@Psy I've been monitoring my battery since day 1, I know I have one problem cell that does not get to full charge, I've informed the OEM, namely LBSA @Bain Viljoen. They answer was to bring the battery over and they will fix it. That is a big problem with the current state of affairs, load shedding twice a day, I cannot afford to be without a battery.  Here is a dashboard with the cell's voltage, one can clearly cell number 8 lags behind the rest. 

@Antonio de SaMy understanding is that it is also important to fully charge the batteries so as to ensure that the cells can be balanced by the BMS as the voltage differences in the middle of the SOC range are so small that they are almost impossible for the BMS to balance the cells. So if you only use your battery between 20 & 80% SOC for example, individual cells are more likely to get out of balance (depending on the BMS I would assume)

I think that the thing to remember is that not all battery BMS's are created equally.

The more expensive BMS's generally have better cell balancing and often use a shunt to determine the SOC rather than using individual cell voltages

8 minutes ago, Sc00bs said:

@Antonio de SaMy understanding is that it is also important to fully charge the batteries so as to ensure that the cells can be balanced by the BMS as the voltage differences in the middle of the SOC range are so small that they are almost impossible for the BMS to balance the cells. So if you only use your battery between 20 & 80% SOC for example, individual cells are more likely to get out of balance (depending on the BMS I would assume)

I think that the thing to remember is that not all battery BMS's are created equally.

The more expensive BMS's generally have better cell balancing and often use a shunt to determine the SOC rather than using individual cell voltages

and I would be willing to put money on it... This is exactly my issue.

Newer Narada batteries actually have a different BMS and I suspect that this may have been one of the reasons they updated it

Hi All

Just my 2cents so I have built a 15kwh bank its almost a year now. Build is 272amp cell with JBD bms with 10amp  active balancer. So what I have learned is that depending on ther charge/discharge rate your cell can get off balance but once fully charged the active balancer does its work.I charge between 80 to 90amps. 

5 hours ago, Antonio de Sa said:

@Psy Yes, the BMS takes care of that every time it reaches 100% soc.

FYI, the seplos has 3 parameters it uses to determine cell balancing/equalizing:

Equalization opening voltage: 3.5V

Equalization opening pressure difference: 0.05V

Equalization closing pressure difference: 0.03V

(they tend to use pressure and voltage interchangeably in the settings as well as other spelling errors)

So basically if any cell reaches 3.5V and there is a difference of 50mV between the highest and lowest cell then that cell will be balanced by releasing some of it's charge very slowly until the difference between the highest and lowest cell is down to 30mV, then balancing will stop altogether. It doesn't actually start balancing at 100% SOC, it's just that when the cell balancing conditions are met it is usually almost fully charged.

Duplicate post

Edited October 24, 20223 yr by jumper
Duplicate post

3 hours ago, Sc00bs said:

So if you only use your battery between 20 & 80% SOC for example, individual cells are more likely to get out of balance (depending on the BMS I would assume)

As far as the seplos in the shoto and quite a few other batteries is concerned, this is because the cell balancing only activates at 3.5V per cell so if you only charge to 80% the cells will never balance.

 

3 hours ago, Sc00bs said:

The more expensive BMS's generally have better cell balancing and often use a shunt to determine the SOC rather than using individual cell voltages

Seplos has passive, but slow balancing and a shunt to measure the current which seems to be quite accurate as far as I can see... at least as accurate as my axpert as the voltage readings are basically the same on both.

8 hours ago, jumper said:

As far as the seplos in the shoto and quite a few other batteries is concerned, this is because the cell balancing only activates at 3.5V per cell so if you only charge to 80% the cells will never balance.

 

Seplos has passive, but slow balancing and a shunt to measure the current which seems to be quite accurate as far as I can see... at least as accurate as my axpert as the voltage readings are basically the same on both.

Agree 100% that is exactly what I see in my battery.

To me, I considered the below well balanced.. Am I right or wrong?

This is controlled via voltage to the battery and then obviously the internal BMS from there. Unfortunately, I could not see this info when it was controlled via BMS directly

32 minutes ago, Jay-Dee said:

To me, I considered the below well balanced.. Am I right or wrong?

Looks great, just a bit strange that the "Min Cell Voltage" line doesn't actually show the lowest cell value.

1 minute ago, jumper said:

Looks great, just a bit strange that the "Min Cell Voltage" line doesn't actually show the lowest cell value.

I had not noticed that 🤣. I will let the developer know. He is great at fixing those sort of issues

1 minute ago, Jay-Dee said:

I had not noticed that 🤣. I will let the developer know. He is great at fixing those sort of issues

LOL at first glance I thought you had the most perfectly balanced battery in the world 🤣

Just make sure on those Naradas, they are 0.5C as far as I know so make sure to set a limit on discharge current.

