Author

Hey everyone.

I have a US3000, and 3x US2000's.  They are connected in parallel, with the comms cables connected to a Pi with Solar Assistant.  Load connected to two Axpert 5kVA inverters via busbar.

They usually charge to 100% by around 1pm - 2pm when I am not using anything with very heavy loads during the day (tumble drier, vacuuming the place, aircon etc.)

Suddenly, a week or two ago, I noticed that they only charge to 85% even though there is still a lot of sun available, and, once they reach the 85% the incoming solar KW also drops to match the rest-of-the-house usage load.

Upon investigation (in Solar Assistant, and physically checking the led's of the batteries), I discovered that one of the US2000's is only charged to 33%, while the others are at 100%. 

So, now I pose the question:  to balance or not to balance?

I have seen multiple videos indicating that you connect them in parallel, while disconnecting all other comms, and from power....and then press the start-stop button so that they balance each other.

Then I have seen comments saying that is not right, and other comments confirming it is right, and other comments saying the Master takes control of all batteries always, andyou should not be concerned about balancing, and so it goes from one side to the other etc etc etc.

Oh, and I have emailed Pylontech directly, last Friday.  No response as yet.

So, could anyone advise?  How do I get that one US2000 to charge fully, like the others?  Do I "balance", or not?  If not, what is my next step?  It's been at least a week-and-a-half and that battery continues to NOT charge up.

Advice always appreciated.

Cheers all

Edited November 27, 2024Nov 27 by Riaan Eloff

There is no point in "balancing" - the fact that they are connected in parallel means that they are all already at the same voltage.  The balancing you read about is what is done when adding new batteries to your stack.  (To add to the confusion, there is also cell balancing, but that is handled by the internal balancer)

You could get Batteryview and connect to the console port of the dud battery.  You will likely see that there is one cell that is stuck at 33% charge (the Pylontech reports the SOC of the battery as that of the lowest cell, not the average).

Irrespective of what you learn from Batteryview, your next step should probably be to remove the bad battery and send it back to your supplier, hopefully for a warranty claim (assuming it is still covered).

Once a battery has a bad cell there is very little that can be done - the pouch cells in these batteries are not readily available, and even if they were replacing them is not a trivial task.

I've a similar setup, balancing might help but also think one cell is faulty. You can however try switching all off,  doing balancing and then all back on.

 

I see some US2000 plus models on Facebook marketplace, might be the best, easiest and cheapest to replace the battery with another one with similar cycles.

Batteryview is best to see what is going on.

Do they regularly get charged to 100% SOC? If not then do that first.

Edited November 27, 2024Nov 27 by Tinbum

Thanks for the replies folks.  Much appreciated.

I am going to get batteryview, and try that next.

To answer some questions:

They do get charged to 100% almost daily.  Only on the days that we use heavy loads (like maybe washing day - 2x per week - washing machine and tumble drier and iron being used during the day - thus, using a lot of energy, and not filling batteries to 100%) do they NOT always go to 100%, but, at least every Saturday and Sunday, the fully charge up, and then probably more than on additional day per week.

In terms of firmware:  I just spoke to Sengensolar (A South African supplier of Pylontech).  They say that they may need to update the firmware.  They did indicate also that my unit (based off the serial number) was not purchased via them, but,. they can service it - not replace/credit, though.

Now, I can understand if firmware is out of date, BUT, what concerns me is:  This battery has been operating in this pack for either 1 year, or 2 years.  I don't recall off the top of my head whether I installed the latest (US3000) a year ago, or two years.  But, fact is, they've been together for a while.  The issue "suddenly" started a few weeks ago.  Thus I'm not sure I'm convinced about firmware.

Lastly, can anyone assist with who would be the correct Pylontech supplier, where I could go with the battery if needed?  The installer that did the system for me "disappeared" a few years later.  They are still functioning, but they liquidated their company, and started operating under a new name.  So now they are not at all eager to assist me.

As you have been taking them regularly to 100% SOC it points to a faulty battery.

