watonomous.github.io

[ Electrical Division : Battery Monitoring ]

Created by [ Rohan Kumar], last modified on Apr 29, 2020

[Overview ]

We have had to have the 12V auxiliary battery replaced in the bolty because it was drained after the rugged was left on overnight. To tackle this issue a discord bot has been created to notify the team if the battery is at critical levels (fluctuates 0.5V from the nominal voltage).

Background Research

We contacted a member of GM about the car's 12V battery and how the CAN signals were outputted, what to read, etc. The following is a brief overview of what was said, and the basics on the battery.

Unique CAN ID for the battery signal: 0x12A
The byte to read is the 3rd byte in the sequence of outputs (there should be 7 bytes total, therefore this byte is 3rd from the left)
Read only the 7 rightmost digits of the 3rd byte to get your value
The byte is not entirely accurate, to get a proper reading, divide the number by 10 and add an offset of +3

Implementation

Due to the nature of the problem and discords minimum requirement of python 3.5.3 for development we are running a docker container in which the bot is running on the Rugged. The bot is placed on the rugged for physical access to the CAN interface. The general idea is that the bot reads realtime battery data from the bus, computes a rolling average of the battery data from the last "X" seconds and compares it against the nominal voltage. The script only sends a message if the battery fluctuates more than 0.5V from its nominal voltage. The current code can be found here

TODO

Rolling average (partially complete)
Need to get nominal battery voltage reading, estimated around 12V?
Stream serial CAN data into the Docker Container look at: https://forums.docker.com/t/creating-and-sharing-virtualcan-network-interface-between-docker-containers/61596
Test the whole project
The channel id must be changed in Battery_Bot.py to the id of the channel that should be notified in the Wato server. In order to add the Battery Bot to the Wato server, the person adding the bot must have the "Manage Server" permission to do so. Follow all of the steps listed here to add the bot. The bot_token in Battery_Bot.py should also be replaced with the token found by going to the Bot page in the Developer Portal.

Useful Resources

Document generated by Confluence on Nov 28, 2021 22:40

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