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I agree, with two inveters you double your chances of something actually failing.

What was the eventual outcome here?

In Cape Town the municipal by laws require a COC irrespective of whether you have a grid connection or not. I would think that your insurance company would also require a COC, otherwise how would they now the internal wiring was up to standard. Pretty sure the same would apply in the rest of SA, would need a COC, just not the part of the COC dealing with grid connection.

My geyser is installed outside the house on the garage roof so it is exposed to the cool night air in Cape Town. It used to be inside the roof, but could not fit the 200L through the trap door when we changed form a 150L to 200L about two years ago. Also actually prefer the outside install since it is now right next to the HP and a lot easier to replace once the inevitable happens and it starts leaking. I have not yet insulated it, I do heat to 60°C, I have noticed that changing this to 55°C has a disproportionate impact on the running time.

Is also have a heatpump (5.4kw ITS), also on a 200L geyser (installed outside the house on the flat garage roof) I left the heatpump on when we were away from home in December, so basically no one used any of the hot water. It ran for 55 minutes each morning to heat the water up to 60°C again. It did not turn on again until the next morning. When we are home and use the hot water it takes about 90 minutes to get the water up to 60°C in the morning and then it will turn on again round about 3PM and run for about 25 minutes. Don't know the C to which the water inside the geyser is cooled to when used. We are 4 people. Heatpump is set not to run between 5PM and 7AM.

On my batteries with a PACE BMS the SOH is calculated only when you do a deep discharge and hit UVP on any cell. By example, let's say it is a 100AH original capacity, and you hit UVP on a cell when the battery SOC is 5%, then the SOH will be set at 95% (being the 100% original capacity less then 95% you used until UVP). Just note that this is firmware based, and since PACE supplies hardware to a number of different battery manufacturers with different firmware needs the logic might well be different on different batteries. I had a few videos of this since I tested it a while back with a battery that had a bad cell to show the manufacturer what was happening for the warranty claim. I completely ignore SOC on my batteries (with the exception of cell balancing) and use voltage alone without BMS communication. I use SA to taper down charge current as voltage increases to ensure sufficient absorption time. Have set the PACE BMS to trigger 100% SOC when pack voltage hits 55.2v AND the charge current drops below 0.5 Amp in order to make sure cell balancing is triggered (once charge current stops cell balancing only continues if the 100% SOC was triggered). I try and do a deep discharge (sub 2% SOC) at least once every quarter to check battery health.

It is my understanding that the never Pace BMS boards do not come with the RS232 port. Unfortunately I cannot help more than this. Perhaps ask Esener. You can connect to the BMS using the RS485 port using a different version of PBMS tools. The one limitation here, at least with the older BMSes, is that you cannot change BMS settings (which can be done using the RS232 port), apart from this the sofrware displays the same information.

Perhaps temporary shading from, by example a chimney. Is the drop in current at exactly the same of is it slowly moving later/earlier? I won't be the mppt dialing anything back since it produces more current and power later in the day.

Tend to agree with your logic. Are you able to write to the BMS (change the settings) using PBMS tools. Not all versions of the software can write to the BMS, also think the PC to BMS connections needs to be to the RS232 serial port (as opposed to the RS485 mod port) Edit 1: a reset won't change the parameters, you need the correct version able to write to the BMS as described above Edit 2: also interesting to see that the Full Capacity is reducing every time there is a protection event (put differently, the SOH is reducing each time an OCP event is triggered). You can reset the SOH back to 100% using the correct version of PBMS tools, it might void your warrenty if you still have one. Perhaps contact the supplier for a firmware update. It can be loaded using the same version of PBMS tools that can write to the BMS. I have this version which I can share with you if you are interested but as said it might void your warrenty.

I thought that might be the case, but saw the column header was A, which is why i then checked my logs (which does show A, but with the decimal on the correct spot)

A BMS protection event won't necessarily trigger a fault. Looking at the pictures you have posted, the BMS goes into protection mode due to overcurrent events (OCP). Based on the BMS settings the charge and discharge overcurrent protection is triggeredat 110A and then looking at the event log it seems like the load exceeded the 110A at the point the protection was triggered. The BMS will release the protection based on the OCP delay time setting. You mentioned in your post that the battery shuts down irrespective of the load, the log seems to tell a different story (although I am not 100% on how to read the log, assume by example the 13570 current in the second line is 135A, not to sure if you can confirm). I checked one of my logs (also PACE) and the log shows the current with the decimal indicator at the correct place which seems to be different to your picture)

Do you have these pictures at the time that the batteries report 0% SOC? I am assuming that the BMS of each battery stays powered on, but the discharge mosfets are closed due to some protection being triggered. Can you overlay the SOC graphs with the graphs showing the load placed on the batteries. Are the SA readings taking directly from the master battery RS232 or RS485 ports ? If they are, you can use the SA cable to read the data directly into PBMS tools or PBmodbus tools depending on which port you are using. Based on your earlier posts the size of the SOC drops seems to be getting larger (10%, 20% and then 40%) which to me indicates cell imbalances that are progressively getting worse. I am not sure if the BMS will turn off the entire bank if one battery reaches and UVP state.

