Guru
Joined: 13/10/2014
Location: AustraliaPosts: 2228
| Posted: 04:35am 02 Jan 2024 |
During the course of the morning, despite pouring rain, dark overcast sky, and only half of the solar panels in use, I was able to generate just under 1KW of solar.
That was enough to keep everything running on the inverter and hold the last 48v battery bank at the current level. However when we were briefly running at close to 3kW I got a disconnect / reconnect cycle from the Inverter, then a second cycle, so I switched to Mains priority.
The Auto Transfer switch is able to switch seamlessly between Mains AC and Inverter AC, for obvious reasons you would NOT want that cycle repeating for to long.
The DALY BMS with HW versions BMS-ST103-309E have Alarm data which it's accessed via the PC SW and also saved to disk in the History Data directory.
This is such a handy feature and it appears that only the CAN/Rs458 models have this capability. It showed:
Time: 2/01/2024 11:34
Err: ErrCellV_Low_LV2
Voltage: 52.6V
Current: -48.6A
Chg MOS: ON
DisChg MOS: OFF
Max CellV: 3.316 Cell 5
Min CellV 2.956 Cell 6
The Discharge MOSFET disconnected the DC supply to the Inverter, cloudy overcast and rainy day meant the Solar Charger could not keep the Inverter running (as it normally can) and this could have gone unnoticed until nightfall.
Now I was sure I had checked and double checked every terminal on the 16 Cells, so I set the Low V cutout in the BMS even lower, then switched the ATS back to Solar priority to investigate.
The Inverter took the now 2.5kW load without indication that anything had switched (seamless) and I got my favorite tool that won't accidentally short out a Cell terminal "My Finger" and felt the terminals and Link between cells 5 and 6, the Link was warm
. Some dumbarse had only finger tightened this one nut 
While on the subject of the DALY BMS - I have 3 of these and they all show random stupid values of charge and Discharge Current, but only when the Inverter is running, I'm now convinced that the Current Sensor in the BMS is not filtered correctly for HF/LF noise.
NO, changing the Fudge factor value in the DALY BMS for noise does not work - that is really only for noise around zero current.
This problem does effect the Battery Capacity calculations.
Fortunately the 400A JUNCTEK current shunt and battery capacity Meter is 100% noise immune and 100% accurate even down to a few mA, and it's always on so no need for an APP, although it also has Bluetooth and a phone APP if needed.
Below: The Inverter still running perfectly after it one an only hiccup a few months back. [Caused by and underrated Diode]
You can see the JUNCTEK LCD displays on each shelf, these display screens will be incorporated into a single panel between the top and middle shelf once the battery modifications are finished.
I have two 5 port USB hubs supporting 3 Active Balancers and 3 BMS units running back to the Main PC via a single powered extension 5m USB cable, a small Tablet can also use the single USB output locally. The wires showing next to the Active balancers, seen in the previous photos, are some RS252 to USB converters that I'm making up and are temporarily plugged into the UART sockets on the Active balancers.
This obviously allows one PC program to access any of the units on the fly.
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Edited 2024-01-02 14:41 by KeepIS