Hello everyone,

Has anyone noticed how Luxpower SNA 5000 does not have settings to limit PV charge to the batteries?

With PV Power, the inverter charges the battery to 100% resulting in multiple over voltage protection (OVP) warnings on the BMS and Battery High Voltage warning on the inverter. I thought it will use AC or Generator charge settings for PV charge but nope.

Is there a method to limit the PV charge? I want to use the battery for loadshedding only. This issue is forcing me to discharge the battery over night to avoid filling them quickly in the morning, which avoids multiple OVP warnings on the BMS. I am using an SVolt 5.09KWh 48V battery with comms working via CAN port.

This is frustrating, and shocking how this manufacture did not consider putting settings to control PV charging.

 

Edited September 30, 20232 yr by MightyDee

Thats not an inverter issue its a battery /BMS issue. If you are hitting OVP at less than 55V you have a very unbalanced battery.What battery do you have ?

Edited September 30, 20232 yr by Nexuss

 

Hello everyone,

Has anyone noticed how Luxpower SNA 5000 does not have settings to limit PV charge to the batteries?

With PV Power, the inverter charges the battery to 100% resulting in multiple over charge voltage (OVP) warnings on the BMS and Battery High Voltage warning on the inverter. I thought it will use AC or Generator charge settings for PV charge but nope.

Is there a method to limit the PV charge? I want to use the battery for loadshedding only. This issue is forcing me to discharge the battery over night to avoid filling them quickly in the morning, which avoids multiple OVP warnings on the BMS.

This is frustrating and shocking, how this manufacture did not consider putting settings to control PV charging.

 

As @Nexuss indicated. What battery are you using?

We generally prefer to use PV charging as it is free instead of genny or grid which is costly. 

Get the comms between inverter and battery attended to. The inverter only charges via PV when the BMS is instructing the inverter to do so. Nothing wrong with the Luxpower inverter. Settings at fault. 

 

Hello everyone,

Has anyone noticed how Luxpower SNA 5000 does not have settings to limit PV charge to the batteries?

With PV Power, the inverter charges the battery to 100% resulting in multiple over charge voltage (OVP) warnings on the BMS and Battery High Voltage warning on the inverter. I thought it will use AC or Generator charge settings for PV charge but nope.

Is there a method to limit the PV charge? I want to use the battery for loadshedding only. This issue is forcing me to discharge the battery over night to avoid filling them quickly in the morning, which avoids multiple OVP warnings on the BMS.

This is frustrating and shocking, how this manufacture did not consider putting settings to control PV charging.

The inverter is probably trying to detect the voltage of the battery pack via the terminals it is connected to. The BMS is trying to do the same, but obviously the two don't agree. 

Can you put a comms cable between the BMS and the inverter. This is what I have, and it means that the sort of discrepancies I refer to above can't happen: The BMS tells the inverter what it wants.

Thinking about it, this is the way it should be. With any other setup you risk a two versions of the truth scenario. 

I remember the installation of my battery. All the battery related settings on the inverter were set to default. The cable was plugged in and the BMS took over and set everything the way it wants it. 

The battery is an SVolt 5.09KWh 48V

 

Thats not an inverter issue its a battery /BMS issue. If you are hitting OVP at less than 55V you have a very unbalanced battery.What battery do you have ?

 

 

As @Nexuss indicated. What battery are you using?

We generally prefer to use PV charging as it is free instead of genny or grid which is costly. 

Get the comms between inverter and battery attended to. The inverter only charges via PV when the BMS is instructing the inverter to do so. Nothing wrong with the Luxpower inverter. Settings at fault. 

The comms are working via CAN port, and I have set the Battery brand/protocol to Polyntech (option 2). Yes OVP occurs when the voltage is about 52.9V which is way below the 55V.

 

 

The comms are working via CAN port, and I have set the Battery brand/protocol to Polyntech (option 2). Yes OVP occurs when the voltage is about 52.9V which is way below the 55V.

I don't know the Pylontec profile but my memory is telling me that 55V is too high. Pylon normally have 15 cells. Does the SVolt also have only 15 cells?