You could contact pylontech directly and I'm pretty sure they would sort a dealer/supplier out.

On 2024/11/27 at 3:45 PM, Riaan Eloff said:

Author

Hey everyone.

I have a US3000, and 3x US2000's.  They are connected in parallel, with the comms cables connected to a Pi with Solar Assistant.  Load connected to two Axpert 5kVA inverters via busbar.

They usually charge to 100% by around 1pm - 2pm when I am not using anything with very heavy loads during the day (tumble drier, vacuuming the place, aircon etc.)

Suddenly, a week or two ago, I noticed that they only charge to 85% even though there is still a lot of sun available, and, once they reach the 85% the incoming solar KW also drops to match the rest-of-the-house usage load.

Upon investigation (in Solar Assistant, and physically checking the led's of the batteries), I discovered that one of the US2000's is only charged to 33%, while the others are at 100%. 

So, now I pose the question:  to balance or not to balance?

I have seen multiple videos indicating that you connect them in parallel, while disconnecting all other comms, and from power....and then press the start-stop button so that they balance each other.

Then I have seen comments saying that is not right, and other comments confirming it is right, and other comments saying the Master takes control of all batteries always, andyou should not be concerned about balancing, and so it goes from one side to the other etc etc etc.

Oh, and I have emailed Pylontech directly, last Friday.  No response as yet.

So, could anyone advise?  How do I get that one US2000 to charge fully, like the others?  Do I "balance", or not?  If not, what is my next step?  It's been at least a week-and-a-half and that battery continues to NOT charge up.

Advice always appreciated.

Cheers all

You might also want to check for signs of the cells swelling. What did you configure your max charge rate to be?

Thanks for the replies folks.

I actually was able to get a response from the original installer.  They did offer to assist.

I checked that physical battery, and there was clear signs of swelling, so my assumption is that it is a faulty batter.

Date of manufacture on the battery is listed as 2020 (I think April/May), so I'm rather sure Pylontech will honour the wanrranty, let's see.

The installer collected the battery from me this week Tuesday, so I await info, hopefully soon.

Cheers all

Hi Riaan - what is your charging voltage on these pylontechs?

 

On 2024/12/06 at 2:55 PM, Marius2001 said:

Hi Riaan - what is your charging voltage on these pylontechs?

 

Hi Marius,

Float is 53.2V
Max (back to battery) is 52V

Interesting. I have an Axpert 8kW connected to four PylonTech UP5000s. One of the batteries started to do the same thing ie not at 100% while the other batteries were all at 100%. When I took the suspect battery out, it was swollen. I took it to the supplier who pulled the log, there were multiple OverVoltage errors in the log so warranty repair was refused. The log file from the swollen battery is attached, for info.

The concern is that the battery type is set to Pylontech, which in turn automatically sets:

02 Max charging current - 150A

26 Bulk charging voltage - 53.2V

27 Floating charging voltage - 53.2V

29 Low DC cutoff voltage - 45.0V

and those appear to be within the Pylontech recommended ranges. So why were the batteries overchanged? Is this an Axpert issue?

 

Event.txt

3 hours ago, SteveD said:

and those appear to be within the Pylontech recommended ranges. So why were the batteries overchanged? Is this an Axpert issue?

It seems to me that both Pylontech and Voltronics are to blame.  Pylontech for requesting voltages that are too high (in the real world, where 2nd rate manufacturers implement poor control algorithms that overshoot) and Voltronics for being such a 2nd rate inverter manufacturer.

 

3 hours ago, SteveD said:

One of the batteries started to do the same thing ie not at 100% while the other batteries were all at 100%.

You will probably find the other batteries are all in advanced stages of degradation.  Consider setting battery type to USE and max charge voltage to the lowest that still gets you to 100% - my Pylons work well at 52.6V.

Also consider setting the float voltage down to about 50.5V.  It will mean that your SOC will drop to about 99.5% as soon as the batteries are full, but it will greatly enhance their lifespan.

Of course using an Axpert means that your inverter cannot be relied on to correctly switch to float, unless you are running a version of @Coulomb's patched firmware.

