Guru
Joined: 13/10/2014
Location: AustraliaPosts: 2232
| Posted: 05:48am 04 Feb 2024 |
Thoughts on the larger DALY-BMS LCD Touch screen display:
The LCD is shown sitting above four JUNCTEK battery monitor screens in the last picture posted. The screen comes in two flavors of COM port, UART or RS485. Not all DALY BMS will have a CAN/RS485 port, I have the UART unit as one of my four BMS does not have RS485. The Screen comes with a short cable with a 6 pin plug on each end. The BMS UART port and LCD screen port use the same 6 pin connectors.
I purchased eight 6-pin plug and socket sets, these come with fly-leads attached and they 100% match the DALY UART ports, found some on line for low cost. So glad I also got the sockets.
The LCD monitor itself only needs 4 connections to work, +12v, RX data, TX data and Ground.
You could use an external +12v supply, but 12v would need to be interrupted as you switch between each BMS, the DC supply interruption is needed to force a re-read of data from the BMS and to start coms with each selected BMS.
There is a pin on the BMS UART port that supplies +12v, there is an optional 5th wire if you wanted to utilize the BMS Activate / Deactivate function using a momentary push button switch, IMHO you really want this.
The 6th wire in the UART socket is +3.3v and not needed for the LCD screen.
I have four BMS units that I wanted to monitor these without using a phone, Bluetooth or PC.
I initially thought this LCD was a bit of a gimmick device, but I really like the unit now. It does most of functions of the PC software, but does not handle the active balancer settings, and you cannot set the cell high or sum high voltages, you still need the PC SW to do that.
I used a separate 12v plug pack to power the LCD, this is powered by a UPS which also powers the Network routers, VIOP, StarLink and the main Solar logging micro controller and main PC.
My solution worked out really well as it allows just one UART connection to have access to any BMS device and its active balancer or display them on the DALY LCD.
Note: The LCD will also display the cell voltages read by the Active balancer, but it cannot change the current or voltage trip values in the balancer.
I happen to have a 5 pole 8 position switch, hard to get these days, but there are small IC to do this now.
The 5 poles are for 1: RX-D, 2: TX-D, 3: Activate button, 4: Ground and 5: 12V from the plug pack. The +12v is interrupted as the switch rotates, the switch wafers are break before make, this causes the LCD to request a data update from the selected BMS.
The 8 positions allows me to select any BMS or Active balancer to display on the DALY LCD monitor, or switch to the PC software via the USB connection.
The COMS switch is a 3 pole 2 position switch (Jaycar) it changes the selected COMS RX-D, TX-D and GND lines between the UART PC cable and the DALY LCD screen.
A DALY PC to USB adapter that comes with the each BMS, plugs into the switch via one of the socket sets I purchased, the LCD display and the COMS to each BMS and Active Balancer also use these plug sets.
The BMS UART output is TTL (3.3v) level, so switching between each BMS does not affect the PC serial connection or Software when it's running, switching back and forth between the LCD screen and PC connection / software is also seamless. It means I can start the PC Software and leave it running on a small tablet or laptop, then switch between any BMS without the need to touch the Laptop / tablet or LCD to show the results.
To overcome any ground issues, it's important to switch the ground connections with multiple BMS, that's why one bank of the switch is for ground switching between devices.
The charge and discharge FETS in the negative battery connection conduct through the FET body diodes in the OFF state. Joining thin ground wires together could cause problems if that bypasses the body diodes of a BMS that has a disable MOS switch.
The DALY LCD is easy to read, allows quite a few settings to be simply changed and has 3 screens of data, including the typical page of individual voltage for - in my case - 16 LFP cells. Touch response is good.
The only negative is that it needs to be angled correctly to get good contrast, I was able to do this easily, in use this has not been a problem at all.
Since acquiring an accurate DVM, I have found the DALY BMS voltages to be very accurate and within a few mv of the displayed voltage, the current display is also accurate, except for it's poor immunity to Inverter noise, but the JUNCTEK battery bank monitors handle that perfectly.
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