For a shame, I don't focus on HV batteries, so my knowledge is very limited here.

However, there's one thing I can tell you:

On 2024/11/03 at 8:40 AM, PylonHV said:

During Discharge cycle when the SOC reaches 45% the Batt. module which was initially having UnBalanced cell voltages (but later it was balanced by BMS) just drops the SOC from 45% à35% à20% which is the Cut off for the BMS. At this stage its cells voltage also become UnBalanced Again.

In Pylontech HV batteries, all the cells are connected in series. Not just in a pack, but also all the cells within whole battery stack. (The exception is a multi-stack battery spread across multiple rack cabinets).

Based on this, discharging current is the same for each and every cell, regardless of a specific cell's internal resistance and even regardless of length and resistance of the cables. Therefore, it's impossible that a set of cells would be discharged heavier than the others.

So, taking into account the above fact, the quoted behavior tells us, that some cells are having a lower capacity. When a cell has a lower capacity than others in a series, you can still do a perfect "top balancing", but during the discharging phase this cell will experience faster voltage drop.

This is something that you should be able to see in BatteryView - looking at the individual voltages of all the cells simultaneously.

Speaking of SOC calculation when using LiFePO4 chemistry, the BMS has just two ways of figuring SOC here:

• Precise: Counting IN/OUT mAh
• Coarse: Looking for LOW/HIGH Voltage thresholds and declaring that the battery is fully charged, near flat or totally flat.

IMHO, some of the cells are having lower capacity, or even damaged. That's the reason why SOC of the battery drops slowly at first (precise SOC calculation), but once you get to 45% it starts to drop quickly (coarse SOC calculation).

 

BTW: Please create a separate thread for solving problems like these next time. Otherwise the forum will end-up in chaos

 

 

Thanks for the Reply Youda!

The Whole Battery Pack is Connected through Pylontech BMS to the Inverter so there is No chance of misuse.

 

A separate thread will be created next time!

 

Edited November 4, 20241 yr by PylonHV

51 minutes ago, PylonHV said:

Must tell you that before adding the 2 additional Batt. Modules every thing was 100% Normal.

Normally, I would say that the 4 older packs had some wear to is, and that wear was even. Therefore, when they worked together it was invisible and they were discharging gradually. After you added 2 new packs, the overall capacity was increased (and runtime too), but since older packs have a lower capacity (due to being worn) you are not able to discharge battery down to zero. But for just 1 Year of usage, there should be no such effect.

Also, should the above be the case, you would experience a premature SOC drop during discharge even before adding new packs.

Long-story-short: I don't know what's going on here, really.

51 minutes ago, PylonHV said:

As the Whole Battery Pack is used hardly for 1 Year, would Pylontech Provide Warranty for the H48050 Modules?

That's the question for Pylontech to ask.

From my experience:

A] When the reseller has a nice revenue with Pylontech, there's a chance for warranty to work as the Pylontech wants to keep that revenue.

B] Once that's just a small shop that resells AliExpress stock, there's no hope.

C] Direct communication with Pylontech works okay for the firmware updates (sometimes), but definitely does not for the warranty claims.

Edited November 4, 20241 yr by Youda

13 minutes ago, Youda said:

Normally, I would say that the 4 older packs had some wear to is, and that wear was even. Therefore, when they worked together it was invisible and they were discharging gradually. After you added 2 new packs, the overall capacity was increased (and runtime too), but since older packs have a lower capacity (due to being worn) you are not able to discharge battery down to zero. But for just 1 Year of usage, there should be no such effect.

Also, should the above be the case, you would experience a premature SOC drop during discharge even before adding new packs.

Long-story-short: I don't know what's going on here, really.

That's the question for Pylontech to ask.

From my experience:

A] When the reseller has a nice revenue with Pylontech, there's a chance for warranty to work as the Pylontech wants to keep that revenue.

B] Once that's just a small shop that resells AliExpress stock, there's no hope.

C] Direct communication with Pylontech works okay for the firmware updates (sometimes), but definitely does not for the warranty claims.

