TheOracle

Good point. For example, the buck transistor (at least one of them) could have shorted. I was thinking that it shot up to 57 V too quickly for that, though. But maybe there was such a short, bringing the voltage up to say 54.5 V, and the BMS decided it had enough of that and disconnected, and that sent the inverter's "battery" voltage to 57 V.
I was also thinking that the battery voltage was jumping around a little too much. Maybe one of the SCC transistors was shorting intermittently, just for seconds at a time, and only when the SoC reaches about 89% does this cause the battery voltage to trigger the BMS to disconnect.
Yes. Overshooting the target voltage that suddenly and that far is not typical Axpert solar charger behaviour.

Is that coming from the inverter (via monitoring software) or from the battery's BMS (via monitoring software or something that talks directly to the BMS)?
If it's coming from the inverter, it is fairly meaningless.
That's really weird. You are only charging from solar, and the solar goes away... and the battery voltage goes high! It looks to me that the battery is disconnecting for some unknown reason. The inverter isn't designed for this (some later models are), so the "battery" voltage (voltage at the battery terminals of the inverter) goes wild.
Then the battery decides to connect again, but now its voltage is quite low (perhaps 49.5 V, or about 3.33 V per cell, which is the resting voltage of LFP cells when not charging or discharging for some time). After a minute or two, the solar charger starts charging again.
Is it possible that when the inverter thinks that the battery volage is bouncing around near 51.5 V that it's actually much higher? Yet the voltage is so flat, it's like the LFP cells are nowhere near fully charged. They might indeed be at 89% SoC.
Perhaps there is a cell that is much fuller than the others, and its voltage rockets to about 3.6 V at this overall SoC. That could cause the battery to disconnect. But I'd expect the battery to give some sort of warning, or you should at last be able to find something in logs. Sorry, I know nothing about Pylontech batteries, other than the 48 V models are 15S LFP.
Especially considering the recent battery firmware update, I'd concentrate on the battery side for now.

@Coulomb  there might also be the possibility that the SCC voltage regulation is not functioning as it should be . I would like to suggest that @TheOracle performs the same charging cycle but with the PV input disconnected and the grid charger enabled .  I infer from the solarassistant graphs that the BMS went into protection mode and as a result the SCC charge voltage went up to 57V for about 7 minutes before the machine was restarted. That's not what I am used to in terms of the Axpert battery voltage regulation. I have in many occasions booted the Axpert with a 52V  bench supply with a blocking diode , and I still get stable regulation from the grid charger. I expect the SCC charger to match this stability.

You can get a zip file with versions for the old (2.8) and new (2.1) chip here -> Lithium storage unit Pylontech US2000C/3000C | Effekta | EFFEKTA Regeltechnik GmbH. I have seen V2.2 for the new chip US3000C Pylontech's but haven't been able to source it.

I believe the power saving mode is disabled when you have paralled inverters.

Dear @Sonoff Africa, Welcome. I think we should put together a box of Sonoff goodies to be put into the lucky draw system to celebrate your forum section! 😆
Let me know your thoughts.
Sincerely
Jason

Do not look for the cheapest one. Talk to the seller and expose your problem. Perhaps he would agree to a trial.

Well, there are generators and generators. With one that is fairly stable it should work. Important is to limit the charging current (11) on inverter settings according to the power capacity of the generator. Divide its rated power by 50V to get its 48V battery charging current capability.  Apply 10 to 20% safety margin.
12V 100Ah is peanuts in comparison with the 3kWh you have. Improve your system with additional battery of the same type and more PV panels. In the long run it's the better investment.
 
 

It's slightly low, he had it at 52.5 which is the "forum gold standard", as a suggestion to avoid some possible overshooting. But it would not cause the battery to stop charging at 50% SOC, I would not think.
Ah. Then your firmware is 73.00e, not 73.00 as you said. That threw me off. Sorry, I find it hard to keep track of all the people I talk to on these forums.
So what voltage does the battery get to when it finishes charging? According to the inverter (front panel or monitoring software) and multimeter at the battery preferably.
Perhaps you have voltage drops on your cables. Putting setting 26 back to 52.5 V may help slightly with this. Are your battery cables at least 35 mm²? Though with a maximum charge current of just 20 A, I would not expect this to be a problem, unless they're really thin (like 4 mm² or something).