 

I don't know the Pylontec profile but my memory is telling me that 55V is too high. Pylon normally have 15 cells. Does the SVolt also have only 15 cells?

Yes the battery is 15 Cells, my voltage normally ranges between 49V to 52.7, when full. I get warnings around this. 51.5V is actually 91% SOC. I am thinking of trying other battery brands and see if this occurs. I would have also prefer in charging my battery up to 85% max.

 

Yes the battery is 15 Cells, my voltage normally ranges between 49V to 52.7, when full. I get warnings around this. 51.5V is actually 91% SOC. I am thinking of trying other battery brands and see if this occurs. I would have also prefer in charging my battery up to 85% max.

Your battery is not happy , the cells are not balanced which is causing the OVP alarm. you definately dont want to charge to anything below 100% as that is likely what has caused this issue to start with . The batteries require you to be charging them full every day to balance the cells , if you dont do that you get this result . Its hard to give advice at this point , i would personally connect to the battery BMS to monitor the cells at the top end and gradually push the voltage up to get the cells to balance (this takes time and you have to know what you are doing) , you most likely have cells in the 3,4V range while others are hitting 3,65v . This is not an easy problem to solve for the average person so i would recommend to take the battery back to supplier.

 

Your battery is not happy , the cells are not balanced which is causing the OVP alarm. you definately dont want to charge to anything below 100% as that is likely what has caused this issue to start with . The batteries require you to be charging them full every day to balance the cells , if you dont do that you get this result . Its hard to give advice at this point , i would personally connect to the battery BMS to monitor the cells at the top end and gradually push the voltage up to get the cells to balance (this takes time and you have to know what you are doing) , you most likely have cells in the 3,4V range while others are hitting 3,65v . This is not an easy problem to solve for the average person so i would recommend to take the battery back to supplier.

Is there any problem with starting the balancing at a much lower voltage. I have set my balancing on a DIY to start at 3.2V.

BMS is working great but I find that the SOC is always reported much higher than it should be based on the voltage per cell. 

It seems my DIY could outlive me. Nearly 4 cycles in 2 months as it does not get cycled a lot. Mostly LS. 

 

 

Is there any problem with starting the balancing at a much lower voltage. I have set my balancing on a DIY to start at 3.2V.

Yes , You do not want the balancer to start balancing in the flat part of the curve as that will actually unbalance your battery over time . Ideally you set your charge balance off so it does not balance while charging,and then set the balancing to start at 3,45V .  Even at 3,4v the curve is still pretty flat . I have found 3,45v(thanks to Andy from the Off-Grid garage) to be the perfect number to keep the pack super balanced . I have tested this with 2x 12v Revov 200Ah batteries ,initially they were very unbalanced when new but after gradually increasing the voltage up to 3,55V a cell with those settings changes it perfectly balanced them. 

 

Is there any problem with starting the balancing at a much lower voltage. I have set my balancing on a DIY to start at 3.2V.

That is the nominal voltage you start balancing at, maybe set it a bit higher closer to the drop-off voltage, it's senseless trying to balance lifepo4 at the flat part of the curve. See Andy at off-grid-garage, he has some interesting videos showing the optimal setup of JK Bmses

I have mine set to 3.4v to start balancing and max pack cell voltages to 4.5v and over voltage protections set to 3.60v and recovery at 3.56v this keeps my whole battery nicely balanced with lower than 0.05vDelta at working loads and less than 0.1v at top and bottom ends of cycles.
If it was up to me I would rip out all bmses from these factory batteries and replace them with JK BMSes 🥰

Edited September 30, 20232 yr by WannabeSolarSparky

What BMS does the battery have? Ideally you should connect to the battery and see what's going on at the cell level.

There are 2 levels of issues, a warning and a fault. Warnings are good cos the bms is telling the inverter there's an issue, so they are at least communicating. The bms is probably doing its job. A "fault" being issued is bad, a warning has been issued but the cell is still being charged.

FYI, even my pylontechs have ov warnings, it takes them a few charge/discharge cycles to settle down.

Discharge your battery down to 80% DoD(20% SOC), then disconnect it for 24hr, maybe the cells will equalize and then let it charge normally..See what it does. Repeat a few times...