This is very much like another thread in the battery section where someone else added batteries but I suspect didn't ensure they were equal soc when added. He asked the question then hasn't replied despite reading the thread since!!

 

Edited November 4, 20241 yr by Tinbum

2 minutes ago, Tinbum said:

This is very much like another thread in the battery section where someone else added batteries but I suspect didn't ensure they were equal soc when added. He asked the question then hasn't replied despite reading the thread since!!

Yeah, you're right. Sometimes I assume blindly that the operator did all the logical steps that I would do and then experienced the issue.

Here, the logic tells that one has to get SOC of all the individual modules to the same level, before combining them in a stack.

Not easy with HV batteries, since the new ones are being shipped with approximately 40-50% SOC and you cannot charge them one by one, as they are HV (Most of the HV inverters are unable to work with just one or two packs in series, they need 4 at least).

 

 

 

Thanks for your replies Youda and Tinbum!

Can you kindly share different ways to bring all Batt. Modules at the same level?

As Youda has correctly pointed out that the system requires a minimum of 3 Batt. Modules to start functioning.

Is there any way to Top Balance/Charge 1-Module of Pylontech High Voltage H48050 Separately?

Overall state of Health of Battery Pack and Individual Modules is Excellent.

Looking forward to your valuable inputs.

Thanks

Edited November 4, 20241 yr by PylonHV

@PylonHV,

based on what @Tinbum pointed-out....are you able to bring all the 6 packs to 3,5V per cell when fully charged?

Why:

• 3.5V indicates that a LFP cell is almost 100% charged.
• Contrary, 3.4V can be anyhing from 20 to 80%.

Here I think it depends if the new ones were at a higher or lower soc when added. Depending on which way round I would either discharge or charge and once they had reached the max or min soc remove the new ones and then charge or discharge the old ones until they also reach the same max or min soc. That's if you can't charge each individually with a separate charger.

Edited November 4, 20241 yr by Tinbum

29 minutes ago, Youda said:

Not easy with HV batteries, since the new ones are being shipped with approximately 40-50% SOC

 

 

 

For some reason HV are 100% SOC on delivery according to the manual unless otherwise requested. I find this strange as I would thought transport regs would want less and storage is best at about 30%..

Just now, Tinbum said:

For some reason HV are 100% SOC on delivery according to the manual unless otherwise requested. I find this strange as I would thought transport regs would want less and storage is best at about 30%..

That may not be true, as the voltage of new modules is around 50VDC

7 minutes ago, PylonHV said:

That may not be true, as the voltage of new modules is around 50VDC

I would think they could be very near 100% when at 50v. My LV ones are at 88% and 49.8v at the moment.

As the Battery Packs are Under Warranty, therefore they are only Connected to Pylontech BMS to maintain Warranty.

The BMS has a Linear Charge Curve and Right at the top of the charging curve is where the Imbalance occurs and the batteries are UnBalanced with cell voltages of 3.5V (vs) 3.4V, thus UnBalancing  by more than 100milli Volts.

The BMS then Re-Balances all the Packs to around 3.4V and 3.3V with a State of Charge at 100% (50ah), but the modules which were Un-Balanced at the Top and then Re-Balanced by BMS, these are the Same Modules which Drop the Charge at or Below 45% SOC.

Is it possible to connect a variable voltage Charger to a Individual Battery Module Directly? and would it take charge?
as these are designed differently compared to Low Voltage Batteries. The low voltage ones have their own BMS and Charge level indicators.

Solutions would be Highly Appreciated.

Edited November 4, 20241 yr by PylonHV

3 minutes ago, PylonHV said:

As the Battery Packs are Under Warranty, therefore they are only Connected to Pylontech BMS to maintain Warranty.

The BMS has a Linear Charge Curve and Right at the top of the charging curve is where the Imbalance occurs and the batteries are UnBalanced by more than 100milli Volts.

The BMS then Re-Balances all the Packs to around 3.4V and 3.3V with a State of Charge at 100% (50ah), but the modules which were Un-Balanced at the Top and then Re-Balanced by BMS, these are the Same Modules which Drop the Charge at or Below 45% SOC.