6 hours ago, SteveD said:

So why were the batteries overchanged? Is this an Axpert issue?
 

This seems to be a very common occurrence with quite a few inverters and is often mentioned on here.

On 2024/12/12 at 6:49 AM, SteveD said:

Interesting. I have an Axpert 8kW connected to four PylonTech UP5000s. One of the batteries started to do the same thing ie not at 100% while the other batteries were all at 100%. When I took the suspect battery out, it was swollen. I took it to the supplier who pulled the log, there were multiple OverVoltage errors in the log so warranty repair was refused. The log file from the swollen battery is attached, for info.

The concern is that the battery type is set to Pylontech, which in turn automatically sets:

02 Max charging current - 150A

26 Bulk charging voltage - 53.2V

27 Floating charging voltage - 53.2V

29 Low DC cutoff voltage - 45.0V

and those appear to be within the Pylontech recommended ranges. So why were the batteries overchanged? Is this an Axpert issue?

 

Event.txt 983.75 kB · 6 downloads

If you look at the event log you will notice that the there are a number of overvoltage alarms where the highest cell voltage is above 3650mV while the lowest is around 3400mV (at the same time). One should also question how the BMS allows a cell to reach 3834mV.

There are also a number of items on the event log where the lowest cell voltage is around 3000mV while the highest cell voltages 3250mV (at the same time).

Unfortunately the data does not indicate which cell or cells is/are overvolting

Not to sure what the pack overvoltage level is on these batteries but highest pack voltage per the data was 53.295V which seems ok ? (so the overvoltage is/was not caused by a pack over voltage but rather a cell overvoltage event)

My take on this data is that there is /was likely a runner cell in this pack causing the overvoltage alarms (ie there is/was one or more weaker cells compared to the others that would reach 3650mV on charge well before the other cells and 3000mV under load also well before the other cells). If you have a runner cell your charge voltage (on your inverter) really becomes irrelevant to control this (unless you charge a very low voltages).

Unfortunately (for you) and fortunately (for Pylontech) you have no way to proof that this was the case from the start. But, given that there is only 391 cycles (does this look correct given the 6272 OV times) on this battery it is more likely than not that when you purchased this batery that this was indeed the case.

I think they are taking you for a ride and hiding behind their T&C. Unfortunately runner cell are part and parcel of pre packaged battery packs with integrated BMSes and should actually be treated as latent defects.

4 minutes ago, I84RiS said:

If you look at the event log you will notice that the there are a number of overvoltage alarms where the highest cell voltage is above 3650mV while the lowest is around 3400mV (at the same time). One should also question how the BMS allows a cell to reach 3834mV.

There are also a number of items on the event log where the lowest cell voltage is around 3000mV while the highest cell voltages 3250mV (at the same time).

Unfortunately the data does not indicate which cell or cells is/are overvolting

Not to sure what the pack overvoltage level is on these batteries but highest pack voltage per the data was 53.295V which seems ok ? (so the overvoltage is/was not caused by a pack over voltage but rather a cell overvoltage event)

My take on this data is that there is /was likely a runner cell in this pack causing the overvoltage alarms (ie there is/was one or more weaker cells compared to the others that would reach 3650mV on charge well before the other cells and 3000mV under load also well before the other cells). If you have a runner cell your charge voltage (on your inverter) really becomes irrelevant to control this (unless you charge a very low voltages).

Unfortunately (for you) and fortunately (for Pylontech) you have no way to proof that this was the case from the start. But, given that there is only 391 cycles (does this look correct given the 6272 OV times) on this battery it is more likely than not that when you purchased this batery that this was indeed the case.

I think they are taking you for a ride and hiding behind their T&C. Unfortunately runner cell are part and parcel of pre packaged battery packs with integrated BMSes and should actually be treated as latent defects.

Pylontech are actually very good at replacing batteries if the battery is at fault.

4 hours ago, Tinbum said:

Pylontech are actually very good at replacing batteries if the battery is at fault.