Edited September 30, 20232 yr by FixAMess

 

Is there any problem with starting the balancing at a much lower voltage. I have set my balancing on a DIY to start at 3.2V.

BMS is working great but I find that the SOC is always reported much higher than it should be based on the voltage per cell. 

It seems my DIY could outlive me. Nearly 4 cycles in 2 months as it does not get cycled a lot. Mostly LS. 

 

Hi @Scorp007 are you using JK bms as i reconize the software page?

 

Hi @Scorp007 are you using JK bms as i reconize the software page?

Sorry my mistake as I had the intention to mention this is a JK BMS.

@WannabeSolarSparky @Nexuss @FixAMess Thanks for your valuable input. I normally only get the cells charged to about 3.4V. As can be seen on my picture the delta was only 4mV even if they were very fat from 100%. As charging/discharging is very shallow and less than 4 cycles in 2 months the delta of cells are always very close.

Because our supply is so stable with the longer power failure of 36 hrs which we had once in 33 yrs I don't really get a time to cycle the battery due to low power requirement. Currently cycle about 250Wh on some evenings during LS. I am just prepared if we have longer outings or if I have to heat water for heat pump from PV and/or battery power.

I did once discharge them down to about 10% and recharged and got the BMS to give a more accurate SOC but it was short lived before it started giving a higher reading. Now and again I get a 100% SOC even below 3.5V per cell. As it is not important as an indicator due to the way of cycling a live with it.

@FixAMess As it is a 20 cell BMS it is a mission to disconnect the BMS. In order to get it to switch on again means while disconnected one must connect a DC supply at least 5V higher than the battery before the BMS will operate from a 24V supply voltage as in my case. The cells are in a steel box and I have to work from the top about 500mm lower down and it feels like work. To get in the box I also need to disconnect and remove my inverter etc.

Sorry for hijacking the topic.

 

Thanks for your valuable input. I normally only get the cells charged to about 3.4V. As can be seen on my picture the delta was only 4mV even if they were very fat from 100%. As charging/discharging is very shallow and less than 4 cycles in 2 months the delta of cells are always very close.

You are most welcome   The delta will always be very small in the flat part of the curve even in a very unbalanced battery ... that is why you really need to get up into the steeper part of the curve to effectively balance the cells . I would recommend you charge with atleast 3,5V a cell so they get to balance above 3,45V. You will start to see the delta rise the higher you go. I aim to get them balanced at 3,55V to within 0.015V delta.

 

As it is a 20 cell BMS it is a mission to disconnect the BMS

I didn't mean disconnect the BMS, I meant disconnect from load/inverter to allow cells to equalize.

Edited September 30, 20232 yr by FixAMess

 

I didn't mean disconnect the BMS, I meant disconnect from load/inverter to allow cells to equalize.

You are confusing balancing of different batteries in a stack with the actual cells in a battery. Disconnecting a battery will never allow it to balance or  as you say 'equalize', only way to do that is to get your voltage per cell up to 3,5V plus. So you set the voltage on the inverter manually and watch the BMS via monitoring software .

I have been doing a lot of research on the Freedom Won batteries but especially the bms. Guys at FW is very transparent and helpful in every way to promote the quality and understanding of the pack. Guys like Barry Basson and Günter Boecker technical manager are always willing to disclose information to ensure best performance on their battery modules. I know @Steve87 has mention the Orion bms and this is some of the research that i have regarding the Orion bms totally in a class of its own. The complex algorithm to ensure balancing of the cells and i will share an extract from the documentation. Below extract of OrionBms workings.

"Balancing on the Orion BMS only occurs when the BMS is powered in CHARGE mode (powered by pin 3 on the Main I/O connector). When any one cell in the battery pack exceeds the Start Balancing voltage, the BMS will begin the balancing algorithm for all cells. The BMS will look for the lowest cell, then place a load on all cells which are more than the maximum difference in voltage above the lowest cell. For example, if a battery pack consists of 4 cells at 3.5, 3.51, 3.65 and 3.49 volts and the maximum difference in voltage is configured for 10mV (0.01 volts), the BMS would only apply a load to the cell which is 3.65v, to bring it down to within 10mV with the rest of the cells. This algorithm continues until all cells are balanced to within the pre-defined maximum difference in voltage and continues even after the BMS has switched off the charger. Once all cells are within this voltage, balancing will stop until power is removed and re-applied to pin 3 on the BMS (i.e. the next charge cycle).

