diff --git a/dotfiles-old/bin/batterymonitor b/dotfiles-old/bin/batterymonitor
new file mode 100755
index 0000000..2949920
--- /dev/null
+++ b/dotfiles-old/bin/batterymonitor
@@ -0,0 +1,54 @@
+#!/bin/sh
+
+POLLING_FREQUENCY=1
+
+# ISO 8601
+alias date="date '+%Y-%m-%dT%T'"
+
+emit() {
+	printf "[%s] " "$(date)"
+	echo "$@"
+}
+get_current_level() {
+	# adapted from other script i wrote, also in the public domain
+	if [ "$(uname)" = "Linux" ]; then
+		# this is a dirty hack.
+		# acpi | awk '{print $4}' will print the battery percentage,
+		# and s/,$// strips the trailing comma.
+		# acpi -a will just print the power adapter status.
+		printf "%b" "$(acpi | awk '{print $4}' | sed 's/,$//') ($(acpi -a))"
+		return 0
+	elif [ "$(uname)" = "NetBSD" ]; then
+		printf "%b" "$(envstat -s acpibat0:charge \
+			| sed 1,2d \
+			| cut -d ':' -f 2 \
+			| awk '{print $1}' \
+			| cut -d '.' -f 1)"
+		return 0
+	else
+		printf "get_battery_status: unsupported OS" >>/dev/stderr
+		return 1
+	fi
+}
+
+! get_current_level >/dev/null \
+	&& printf "Unable to get battery status on this system.\n" >>/dev/stderr \
+	&& exit 1 \
+	|| true
+
+current_level=$(get_current_level)
+previous_level=$current_level
+
+emit "$(printf "Current level: %d%%" "$current_level")"
+
+while true; do
+	current_level=$(get_current_level)
+	if ! [ $current_level -eq $previous_level ]; then
+		[ $current_level -lt $previous_level ] \
+			&& emit "$(printf "Discharged: %d%% -> %d%%\n" $previous_level $current_level )" \
+			|| emit "$(printf "   Charged: %d%% -> %d%%\n" $previous_level $current_level )"
+		previous_level=$current_level
+	fi
+
+	sleep $POLLING_FREQUENCY
+done
diff --git a/dotfiles-old/manifest_file b/dotfiles-old/manifest_file
index a421643..ffd9b5e 100644
--- a/dotfiles-old/manifest_file
+++ b/dotfiles-old/manifest_file
@@ -16,6 +16,7 @@
 .config/displaym/i3wm/sxhkdrc
 .config/i3/config
 .config/i3status/config
+bin/batterymonitor
 bin/data
 bin/displaym
 bin/mnt