If the problem is getting worse then I would think it points to cell imbalances or faults as opposed to a potential BMS issue. In all the troubleshooting that your installer did, was the cell voltages inspected to determine if there are potentially weak cells. Poor fuse connections on the battery lines can sometimes cause low DC bus voltage failures, especially if each battery is individually fused through a common bus bar (if daisy chained normally not an issue). Do you have access to monitor the individual cell voltages to see what the delta is at high SOC levels (above 3.5v per cell) and at the lower SOC levels (below 3.1v per cell). If you don't have access to cell voltage data, you can also try to charge the batteries to 100% SOC, turn off the PV (switch off the breakers, under very low load) and then apply a large load to see if the batteries can carry this as a high SOC, if they can it is almost certain that the low voltage dc bus errors are caused by weak cells. Another factor to consider is how often is the bank charged to 100% SOC in order for the cells to properly balance and to rest the BMS SOC counter. This needs to be done as frequently as possible, if not daily. If the are cells imbalanced you can also try and charge up the bank at low C rates (0.2) for an extended period of time (4 weeks plus), charging at 3.5v per cell (56v for a 16 cell battery) and keep the float setting at 56v as well which should force the BMS to balance the cells at that level. Also just make sure that the 56v is within the battery specs per the supplier. If there are weak cells, then nothing can really be done, apart from insiting on a warrenty replacement). Switching to AGM mode will only mask the issue, it wont solve it

The AM2s are NMC vs the LBSA LFPs, they cannot be used together.

LiBMS screen showing 100A discharge limit. Something likely wrong with the inter battery communication, or dips switches set incorrectly or something not correct with the battery inverter communication.

Where is the battery temperature measurement taken from (average of the cells, FETs, other). If not cell tempreture, it would be interesting to see that metric as well if possible since it should be a fair margin higher compared to ambient. I have about a 11°C increase between cell tempreture and "inside the battery enclosure" temperature during extended periods of cold temperatures as long as I cycle the cells.

Anyone opted out of the new terms that is still on the Beta program and receiving the updates?

Anyone else noticing that SA is now charging for the software updates?

56v is not high for a 16cell LFP battery, it is actually still very much in the safe zone. I would even say that 55.5v is on the "very low" side since charging at this voltage you will never get into the "knee" of the LFP charging curve which in turn means you won't give your cells appropriate opportunity to balance. The reason why you lost so much on the SOH side is because one or more of the cell was likely triggering an OVP alarm which will cause the BMS to set the new "full capacity" equal to the "remaining capacity" at the time the cell triggered the OVP alarm. By example if the SOC is 80% at the time the OVP alarm is triggered the SOH becomes 80%, really stupid feature of some BMSes. The firmware update that was done hopefully removed this. The revov cells are 2nd life, so they do require some extra care ito frequent balancing and perhaps lower charge rates (charging at lower Amps), but I see no issue with the 56V. More than likely the tech set the charge volts to 55.5v because of a cell hitting OVP and not because this is what the manual says.

Cell voltages look fine, but the voltages in the picture is still at the flat part of the voltage curve and probably meaningless to look at. What does look odd here is the low charge rate of battery 2, at that SOC it should be charging at a rate closer to the other 3. Is it expected for the cycle count to be so vastly different between the 4 batteries? I would remove battery 2 from the bank to see if this had any impact on the remaining 3 when they are used without no 2. I assume you are using open loop, ie no comms between inverter and batteries?

The PACE BMS has 3 trigger points that reset SOC to 100%. The first is if any cell reaches OVP (normally 3.65v) The second is if the battery reaches the battery OVP (normally 58.4v for 16 cell battery) The last is based on a combination of battery voltage and charge current (usually set at when the charge current is below 2A and the voltage is above 57.6v). All of the above can easily be changed with PBMS tools. All of those standard setting are to high. Have left setting 1 and 2 unchanged on my batteries but have changed no 3 to 56v and 0.5A). The ideal position to be in is the 3rd trigger above as this avoids any over voltage alarms. When the BMS triggers 100% SOC it closes the charge MOSFET and it will continue to balance the cells even though charging has stopped. Conversely, if the 100% SOC is not triggered the BMS will only balance the cells if a charge current is supplied. There is another factor that might influence those erratic SOC values. What is the state of health of each of your batteries? If one is say at a SOH of 80% if means that the SOC is calculated based of 80AH capacity as opposed to 100AH which can also result in the not so uniform SOC readings. I know on the SA pictures they are reported as 100%, has this been verified by actual BMS readings? I also see that the battery capacities are different (on the SA pictures), this will also contribute to the SOC differences, albeit not by much.

Provide this picture at 56.4v please

Shoto uses a PACE bms if I recall correctly? Have you checked if the batteries starts discharging at the same time, in other words, after fully charging them to 100% SOC and then using the batteries to supply the load, does each battery start discharging at the same time? The PACE BMS will close the discharge MOSFETS when a cell triggers the Overvoltage Protect alarm during charging, normally set at 3.65v. The BMS will keep the discharge MOSFETS closed as it is trying to balance the cells even though the inverter might be pulling load from the other batteries. So you might have a situation where 1 or 2 of the batteries only start supplying load when the others are already down to 90% SOC (by example). The bigger the battery bank the more pronounced this effect can be, since the BMS will only open the MOSFETS when the load warrants it (is big enough), and since you have 4 batteries in the bank this will need to be a substantial load. This effect is also more pronounced in winter since the batteries have less time to balance the cells. I had the same issue, eventually solved it by adjusting settings to avoid hitting OVP. The local importer could not solve this, eventually the Chinese manufacturer pointed us to PACE who supplied me with a sollution.

A 40mV difference in the flat part of the curve is rather substantial. The graph is not clear enough to see what happens in the "knee" of the charge curve (above 3.45v). If it was me I would have it looked at. To what voltage do you charge to? Does each cell reach at least 3.5v ever so often during charging?

I don't think PACE makes a BMS with active balancing in the 100A verianty. I am open to being corrected though, or perhaps this battery has an bolt on active balancer. A passive balancer won't be able to bring that cell back in line.