The BMS has a safety feature to prevent over-discharging any cell during balancing in the event of a defective or dead cell. A minimum balancing voltage threshold allows the programmer to specify a voltage threshold at which the BMS is not allowed to remove energy from a cell. While the rest of the cells will continue to balance, the BMS will not place a load on any cell which is below this threshold, even if a cell below this threshold is needing to be balanced. The purpose of this feature is to protect the cells from over-discharge and to prevent a possible race condition where the BMS removes charge from alternating cells.

The start balancing voltage setting should typically be configured to a voltage that indicates a cell is within approximately 5-10% of the maximum state of charge. For iron phosphate this is typically about 3.5v and varies with other chemistries. The maximum delta voltage (difference in voltage from the highest to lowest cell) recommended is 10mV for most lithium ion chemistries such as iron phoshpate, but may be adjusted slightly lower for certain chemistries with a linear discharge curve (such as many manganese or polymer type cells.) A value too low will cause a race condition reducing or eliminating the effectiveness of the balancing algorithm and 10mV is recommended unless research has been done on a lower setting. When balancing a grossly out of balance pack, choosing a higher number such as 20mV may increase the speed of bulk balancing, but should then be reduced back to 10mV for finer balancing.

The minimum balancing voltage setting is simply to prevent cells from becoming over-discharged. This value can be set to a fairly low voltage, often a voltage corresponding to around 25% state of charge. For iron phosphate a voltage of 3.0 to 3.2v is appropriate. The minimum balancing voltage setting must be low enough to allow the BMS to effectively perform balancing and must be below the settling voltage.

While the BMS is balancing, the balancing will pause every so often to allow cell voltages to settle and to re-evaluate the balance of the cells in the pack. This is a normal part of the balancing algorithm and happens at set intervals. If the BMS unit itself is at an elevated temperature, the BMS will pause for a longer period of time to prevent overheating. To prevent a burn hazard, the BMS will not balance at all when the heatsink temperature is above 50C."

 

 

You are confusing balancing of different batteries in a stack with the actual cells in a battery. Disconnecting a battery will never allow it to balance or  as you say 'equalize', only way to do that is to get your voltage per cell up to 3,5V plus. So you set the voltage on the inverter manually and watch the BMS via monitoring software .

Sorry, yrs, you are correct. I was not thinking!

 

I have been doing a lot of research on the Freedom Won batteries but especially the bms. Guys at FW is very transparent and helpful in every way to promote the quality and understanding of the pack. Guys like Barry Basson and Günter Boecker technical manager are always willing to disclose information to ensure best performance on their battery modules. I know @Steve87 has mention the Orion bms and this is some of the research that i have regarding the Orion bms totally in a class of its own. The complex algorithm to ensure balancing of the cells and i will share an extract from the documentation. Below extract of OrionBms workings.

"Balancing on the Orion BMS only occurs when the BMS is powered in CHARGE mode (powered by pin 3 on the Main I/O connector). When any one cell in the battery pack exceeds the Start Balancing voltage, the BMS will begin the balancing algorithm for all cells. The BMS will look for the lowest cell, then place a load on all cells which are more than the maximum difference in voltage above the lowest cell. For example, if a battery pack consists of 4 cells at 3.5, 3.51, 3.65 and 3.49 volts and the maximum difference in voltage is configured for 10mV (0.01 volts), the BMS would only apply a load to the cell which is 3.65v, to bring it down to within 10mV with the rest of the cells. This algorithm continues until all cells are balanced to within the pre-defined maximum difference in voltage and continues even after the BMS has switched off the charger. Once all cells are within this voltage, balancing will stop until power is removed and re-applied to pin 3 on the BMS (i.e. the next charge cycle).