Is it possible to connect a variable voltage Charger to a Individual Battery Module Directly? and would it take charge?
as these are designed differently compared to Low Voltage Batteries. The low voltage ones have their own BMS and Charge level indicators which is Not the case with High Voltage Modules.

Solutions would be Highly Appreciated.

I know HV and LV are different but the cells are the same and i believe both are 15 cell.

 

to your question

The HV will have a BMS in each pack.

11 minutes ago, Tinbum said:

The HV will have a BMS in each pack.

Thanks for the info!

Yes you are correct, each module has 15 cells.

Can you kindly inform if an external charger is connected to Individual Batt. Module, how to monitor individual Cell Voltage, so that None of the Cells are Charged above 3.5V to 3.6V?

Cells can be monitored with Battery View, however that works when a Minimum of 3 Modules are connected.

Looking forward,

 

Edited November 4, 20241 yr by PylonHV

Well, each H48050 is able to work standalone and you can monitor it via it's RS232 console port.

Even now, when you have H48050 in the stack, you can plug a console cable into an individual brick.

 

On the other hand - charging 50Ah pack with a bench power supply running for days at 3Amps is not an easy task. Do you have enough experience with that?

If you do, go on. If not, just ask hire somebody experienced to come onsite and do this for you.

 

You don't want ruin batteries that are almost new...and/or kill yourself in the process.

Edited November 4, 20241 yr by Youda
strikethrough

43 minutes ago, Youda said:

Well, each H48050 is able to work standalone and you can monitor it via it's RS232 console port.

Even now, when you have H48050 in the stack, you can plug a console cable into an individual brick.

 

On the other hand - charging 50Ah pack with a bench power supply running for days at 3Amps is not an easy task. Do you have enough experience with that?

If you do, go on. If not, just ask hire somebody experienced to come onsite and do this for you.

 

You don't want ruin batteries that are almost new...and/or kill yourself in the process.

Youda thanks for the reply!

Yes each brick has individual RS232 Port, in fact we have connected to the individual H48050 Batt. Module using Console cable, but the brick was connected to the BMS during this time.

The earlier pictures of the Modules voltages were from BMS RS232 port.

The issue was that if individual Battery Module is removed from the String, then RS232 connection does Not work? or may be we are missing something here?

Do you need to be connected to the variable voltage charger for the RS232 port to work on individual Brick?

Also the idea is to charge 3 Batt. modules/bricks in a string through the Solar Inverter up to 95%-97% SOC, at this time remove the individual Batt. Module of H48050 and connect to a Variable Voltage DC Power Supply which is set to 52.5VDC with a charging current between 0.5A to 0.75A and wait for all the cells to come up to 3.5V.

If we can be successful in bringing 45Cells of the 3 Batt packs to 3.5V each, then we can try to connect again to the inverter and see the results.

The only thing bothering here is as How to monitor the cells during this trickle charge?

if it is possible for each unit of H48050 to provide cell voltages through Console cable /RS232 withOut BMS in the picture that would make our task much easy.

Looking forward to your opinion.

Edited November 4, 20241 yr by PylonHV

H48050 provides/accepts voltage on it's terminals even if it's not "running".

In other words, even if STATUS LED is OFF, you can still charge/discharge the individual pack.

As for the RS232 port on the individual H48050 to work, the STATUS LED must be ON (Hint: it does not matter whether it will be RED or GREEN).

How you will light up the LED is up to you. There are ways, all of them quite risky.

 

IMHO, hire someone who did this before. You're not the first one to have this kind of issue when adding H48050 packs.

 

Thanks for the reply Youda!

 

Edited November 5, 20241 yr by PylonHV

16 hours ago, Tinbum said:

I know HV and LV are different but the cells are the same and i believe both are 15 cell.

 

to your question

 

Tinbum thanks for sharing this picture where Pylontech recommends to charge the modules to 100%SOC before connecting.