The point I was trying to make is that there were no pack overvoltage events in that log, meaning that the batteries were not charged at a to high a voltage.  The only conclusion that I can come to is that battery (or a specific cell) was indeed at fault. 

@SteveD perhaps you should speak to Pylontec directly (or whomever holds the contract to honour this is SA) as opposed to the supplier

5 minutes ago, I84RiS said:

The point I was trying to make is that there were no pack overvoltage events in that log, meaning that the batteries were not charged at a to high a voltage.  The only conclusion that I can come to is that battery (or a specific cell) was indeed at fault. 

@SteveD perhaps you should speak to Pylontec directly (or whomever holds the contract to honour this is SA) as opposed to the supplier

Yes I totally agree. Your post seemed to sugest pylontech would try to get out of it. Often the supplier does, but if you go direct to pylontech they often instruct the supplier to replace them.

2 hours ago, I84RiS said:

were no pack overvoltage events in that log

Correct. The log covers only the last month or so.

However, see the totals at the beginning (from the STAT command)

Pwr OV Times    :       46

(In Pylon speak, a PWR is what we call a battery pack (15 cells) and a BAT is a cell)

Pack OV is at 54V for these batteries.

Edited December 13, 2024Dec 13 by Calvin

I'll just post my recommended Pylontech battery settings, for those not having the BMS control the charge via the BMS to inverter BMS port cable. It's in dire need of redoing, but the important numbers are there: 52.5 and 51.8V.

These figures are a little higher than I use myself when adjusted for 16S (Pylontech is 15S), but were a consesnsus amongst actual Pylontech users. 

Edit: The maximum current setting is for the original 2.4kWh models. Adjust accordingly for recent models' total capacity. 

Edited December 14, 2024Dec 14 by Coulomb

On 2024/12/06 at 2:24 PM, Riaan Eloff said:

Thanks for the replies folks.

I actually was able to get a response from the original installer.  They did offer to assist.

I checked that physical battery, and there was clear signs of swelling, so my assumption is that it is a faulty batter.

Date of manufacture on the battery is listed as 2020 (I think April/May), so I'm rather sure Pylontech will honour the wanrranty, let's see.

The installer collected the battery from me this week Tuesday, so I await info, hopefully soon.

Cheers all

What was the outcome of this?

In my case, I changed the settings to those recommended by Coulomb, bought a new battery and wrote it down to the cost of experience. When the time comes to replace my inverter, I will not use an Axpert again, this should not have happened.

On 2024/12/27 at 9:10 AM, I84RiS said:

What was the outcome of this?

So the company (CNBM in Centurion) reported overcharging as the issue.  The provided (after requests) a full report explaining the overcharge.  I then asked them how is it possible for a unit that has a BMS to become overcharged.  They did not repsond.  I asked again, they just sent me the report.  I asked again, then they responded with:

 

Quote

Hi Riaan

 

Please note that even though the unit has a BMS (Battery Management System). 

 

When a battery receives more electrical charge than it can safely store, it can become overcharged. This is typically caused by issues with the charging system, such as a malfunctioning alternator with a defective voltage regulator, leaving the battery connected to a charger for too long, or using an incorrect charging setting (Parameters) that delivers too much voltage as stated in the report. Essentially, any situation where the charging process is not properly monitored and controlled to stop at the appropriate voltage level can lead to overcharging.

Thus, the logs we receive from the battery can show if it is the battery manufacture fault or end user based fault.

Hence, in this case it has been noted that the overcharged was a result of end user based fault.

If you have any further questions and enquiries, feel free to escalate this issue to pylontech for further clarification. 

Kind regards

Aftersales

I replied asking:
 

Quote

Do I understand correctly:  Even though there is a BMS in the battery, that DOES NOT protect it from possible overcharge?

 

They did not respond.

After a day or so, I repeated my question.  They CC'd me in a mail to Chris (at Pylontech China).  They said:

Quote

Hi Chris 

 

Could you advise the client on the enquiry below. 