The BMS has a safety feature to prevent over-discharging any cell during balancing in the event of a defective or dead cell. A minimum balancing voltage threshold allows the programmer to specify a voltage threshold at which the BMS is not allowed to remove energy from a cell. While the rest of the cells will continue to balance, the BMS will not place a load on any cell which is below this threshold, even if a cell below this threshold is needing to be balanced. The purpose of this feature is to protect the cells from over-discharge and to prevent a possible race condition where the BMS removes charge from alternating cells.

The start balancing voltage setting should typically be configured to a voltage that indicates a cell is within approximately 5-10% of the maximum state of charge. For iron phosphate this is typically about 3.5v and varies with other chemistries. The maximum delta voltage (difference in voltage from the highest to lowest cell) recommended is 10mV for most lithium ion chemistries such as iron phoshpate, but may be adjusted slightly lower for certain chemistries with a linear discharge curve (such as many manganese or polymer type cells.) A value too low will cause a race condition reducing or eliminating the effectiveness of the balancing algorithm and 10mV is recommended unless research has been done on a lower setting. When balancing a grossly out of balance pack, choosing a higher number such as 20mV may increase the speed of bulk balancing, but should then be reduced back to 10mV for finer balancing.

The minimum balancing voltage setting is simply to prevent cells from becoming over-discharged. This value can be set to a fairly low voltage, often a voltage corresponding to around 25% state of charge. For iron phosphate a voltage of 3.0 to 3.2v is appropriate. The minimum balancing voltage setting must be low enough to allow the BMS to effectively perform balancing and must be below the settling voltage.

While the BMS is balancing, the balancing will pause every so often to allow cell voltages to settle and to re-evaluate the balance of the cells in the pack. This is a normal part of the balancing algorithm and happens at set intervals. If the BMS unit itself is at an elevated temperature, the BMS will pause for a longer period of time to prevent overheating. To prevent a burn hazard, the BMS will not balance at all when the heatsink temperature is above 50C."

 

Is this the BMS the eTower uses ? 

Andy just released a video about balancing which may be of interest as it explains/shows balancing in a nice visual which makes it easier to understand..

 

 

Your battery is not happy , the cells are not balanced which is causing the OVP alarm. you definately dont want to charge to anything below 100% as that is likely what has caused this issue to start with . The batteries require you to be charging them full every day to balance the cells , if you dont do that you get this result . Its hard to give advice at this point , i would personally connect to the battery BMS to monitor the cells at the top end and gradually push the voltage up to get the cells to balance (this takes time and you have to know what you are doing) , you most likely have cells in the 3,4V range while others are hitting 3,65v . This is not an easy problem to solve for the average person so i would recommend to take the battery back to supplier.

Thanks for the shared wisdom, I really appreciate it. I did check all 15 cells are 3.331V or 3.332V. They are balanced. I supposed the max values on the BMS are programmed incorrectly. I will leave the setup as it is for now. Thanks folks for all the help. I will monitor the voltage when the battery is close to 100% tomorrow morning.

 

Thanks for the shared wisdom, I really appreciate it. I did check all 15 cells are 3.331V or 3.332V. They are balanced.

As i explained to @Scorp007 unfortunately that does not mean they are balanced . If you look at the charge curve for LFP it will start to make more sense. The ONLY way to see how balanced a pack is to get up to the 3,5 v -3,6v range (the steep part of the curve). Edit* how did you check all 15 cells voltage ?

Edited October 1, 20232 yr by Nexuss

 

As i explained to @Scorp007 unfortunately that does not mean they are balanced .  Edit* how did you check all 15 cells voltage ?

The cells are shown in real time. Even the balancing current is shown on the left hand side. The Red is always the lowest cell and blue the highest. 

Only 8 cells. 

 

 

Edited October 1, 20232 yr by Scorp007

 

The cells are shown in real time. Even the balancing current is shown on the left hand side. The Red is always the lowest cell and blue the highest. 

Only 8 cells. 

Hi @Scorp007 That question was for @MightyDee hence the 15 cells .  I see that svolt battery has a screen , i assume thats how the cell voltages were obtained .