YamBMS_behavior.md

YamBMS behavior

Shunt and BMS combination

The various counters above allow you to see what state your system is in.

Shunt/BMS combine status

• Combine Availability : This status indicates whether the BMS or Shunt meets the conditions to be combined.
• Can be combined : This status indicates whether the BMS or Shunt is currently combined.

Shunt

Combine condition :

1. the Combine switch is enabled
2. Shunt Online Status is ON (the shunt Voltage is > 0)

If one of these two conditions is not respected, the shunt is automatically uncombined.

Important

In RS485 modbus multi-node, if a server does not respond (cable or hardware failure) the Online Status of the shunt will be set to OFF and it will be uncombined.

As soon as you import a Shunt and it can be combined (see condition) the values ​​Voltage, Current, Power and SoC of the shunt(s) will take precedence over the BMS values.

Note

If all BMS are uncombined the shunt data will no longer be published.

BMS

Combine condition :

1. BMS Online Status is ON / Connected (to detect a loss of connection with the BMS e.g. cable, BMS OFF or dead)
2. The BMS Battery Capacity is > 0 (to ensure that the data received is correct)

If one of these two conditions is not met, the BMS is automatically uncombined.

Important

In RS485 modbus multi-node, if a server does not respond (cable or hardware failure) the Online Status of the BMS will be set to OFF and it will be uncombined.

From YamBMS 1.5.1 :

The binary_sensor does not only represent the state of the charge/discharge switches but simply whether the charge/discharge is allowed. The value of binary_sensor is related to the status of the switches/alarms.

The errors_bitmask should not be a condition to combine a BMS anymore, let the BMS decide if the charge/discharge is allowed (its alarm system takes care of that).

The errors_bitmask continues to be analyzed to send warnings/alarms on the CAN bus.

The behavior of the Charging Instruction and Discharging Instruction sensors responsible for the instructions sent to the inverter will also be adapted. Alarm analysis will no longer be checked. If at least one BMS allows charging, charging can continue, if at least one BMS allows discharging, discharging can continue. This will also be based on the binary_sensor related to the state of switchs/alarms of the BMS.

If a BMS blocks charging or discharging, the permitted current is automatically reduced.

State of Charge

The SoC is slightly manipulated before reaching 0% or 100%. SoC 100% will be sent to your inverter only when the battery is fully charged (useful for some inverters stopping charging when the SoC reaches 100%).

SoC behavior:

1. If SOC < 99% real SoC is sent
2. Else if the battery is fully charged real SoC is sent
3. Else SoC 98% is sent

RGB LED status

This only applies to boards with an RGB LED.

Color	Status
$${\color{red}Red}$$	HA or MQTT KO + CANBUS KO
$${\color{green}Green}$$	HA or MQTT OK + CANBUS KO
$${\color{blue}Flashing-Blue}$$	HA or MQTT KO + CANBUS OK
$${\color{cyan}Flashing-Cyan}$$	HA or MQTT OK + CANBUS OK

CAN bus link

For the CAN bus link to be established with your inverter, the two conditions below must be met:

1. At least one BMS is in service (the number of combined BMS must be > 0)
2. Your inverter sends an ACK 0x305 every 1s (the link will be faulty if no ACK is received for 5s)

If these conditions are not met, the application waits 60s before trying to connect again.

Extra infos

Sending CAN frames continues without an inverter connected is problematic and will lead to ESP32 crash.

During boot the CAN bus links are activated directly if at least one BMS is combined and the inverter responds to the sending of CAN frames within a 5s delay. This 5s delay represents the time during which the link is valid, this timer is reset each time an ACK 0x305 is received from the inverter. This 5s delay can be modified in the configuration when importing the canbus package.

  canbus1: !include
    file: packages/yambms/yambms_canbus.yaml
    vars:
      canbus_id: 'canbus1'
      canbus_name: 'CANBUS 1'
      canbus_node_id: 'canbus_node1'
      canbus_light_id: 'esp_light'
      # The CANBUS link will be considered down if no response from the inverter (ID 0x305) for 5s
      canbus_link_timer: '5s'

If the inverter does not respond with an ACK 0x305 within this 5s delay the sending of CAN frames is paused for 60s this delay cannot be modified when importing the canbus package but you can modify it in the code if you need to.

BMS alarms

If all BMS have alarms, the alarms are sent to the CAN bus as Protection Alarms.

If at least one BMS has no alarms, the alarms are sent to the CAN bus as Warning.

Both text_sensor Alarm and Warning show the alarms/warnings currently transmitted to the inverter.