Add charge time formatting for times greater than 1 hour

main.go

@@ -428,5 +428,5 @@ func formatDuration(d time.Duration) string {
 	h := d / time.Hour
 	d -= h * time.Hour
 	m := d / time.Minute
-	return fmt.Sprintf("%02d:%02d", h, m)
+	return fmt.Sprintf("%02dh%02dm", h, m)
 }