The question here is What is the Best/Safe way to Charge "Single Module" of H48050 High Voltage Batt.?

if the module is connected to Trickle Charger/Variable Voltage DC Charger set at 3.5V per cell (52.5V for 15 cells) at a charging current of 0.5Amps, would this method safely bring all the 15 cells to 3.5V? in a simple way if one of the cell reaches the required 3.5V before other cells, would this cell stop taking charge of 0.5A? or would it continue to take charge as there is NO external Active Balancer in this situation?

Would this method be good enough to bring all the cells to 3.5V without any cell getting above this voltage, in another way, would this method work to balance out all the 15 cells of the module?

Pylontech in their manual have not mentioned or explained how to balance charge individual Batt. Module to 100% state of charge.

Kindly elaborate and if possible provide applicable solution

Thanks.

Edited November 5, 20241 yr by PylonHV

7 hours ago, PylonHV said:

 

Tinbum thanks for sharing this picture where Pylontech recommends to charge the modules to 100%SOC before connecting.

The question here is What is the Best/Safe way to Charge "Single Module" of H48050 High Voltage Batt.?

if the module is connected to Trickle Charger/Variable Voltage DC Charger set at 3.5V per cell (52.5V for 15 cells) at a charging current of 0.5Amps, would this method safely bring all the 15 cells to 3.5V? in a simple way if one of the cell reaches the required 3.5V before other cells, would this cell stop taking charge of 0.5A? or would it continue to take charge as there is NO external Active Balancer in this situation?

Would this method be good enough to bring all the cells to 3.5V without any cell getting above this voltage, in another way, would this method work to balance out all the 15 cells of the module?

Pylontech in their manual have not mentioned or explained how to balance charge individual Batt. Module to 100% state of charge.

Kindly elaborate and if possible provide applicable solution

Thanks.

I'd refer you back to what @Youda said above.

My thinking would be the following but this is just going on educated guesswork;

Each battery block will have it's own bms to look after its cells. I would expect this to incorporate safety features to protect the battery from over-voltage, cell over-voltage, temperature, etc  and it will manage the balancing of the cells. This bms will also have the facility to allow current to flow through the battery (not the cells) at 100% SOC to enable all the battery packs to equalize their SOC at 100% with each other. This current will probably on be small, could well be something like 1A as shown in that other thread I linked to.

I would have thought connecting a charger up to an individual battery at 52.5v would be fine and not result in any cell over-voltage as the bms would cut in. This is the same as the battery being used in service except their is no inter battery /master bms communication. If the battery will accept charge like this then this would seem to point that it was ok as otherwise Pylontech would have set the battery to isolate on lack of an inter battery communication fault.

If I had a HV system I would be looking at what info was passed in the messages between the packs and asking Pylontech for the protocol.

BUT - I would contact Pylontech and ask them.

 

 

Edited November 5, 20241 yr by Tinbum

Thanks Tinbum for the reply,

Actually if the main BMS was that efficient, it would balance the individual cells to around 3.5V.

If we take the example of individual cells, the problem starts when one of the cells reaches or crosses 3.5V, the BMS continues to supply this cell (instead of cutting it off) while the lagging cell can be at 3.4V. Ideally the BMS should supply the lagging cell to bring it up to the leading cell, instead the cut off for the leading cell is set at 3.6V and that is where the mismatch is created and Top End Balancing is Not Properly Performed by the main BMS or the BMU of the individual module (Not sure which one is it?).

Finally the BMS Balances all the cells to around 3.4V, but during discharge the same module which had around 100milliVolt difference at top end will drop the charge.

The whole idea of charging individual Module is so that all the cells can settle at 3.5V, how to perform this task safely and efficiently is any one's guess?

As you had Access to the Pylontech Manual where they mention to fully charge the Battery, is there any way (published or otherwise) to know exactly what do they Technically Mean by this?

 

43 minutes ago, PylonHV said:

Thanks Tinbum for the reply,

Actually if the main BMS was that efficient, it would balance the individual cells to around 3.5V.

