Hi, i have 3 axpert max ii in parallel, currently only 2 are working. I have 6 100amp batteries ( china ), this morning i woke up and see that one inverter is on error 04, low battery voltage , but i have 30% of soc still.  I read somewhere to set 29 to 45.5v but it still showing error 04. 
 

also i notice that the first batterie is a little bit off with the others. I have them all connected to a busbar

Edited November 1, 20241 yr by Tsmithf

14 minutes ago, Tsmithf said:

I have 6 100amp batteries ( china ),

I assume that you mean you have 6 48 V nominal 100 Ah battery modules connected in parallel. By the looks, they are 15S LFP.

15 minutes ago, Tsmithf said:

also i notice that the first batterie is a little bit off with the others.

This could well be your problem. That first battery module seems to be getting most of the charge current, but it is therefore also doing most of the discharge work. So you effectively have about a 150 Ah battery, instead of a 600 Ah battery.

My guess is that your cables to the inverters are both at one end of the busbars. If you change them to connect to either end of the busbar, or preferably a little closer to the middle (say closest to modules 2 and 5, or between modules 1 and 2, and between modules 5 and 6), then the battery modules should share the load current and charge current more evenly. Since you have the three inverters, make sure that you have separate cables from each inverter to the bus bars. If you daisy chained the inverter wires, that may have contributed  to the  problem with the third inverter.

After this change, it will likely take weeks for the modules to balance reasonably well.

I note that once an 04 warning is triggered, it takes a battery voltage rise of 4.0 V before the warning goes away! This is so lead-acid.

Finally, your battery charge voltages (55.0 and 53.7 V) are appropriate for 16S LFP battery modules, but other aspects of your system  suggest that you have 15S LFP modules. Consider lowering these voltages  to 52.5 V and 51.8 V respectively. 

Thanks a lot for the advice on voltages. I changed the charge to 52.5 and float 51.8, also i have shutdown at 45.5, back to battery at 50 and back to grid at 48 is this correct?? Charging is at 60amps per inverter so 0.2C 
 

the inverters are connected to one side of the busbar an all the batteries follow.

So the best connection will be the 3 inverters in the middle and 3 batteries one side and 3 on the other side? 

the 3 inverters have their own 70mm2 cable to the busbar,with the same length and the batteries are connected with 25mm2 to the busbar also with the same lenght

also keep in mind this connection was made yesterday, cause you say that it eill take weeks before the modules to balance

 

thanks again

Edited November 1, 20241 yr by Tsmithf

On 2024/11/02 at 3:58 AM, Tsmithf said:

So the best connection will be the 3 inverters in the middle and 3 batteries one side and 3 on the other side?

It's tricky with so many inverters and so many battery modules.

It's best if you don't have the positive and negative of the inverters or battery modules "lined up" (same distance from the left edge of the bus bars). If you do, then the battery modules towards the edge do less of the work. If no one module is at the edge (maybe the positive connection is, but the negative connection is closer to the middle or even near the other end), then the current should share better.