11 minutes ago, Marcel said:

Just make sure on those Naradas, they are 0.5C as far as I know so make sure to set a limit on discharge current.

Nope, constant 1C on the 48NPC100 model... The smaller ones are less but this was one of the specific reasons I chose this battery initially.  Not that it is an issue any more as I cap it at 135A over the 2 batteries as more is not needed with a 5KW system 

On 2022/10/24 at 11:55 AM, Psy said:

This is why I am super sceptic about lithium's running without BMS, you can make it work but there is nothing protecting the batteries from deep-discharge.

I haven't read all the responses but nobody should ever run a Lithium battery pack without a BMS.  Deep discharge and overcharge can both cause a fire and would be trivial to have happen on a Lithium battery pack.

However what is being discussed here is not removing the BMS but removing communication between the inverter and the BMS.  At least that is how I'm reading it.  So the inverter is basically dumb and just constantly running at a given voltage.  Which is completely fine.

No BMS would be a BMS if it didn't have a mechanism to disconnect the battery to prevent the various safety scenarios.  In other words, the BMS doesn't even need the battery to be connected to anything to enter a fault protection mode.

Edited October 26, 20223 yr by Gnome

On 2022/10/21 at 9:30 PM, Jay-Dee said:

I am thinking it may be beneficial to let the inverter control the batteries via voltage instead for letting it communicate with the BMS but I was wondering what the negative effects would be (short or long term).

NOTE: My opinions and observations are 100% from a maverick DIY perspective. AND I AM NOT an electrical/electronics engineer AND strongly suggest you do not  try anything I do or suggest yourself unless you understand 100% what can go wrong AND HOW IT WILL AFFECT YOUR  battery and/or inverter warranty.

** Please also note that I generalise A LOT, especially between same battery chemistries (LiFePo4) All my info and observations DO NOT NORMALLY APPLY TO OTHER CHEMISTRIES and/or other Battery Brands!!!

I have 2 Narada 48NPFC100 batteries, pretty much the same as yours, I have also had similar issues and about a year ago I switched to NO INVERTER COMMS even after changing to the sunsynk inverter
In my opinion this is a far better way to run your batteries, but you need to make 100% sure ALL your Voltage settings are correct on the inverter AND BELOW the settings of the BMS and battery supplier suggested settings. This is especially important if your battery supplier does not allow you to set the BMS parameters to more sensible settings.

7 minutes ago, WannabeSolarSparky said:

NOTE: My opinions and observations are 100% from a maverick DIY perspective. AND I AM NOT an electrical/electronics engineer AND strongly suggest you do not  try anything I do or suggest yourself unless you understand 100% what can go wrong AND HOW IT WILL AFFECT YOUR  battery and/or inverter warranty.

** Please also note that I generalise A LOT, especially between same battery chemistries (LiFePo4) All my info and observations DO NOT NORMALLY APPLY TO OTHER CHEMISTRIES and/or other Battery Brands!!!

I have 2 Narada 48NPFC100 batteries, pretty much the same as yours, I have also had similar issues and about a year ago I switched to NO INVERTER COMMS even after changing to the sunsynk inverter
In my opinion this is a far better way to run your batteries, but you need to make 100% sure ALL your Voltage settings are correct on the inverter AND BELOW the settings of the BMS and battery supplier suggested settings. This is especially important if your battery supplier does not allow you to set the BMS parameters to more sensible settings.

I have been following your thread on the BMS replacement... I am presuming you did this as your BMS was wonky like mine has become.

I have been running this on voltage control with the Sunsynk... For the first 2 days, I ran it on AGM V and have now been running on AGM % for the last week and a bit. I am very comfortable with the voltage specs used as specified in the Narada spec sheet at 54.5v float and 54.0 charge... This seems to be working perfectly for me and I am getting perfect performance with dropping my batteries down to a daily 25% SOC based on the Sunsynks shunt measuring as this is keeping the voltage in the 48's and only dropping down under very large load at low SOC... At 25%, I am getting the expected 150Ah from my 2 batteries.

For me, this is where I am going to leave it, so long as I dont have any issues down the line. I am using ICM to monitor the cells and keep an eye out for any other issues but so far so good 

12 minutes ago, Jay-Dee said:

I have been following your thread on the BMS replacement... I am presuming you did this as your BMS was wonky like mine has become.

I have been running this on voltage control with the Sunsynk... For the first 2 days, I ran it on AGM V and have now been running on AGM % for the last week and a bit. I am very comfortable with the voltage specs used as specified in the Narada spec sheet at 54.5v float and 54.0 charge... This seems to be working perfectly for me and I am getting perfect performance with dropping my batteries down to a daily 25% SOC based on the Sunsynks shunt measuring as this is keeping the voltage in the 48's and only dropping down under very large load at low SOC... At 25%, I am getting the expected 150Ah from my 2 batteries.