Note that this is for the US3000C pylontech
Pin 6 = CAN-GND    = Green        =GND
Pin 7=  485A            =Br/Wh         =A+
pin 8=  485B            =Br                =B-
Have a look see in the manual PG 8.
So this works for me ,,USE AT YOUR OWN RISK.


us3000c-manual-eng-inutec.pdf

Congratulations.
Technically, the firmware is the LFP flavour of patched firmware version 73.00e; the "1" comes from the "U1" settings label for main firmware versions, when they are non-patched. Other firmware versions have labels U2 through U4; only U2 on your model (and only when there is PV power available to power the Solar Charge Controller).

Are you running the 52.5 V bulk/absorb setting (setting 26)? If so, as an experiment, knock it down a notch to 52.4 V and see if that helps. Otherwise, change it to 52.5 V, as 53.2 V is way too high. My guess is that the battery is disconnecting due to excessive battery voltage. It will disconnect at 54.0 V, and Axperts have a propensity to overshoot the set voltage.

No. For your model (same as my two), you need the LFP flavour of patched firmware version 73.00e . It's not mandatory to update the firmware, but it will make life easier.
.No, because you don't have an RS-485 port or the removable display processor to talk to the BMS.

I take it that the US3000C runs the same as the US3000B.
In that case, the generally recommended values (here in the forum) are Bulk 52.5V and Float 51.8V.
You can find the detailed explanations for those values somewhere here in the forum.
I have been running with these values for 2 years without problems.

I am running those settings as well and they are perfectly suited for US2000;US2000B;US2000Plus;US2000C;US3000A;US3000B;US3000C;UP5000

Hi guys,
@Jaco de Jongh is right: Pylontech US3000 should be charged to 52.5 at least.
 
Details:
Why 52.5V? Because the internal balancers kick-in at 3.480V per cell which translates to 52.2V. The 0.3V difference is the space that allows balancers to operate safely.
If you charge to 52V only (3.466V per cell) then the balancers won't start and the pack will become ubalanced over a long period of time.
If you will charge to 53.5V, then the balancers will have to burn much more energy and the temperature of the pack will rise. But still okay.
If you will charge to 53.6V, then the internal overvoltage protection will throw an error and the battery will disconnect itself.
Beware,  that even if you set your charger to 53.5V, there still will be a short spikes of power that will push the voltage over, based on the changing light conditions. Therefore, using the upper voltage limit is not a good idea. By the way, these spikes of power are the reason why in the past you've experienced 100% SOC even when charging to 52V only. Looks like the light conditions has changed since, and now there's not enough power spikes to push the voltage over and start the balancers.
 
@Ironman if you want to know more about Pylontechs, just check my LAB, the link is in my signature.

Why not? Whether you have one string or 6 strings, I would put a fuse on them all. With DC breakers you have some sort of technology that can fail. Buzz bars arching and getting stuck, springs can break, etc. Very limited technology in a fuse. Not a lot that can go wrong with them. They reach the set amperage, they blow. It is like pulling the trigger on a revolver (the fuse). If there is a bullet in the chamber and the hammer comes down on it, the shot will go off. On a pistol (DC breaker) it depends if loaded the bullets correctly in the magazine, inserted the magazine correctly, you cocked it correctly, excess dirt, etc. Many things that can cause it to jam and not to fire. 
I would put the fuse close to the panels and the DC breaker close to the inverter. If anything goes wrong with the panels, hopefully the fuse would blow. If anything goes wrong with the cables coming all the way down, through the roof and eventually to the inverter, then the DC breaker would hopefully take care of it. It would also act as a backup, should the fuse not blow for some reason. 
 

Thanks Jako, the battery voltage was just over 12,6V but I'm still returning that one. 

Verry good price 
Max charging amps for a single string 30A. Max charging for 5kva 60A solar + 60A utility.
Just limit the max charging amps in your settings.
But my experience you can leave it on 60A due to the agm battery drawing less & less amps the higher the soc. So at 50% DOD the batteries does not pull anything close to 30A. You cannot push amps into a battery. It draws what is required. But you can limit the initial current draw.
Yes they will work for you.

Thanks to Chris and Chris, I received the balancer this afternoon.
Already installed, hopefully it will help.