 53.2v.

It's a pity you dont seem to have the log files for the batteries from initial installation date. I would check that again in battery view.

5 hours ago, Tinbum said:

Yes, I think this is an inverter fault that has caused the battery problems. I would probably ask the installer to confirm the settings are ok and get them to actually measure the voltage coming out of the inverter when the inverter thinks it is at 53.2v.

It's a pity you dont seem to have the log files for the batteries from initial installation date. I would check that again in battery view.

Thanks for the suggestion, I'm going to get him to test the voltage. I'll check the batteries for older log files too.

On 2026/02/16 at 8:06 PM, JuliusK said:

Thanks for the suggestion, I'm going to get him to test the voltage. I'll check the batteries for older log files too.

What was the eventual outcome here?

On 2026/03/01 at 11:08 AM, I84RiS said:

What was the eventual outcome here?

The battery in question has swollen and Segen / Pylontech are refusing the warranty. Seems like 3/4 batteries have swollen, even though there is communication between the inverter and the batteries. I'm at a loss for words.

A bit more of a complete answer.

I had Segen support connect to the batteries remotely and pull the logs via Battery View, they state because of the over voltage errors and that the batteries have swollen the OEM (Pylontech) will not honor the warranty. My argument was that there were no visible error presented to me at any point in the last 5 years so that I could correct anything. The batteries never went into safe mode, there were no errors logged on the Sunsynk inverter.

They stated that because of one setting that was disabled in the Sunsynk inverter that is why no error were ever logged, the settings in question is "BMS_Err_Stop - When it is active, if the battery BMS failed to communicate with inverter, the inverter will stop working and report fault." Every time I looked at my inverter and it was often, the BMS was working correctly all info was being displayed in the Sunsynk LiBMS screen. Segen's Support then states that the error were transient and because the BMS_Err_Stop was not enabled, the BMS communication issue would clear it's self and I would not see it on the panel. Even though Pylontech battery BMS does have over voltage protection and over charge protection built in?

So essentially 4 Pylontech us3000c batteries down the drain.

I thought that they would reject it.

You really need to try to file a claim against the inverter company.

This thread, and my recent experience with Goodwe SA, lead me to ask what a BMS actually does. Does it not have the ability to protect the battery against overcharging?

My first batteries were Revovs. There was a statement from one of their technicians that I had overcharged. I countered this on various grounds, including that they have a BMS that is supposed to protect their batteries.

More recently Goodwe SA restricted the charge current on my inverter, saying that they were acting in accordance with instructions from the battery manufacturer. They at first assumed for some reason that I was using Pylontechs. When I said, no, it's FreedomWon then they produced a document from that company that instructed them on charge rate settings.

Both those brands of battery have a BMS that they can configure as they see fit. Either they don't trust the BMS to do the job of protecting the batteries, or I don't understand what a BMS does. When that FW LiTE was installed the technician set the Goodwe inverter into "default lithium" mode and plugged the comms cable in. The BMS then took over and set everything. If their BMS can do that, then why are FW asking for hard limits to be imposed on the inverter side (and at least than the 1C their batteries are supposed to be).

The setting they gave me when they thought I had Pylontechs was well below 0.5C. Again, why?

39 minutes ago, Bobster. said:

This thread, and my recent experience with Goodwe SA, lead me to ask what a BMS actually does. Does it not have the ability to protect the battery against overcharging?

My first batteries were Revovs. There was a statement from one of their technicians that I had overcharged. I countered this on various grounds, including that they have a BMS that is supposed to protect their batteries.

More recently Goodwe SA restricted the charge current on my inverter, saying that they were acting in accordance with instructions from the battery manufacturer. They at first assumed for some reason that I was using Pylontechs. When I said, no, it's FreedomWon then they produced a document from that company that instructed them on charge rate settings.

Both those brands of battery have a BMS that they can configure as they see fit. Either they don't trust the BMS to do the job of protecting the batteries, or I don't understand what a BMS does. When that FW LiTE was installed the technician set the Goodwe inverter into "default lithium" mode and plugged the comms cable in. The BMS then took over and set everything. If their BMS can do that, then why are FW asking for hard limits to be imposed on the inverter side (and at least than the 1C their batteries are supposed to be).

The setting they gave me when they thought I had Pylontechs was well below 0.5C. Again, why?

What a BMS should do and what a BMS actually does or what a inverter listens to is a mystery to me.

So like you I understood the BMS to be the mechanism by which the inverter is controlled that then charges or discharges the batteries to the appropriate level. So if something is outside a set of parameters the BMS should prevent the batteries being damaged. But for what ever reason they do not seem to be doing their intended task.

As in my scenario my batteries were being over charged, the Sunsynk inverter charge settings were only ever to be used if the bms was not available. There were 16k over charge logged error on the batteries yet the batteries continued to work, they never went into protected mode not once.