Log ZCell voltage, bus voltage and warning indicator status

zcell-warnings.sh

#!/bin/bash
#
# Polls the ZCell BMS REST API once per second and prints the
# voltage, bus voltage and warning indicator status if they've
# changed since the last poll.  Runs indefinitely.
# Requires `curl` and `jq`.
# 
# Note: this only looks at the first battery in the system
# (".list[0]" in the `jq` invocation).
#

if [ -z "$1" ]; then
	echo "Usage: $(basename $0) BMS_IP [POLL_INTERVAL]"
	exit 1
fi

STATUS_URL="http://${1}:3000/rest/1.0/status"
INTERVAL="${2:-1}"
LAST=""

echo "Polling ${STATUS_URL} at ${INTERVAL} second intervals"
echo "voltage bus_voltage warning_indicator over_current_warning over_voltage_warning battery_temperature_warning other_warning"
while true ; do
	WARNINGS="$(curl -s ${STATUS_URL} | jq -r '[
		.list[0].voltage,
		.list[0].bus_voltage,
		(if .list[0].warning_indicator then "W" else "_" end),
		(if .list[0].over_current_warning then "C" else "_" end),
		(if .list[0].over_voltage_warning then "V" else "_" end),
		(if .list[0].battery_temperature_warning then "T" else "_" end),
		(if .list[0].other_warning then "O" else "_" end)
		] | join (" ")')"
	if [ "$WARNINGS" != "$LAST" ] ; then
		echo -e "$(date --iso-8601=seconds)\t${WARNINGS}"
		LAST="${WARNINGS}"
	fi
	sleep $INTERVAL
done