 

He wants clarity regarding his overcharged battery, we have also sent him a report.

 

King regards 

Aftersales 

I have not heard back yet.  Interesting fact, though:  they are giving Chris the wrong information.  I did not ask for clarity on the overcharging.  I received their quote, and said that I understand that it was overcharged.  I then asked HOW could it overcharge if it has a BMS.  They said "it can", I finally asked:  Do I understand correctly:  The BMS does NOT protect the battery from overcharging.  THAT was my final, unanswered question.  So, Chris has the wrong info, and I'm going to have to go through the whole conversation AGAIN with him, but, anyways....that's where I'm at presently.

 

Their CC to Chris was four days ago, so, I expect I will probably hear from him in the next few days.

On 2024/12/02 at 2:22 PM, HendrikBigChief said:

You might also want to check for signs of the cells swelling. What did you configure your max charge rate to be?

Just to reply:  I do not have any max charge rate setting.  I do see a max charge current.  Now, these may be the same thing, and I'm just too much of a noob and too uninformed to realize that 🙂 But, ya, I have a max charge current which is 60A

In terms of the cells swelling, yes, that battery that caused the problem was swelling.  You may already have seen the rest of this thread 🙂 

 

Hi @Riaan Eloff

 

6 hours ago, Riaan Eloff said:

Do I understand correctly:  Even though there is a BMS in the battery, that DOES NOT protect it from possible overcharge?

Yes, it does not.

Pylontech's BMS has very limited protection capabilities against overcharge of this type - voltage spikes caused by AC loads and PV power fluctuations that are routed by the inverter to the battery. It can protect the battery against trying to charge it to 56V (for example) with a constant energy flow, but not against the spikes.

Normally Pylontech BMS relies on the active communication with the charger (inverter in this case). Once the BMS sees that cells are almost full, it asks the inverter to lower the charging current. Similarly, when BMS sees Cell High Voltage, it generates High Voltage warning event and the inverter is supposed to stop the charging so the internal balancers can solve the Cell High Voltage issue. Cell Over Voltage Event is even higher level.

For a shame, many inverters are not listening to the BMS requests and events correctly, nor they act as being asked. Axpert(s) being one of them.

 

6 hours ago, Riaan Eloff said:

Hence, in this case it has been noted that the overcharged was a result of end user based fault.

Not really. The damage was a result of what the original installer did and configured.

Following manuals and specsheets blindly is one thing, having enough experience to know what are you really doing is completely another thing.

 

On 2024/12/10 at 9:52 AM, Riaan Eloff said:

Hi Marius,

Float is 53.2V
Max (back to battery) is 52V

Float voltage too high.

This is something what installer should know and set correctly, based on the actual experience with Pylontechs + Axperts.

 

On 2024/12/14 at 3:30 AM, Coulomb said:

I'll just post my recommended Pylontech battery settings, for those not having the BMS control the charge via the BMS to inverter BMS port cable. It's in dire need of redoing, but the important numbers are there: 52.5 and 51.8V.

These figures are a little higher than I use myself when adjusted for 16S (Pylontech is 15S), but were a consesnsus amongst actual Pylontech users. 

Edit: The maximum current setting is for the original 2.4kWh models. Adjust accordingly for recent models' total capacity. 

If you want to minimize further damage, set your inverter according to what @Coulomb says above.

That swollen US2000 battery is K.O., but if you are going to replace it with a new one, it definitely makes sense to prevent the same damage to happen again.

 

 

BTW: If you want to know more about the Pylontech US batteries, just check some posts my thread here:

 

 

 

Hi @Youda

Thank you very much for your response.  I do appreciate.

Yes, I realized this past week, that I will have to adapt my settings to @Coulomb's recommendations.

I did hear back from Chris today.  He did respond with a very good explanation, similar to what you said, although he did not specifically make any reference to inverters or to Axpert (I believe he may not want to have it appear as-if he's playing a "blame game", which I appreciate and respect).  What you are saying, and what he emailed me most definitely point to the need for me to adapt the settings on my system.