How can you getting Aux battery voltage (12v car battery voltage) from Nissan Leaf HV battery BMS CAN buss messages

[TrueSoln]

When have been looking at LeafSpy on BSM only mode,
its displaying the voltage of the Aux battery (12v car battery)
(Screen below show it as 11.82v )

Is that being decoded from a message sent out from Nissan Leaf Battery (BMS)?

Have look at message from HBAT in Dala git hub, and cant see it mentioned
https://github.com/dalathegreat/leaf_can_bus_messages

FYI: Leaf Spy is great tool for any one that is checking up on car battery states,
Very simple to make up a tool use for battery checking out of the car

 

[Dala]

On CAR-CAN (not EV-CAN), the 0x292 message has LeadAcidBatteryVoltage in byte3

 

[TrueSoln]

On CAR-CAN (not EV-CAN), the 0x292 message has LeadAcidBatteryVoltage in byte3

Must be version of it in EV-CAN else how leaf spy getting info
(Unless from the dongle)

I will try a few test with different car batteries and see if can spot a change with only a 12v voltage change

 

[Dala]

You can get it also by actively polling,

Name: Bat 12V Voltage (V)
Type: Integer
Description: The voltage of the 12 volt battery as read by the Leaf’s Vehicle Control Module ECU. The
Bat 12V Voltage is the fifth reply byte value times 0.08. In the example Bat 12V Voltage is 13.04V
Query: 0x797 03 22 11 03 00 00 00 00
Answer: 0x79A 04 62 11 03 A3 00 00 00
Formula: Bat 12V Voltage = ( data[4] * 0.08 )

 

[TrueSoln]

Query: 0x797 03 22 11 03 00 00 00 00
Answer: 0x79A 04 62 11 03 A3 00 00 00
Formula: Bat 12V Voltage = ( data[4] * 0.08 )

Is that not message for the VCM, or you think working requesting from LBC(BMS) also ?

 

[Dala]

It's from the VCM. Most likely Leafspy takes the voltage reading from the OBD2 hardware. No way to know, it is closed source

 

[TrueSoln]

@dala
Seems its not from the Canbus messages

When you connect a ELM327 module to ODB2 port you query voltage from the ELM327 protocols
ATZ - soft reset
ATI - gets the protocol info
ATRV - gets a voltage reading off the module

I'm playing with the ELM327 scanner tool now
Getting can message back from one of the can lines now
Not yet worked out how can use it to get data form the other two lines

Just the Car-CAN data back.
Want to see if can get the EV-CAN data back using these tools with out rewire of the plug