For me, this is where I am going to leave it, so long as I dont have any issues down the line. I am using ICM to monitor the cells and keep an eye out for any other issues but so far so good

Yes with the older battery the BMS was a total bust/malfunctioning, it just was not doing what it's supposed to do I think it was from an old batch with the bad bms series.
The new battery works great for almost a year now and stays nicely balanced.
 

As for the JK BMS, I do not understand why the battery builders are not using the same SMART tech in their BMS's
I am so impressed with this JK BMS that I am considering voiding the warranty on the second good battery as well and putting in a JKBMS there too

I will NEVER buy a pre-built battery again unless/until they start using decent smart BMS's that I have full access to.

Last night was the 1st NORMAL cycle since replacing the faulty cell and running the JK BMS

Hi, I'm very new at this 🙂.  I have a 5kwh Sunsync inverter and a 10kwh Freedom Won Lite Home 10/8 Life PO4 lithium battery.  In terms of the voltage settings for the restart and switch off function on the inverter for the battery, what voltage should I set these on. On the battery spec it states "max/nom/min as 56v/42v/57v". Which voltage should I use for each setting plse, or does the battery's BMS automatically do this?

Also, on the equalization voltage, should those be at zero for a lithium battery and zero for days and hour settings? My installer tells me that this battery's BMS sorts this out and I don't need to worry,  please assist Thanks, Mark 

 

48 minutes ago, Markprop said:

My installer tells me that this battery's BMS sorts this out and I don't need to worry,  please assist Thanks, Mark 

Your installer is correct.

52 minutes ago, Markprop said:

Hi, I'm very new at this 🙂.  I have a 5kwh Sunsync inverter and a 10kwh Freedom Won Lite Home 10/8 Life PO4 lithium battery.  In terms of the voltage settings for the restart and switch off function on the inverter for the battery, what voltage should I set these on. On the battery spec it states "max/nom/min as 56v/42v/57v". Which voltage should I use for each setting plse, or does the battery's BMS automatically do this?

Also, on the equalization voltage, should those be at zero for a lithium battery and zero for days and hour settings? My installer tells me that this battery's BMS sorts this out and I don't need to worry,  please assist Thanks, Mark 

 

If your battery is communicating correctly with the inverter, then leave it as it is..

Our / my issue is that the BMS on my batteries is not working 100% and resulting in issues

Well, looks like I have the same issue after all with my Deye + Narada with the infamous Shinwa BMS : SOC reported by BMS doesn't make much sense. Battery reaches LV disconnect with a SOC of 60% and they are nowhere near full charge when reaching 100% SOC. Less than 50v @ 100% & they keep taking 40A for a while before reaching 51v. Like twice the amount of  time they need to go from 80% to 100% at constant 40A. SOC would probably be displayed as 150% to reach full charge if it was not stuck at 100% ...

Switching to voltage.

A shame after spending so much time to figure out proper com between Deye / Sunsynk & Narada 🙈

1 hour ago, zivva said:

Well, looks like I have the same issue after all with my Deye + Narada with the infamous Shinwa BMS : SOC reported by BMS doesn't make much sense. Battery reaches LV disconnect with a SOC of 60% and they are nowhere near full charge when reaching 100% SOC. Less than 50v @ 100% & they keep taking 40A for a while before reaching 51v. Like twice the amount of  time they need to go from 80% to 100% at constant 40A. SOC would probably be displayed as 150% to reach full charge if it was not stuck at 100% ...

Switching to voltage.

A shame after spending so much time to figure out proper com between Deye / Sunsynk & Narada 🙈

Have you tried voltage settings while at home to see how that would charge the battery? 

26 minutes ago, Scorp007 said:

Have you tried voltage settings while at home to see how that would charge the battery? 

It does charge until 51v ... Which is probably something like 150% SOC according to the BMS 🥳

Will check what BMS says about individual cell voltages using the BMS software ...

Here are the funny logs when charging with communication disabled.

100% SOC @ 50.860v with 30A all the way to still less than 51v and a SOC still displayed as 100% when getting 30A for 20 minutes ... 

 

Actually looks even worst : battery charged well above the 100% SOC, taking the 30A current all the way to 51.5v for like 30 minutes past the 100% mark. Was expecting that surplus not displayed to be stored somewhere but SOC decreases as soon as battery discharges.

Now trying to discharge down to 43.2v (Low Voltage Load Disconnect as per Narada specs ...) to see what SOC I get ...

 

Edit : 

Oops the 43.2v pretended limit for load disxonnect is way too low. SOC reaching 20% on the battery BMS but getting an UV alarm & battery stops discharging at 45v ... SOC calculation definitely wrong on that BMS

Edited January 8, 20233 yr by zivva