I have 2x SPF5000ES inverters with 2x 5.1 LBSA LifePo4 batteries with Solar Assistant managing my inverters as well as batteries via RS232/485 cable and has been working great. After a recent outage where the batteries were completely drained a few times due to cable faults directly after loadshedding, the batteries will refuse to charge to 100% SOC. It reaches the absorption voltage at 56V and goes back to 54V which would indicate that the battery is full but it will not go to 100% SOC. It seems to get to 80% and sometimes to 86% or 89% was the highest SOC reading. I checked the batteries and there are no errors and even Solar Assistant shows battery state of health as 100%.

I contacted LBSA a while back and they told me per mail and via telephone call that I need to set both the bulk and float to 56v which I have done but now I am not sure what to do?

both batteries are on around 500 - 600 cycles so I am far away from the guaranteed 7000 cycles that LBSA stand by.

Has anyone had this before? Could it be that the batteries are trying to self balance or equalize and that is why it is not charging to 100%?

Any assistance will by appreciated.

Edited December 19, 20222 yr by uncappedshady

@uncappedshady, Is there a way that you can read the individual cell voltages, I basically have a similar system, 2 x Growatt inverters, only difference is I only have one LBSA battery.

From day one, one of my battery cell voltages is lagging behind the other 15 however, maybe in your case you could have more than one problem cells.

By charging to 56 V and float at 54 V I can still get my battery to 100% SOC.  

I can see from my monitoring system that once any cell gets to 3.5 V it starts to equalize.

Take the battery to LBSA and let them test it, after all they offer 10 years guaranty. I know with load shedding one needs the batteries as a backup, you have two of them so take one at the time.

By the way how old are your batteries? 

See dashboard of my battery individual cell voltages.

 

So funny enough as I posted this the batteries SOC went up to 90% as it constantly charges then stops again the charges again and stops etc. 
 

What I can post now is my Solar Assistant high, avg and low values on cells as I am not home at the moment. 
 See below current readings of pack1 and pack2.

PS the batteries was installed in March 2022 so very new still.

 

 

Edited December 19, 20222 yr by uncappedshady

5 minutes ago, uncappedshady said:

So funny enough as I posted this the batteries SOC went up to 90% as it constantly charges then stops again the charges again and stops etc.

This is standard behavior with the Seplos BMS it will be balancing and it can sometimes take a while which is why LBSA suggested changing the float to 56V because at 54V is too low to get cells above 3.5V, so the lower ones can't catch up. It probably just needs more time, the BMS will prevent any overcharging as it will disconnect the charging circuit as soon as it reaches 100%SOC.

Your battery cells voltage looks pretty well balanced. Maybe you should follow LBSA advice and float it at 56 V for a while and see the results.

Edited December 19, 20222 yr by Antonio de Sa

Thanks all for the replies, I will give it some more time to see if it gets to 100% SOC. Unfortunately I have a 4 hour lodahedding slot coming up from 12:00 - 16:00 and here where I live each time after a 4 hour lodshedding slot the substations trip and we could be off for days after so I am holding thumbs that we just have the 4 hours down. 
 

for interrest, here are my settings:

PS: it is on user2 mode as the batteries could not be connected to my SPF’s directly. Solar assistant is the middleman where it reads the inverter values and the battery independently and never had an issue with it before now. 

 

Edited December 19, 20222 yr by uncappedshady

I would recommend set shutdown voltage to 48 V, also if you are not connecting the inverter coms to the battery, set battery type parameter 5 on the Growatt to USE. if you change that you will have to set parameters 19, 20 and 21 again.

What is your setting on parameter 1 ?

I see you have your setting on SNU, in that case when there is no PV you will be charging the battery with grid power. 

 

 

Thanks for the reply. I have my home assistant connected to solar assistant via MQTT and my home assistant determines the mode that my inverters need to be in based on LUX sensors I have as well as time to loadshedding so that gets controlled automatically. I have set the battery cutoff to 48V as per your recommendation though. Thanks for that. 
 

based on the USR2 setting I have read the below and LBSA also informed me to use USR2 based on the battery type I have. Please see below excerpt from diysolar forum.

Edited December 19, 20222 yr by uncappedshady

UPDATE: I am glad to report that my batteries are again 100% SOC.

Thank you to all for the assistance. I finally think I understand how the batteries internal BMS work now in order to balance the individual cells. 
 

 

9 minutes ago, uncappedshady said:

Thanks for the reply. I have my home assistant connected to solar assistant via MQTT and my home assistant determines the mode that my inverters need to be in based on LUX sensors I have as well as time to loadshedding so that gets controlled automatically. I have set the battery cutoff to 48V as per your recommendation though. Thanks for that. 
 

based on the USR2 setting I have read the below and LBSA also informed me to use USR2 based on the battery type I have. Please see below excerpt from diysolar forum.

Sorry to disagree with this statement, but maybe they are right, they are the experts. However, believe me the battery BMS will never allow the battery to be overcharged. As I told I have a homemade battery monitoring system and I can clearly see the battery BMS doing what it supposed to do. once the individual cell voltage gets to 3,5 V stops charging those cells and it goes in to equaling mode, if the voltages go to 3,6 V it stops charging all together. I can show you on the attached dashboard.

See the last 7 days of my system bellow.

 

7 minutes ago, Antonio de Sa said:

Sorry to disagree with this statement,

That statement is misleading and I also disagree. The USE mode will only apply too high a charge voltage if the user sets a too high voltage. USE mode and US2 modes are identical in all respects when no comms cable is present. US2 exists to fill the gap between a Li Protocol and USE mode, i.e. no protocol for LI exists in the Inverter but the comms are possible.
 

Edited December 19, 20222 yr by zsde

So if I set it to USR what else do I need to change?

1 minute ago, uncappedshady said:

So if I set it to USR what else do I need to change?

You will have to set again parameters 12, 19, 20, and 21. If your inverters are running in parallel you only have to change it in one of your inverters, also you will have to change the charging currents in parameters 2 and 11, these settings you have to change in both inverters.

 

Another thing that I would recommend is that don't keep the floating voltage at 56 V, once you reach 100% SOC set it to 54 V. or even lower 53,5 V 

That is what I see are the ideal voltages in my LBSA battery.

Perfect thanks.

My cells don’t go above 3.0 volts and im on less than 300 cycles