If we take the example of individual cells, the problem starts when one of the cells reaches or crosses 3.5V, the BMS continues to supply this cell (instead of cutting it off) while the lagging cell can be at 3.4V. Ideally the BMS should supply the lagging cell to bring it up to the leading cell, instead the cut off for the leading cell is set at 3.6V and that is where the mismatch is created and Top End Balancing is Not Properly Performed by the main BMS or the BMU of the individual module (Not sure which one is it?).

Finally the BMS Balances all the cells to around 3.4V, but during discharge the same module which had around 100milliVolt difference at top end will drop the charge.

The whole idea of charging individual Module is so that all the cells can settle at 3.5V, how to perform this task safely and efficiently is any one's guess?

As you had Access to the Pylontech Manual where they mention to fully charge the Battery, is there any way (published or otherwise) to know exactly what do they Technically Mean by this?

 

The manual was just one I found online using Google. You will have to ask Pylontech. I only have LV batteries so can't test.

If the cells are the same as the LV, which I'm sure they will be, then they have a charge voltage 53.2v set by the bms, that would be 3.546v per cell. The LV batteries cell balance at anything over 30ma imbalance, if I remember correctly, but the actual balance current is very small, miliamps. It can therefore take a long time for cell voltages to balance. I doubt very much that the main bms will have anything to do with cell balancing- that will be left to the internal battery bms.

I'm pretty certain the HV battery will be pretty well the same as the LV but the BMS will just have the facility to cope with passing a small amount of current through it to enable the other series batteries to charge when its cells are full. I'm also pretty sure that if you leave all your batteries connected and they have an imbalance they will eventually equalize but it could take a very long time.

Again, I would ask Pylontech, I can't give you an answer as I don't know it..

2 hours ago, Tinbum said:

The manual was just one I found online using Google. You will have to ask Pylontech. I only have LV batteries so can't test.

If the cells are the same as the LV, which I'm sure they will be, then they have a charge voltage 53.2v set by the bms, that would be 3.546v per cell. The LV batteries cell balance at anything over 30ma imbalance, if I remember correctly, but the actual balance current is very small, miliamps. It can therefore take a long time for cell voltages to balance. I doubt very much that the main bms will have anything to do with cell balancing- that will be left to the internal battery bms.

I'm pretty certain the HV battery will be pretty well the same as the LV but the BMS will just have the facility to cope with passing a small amount of current through it to enable the other series batteries to charge when its cells are full. I'm also pretty sure that if you leave all your batteries connected and they have an imbalance they will eventually equalize but it could take a very long time.

Again, I would ask Pylontech, I can't give you an answer as I don't know it..

Thanks again!

When you say a very long time for cell voltages to balance, can you define any ball park figure i.e. Days, Month or even a Year?

Here again a question comes to mind (having seen the behavior of Pylontech Balancing algorithm), during every charging cycle (if example of individual module is taken) the top end voltages of the cell cross above 3.5V but the bms does not cut off the current till the higher cell reaches 3.6V while the lowest voltage cell also reaches 3.5V, at this point the voltage delta can be 100milliVolts. The balancing is performed afterwards bringing the voltages close to 3.4V. Technically BMS/BMU balances the cells with every charge cycle, however during Discharge the Module which had imbalance at the top are exposed, as these modules drop charge at around 50%.
Why doesn't the BMS cuts power to the highest voltage cell while at the same time charging the lower voltage cell to come upto 3.5V? so that 15cells of the module can be balanced at around 3.5V

You must be right in assuming that both HV & LV would be similar, therefore you have seen the behavior of LV cells and balancing.
It is pertinent to ask you here that if an external Variable Voltage DC power supply is set at 52.5V (3.5V per cell), would it be able to restrict the higher cells to stop taking charge/increase their voltage once they reach 3.5V and at the same time force the lower voltage cells to come upto 3.5V so that all the cells happily live at 3.5V?

any ideas?

 

 

Edited November 5, 20241 yr by PylonHV

One more thing to ask,

Is there any beneficial effect of connecting 2 modules/bricks in parallel to each other (as can be done for Low Voltage Batt.) for Balancing of Cell Voltages?

The goal would be to bring all cells to 3.5V

Thanks