Index: dialin/hd/battery.py
===================================================================
diff -u
--- dialin/hd/battery.py	(revision 0)
+++ dialin/hd/battery.py	(revision 171d79a4dd35aa06f7216513c4d44f584561f76c)
@@ -0,0 +1,89 @@
+###########################################################################
+#
+# Copyright (c) 2020-2022 Diality Inc. - All Rights Reserved.
+#
+# THIS CODE MAY NOT BE COPIED OR REPRODUCED IN ANY FORM, IN PART OR IN
+# WHOLE, WITHOUT THE EXPLICIT PERMISSION OF THE COPYRIGHT OWNER.
+#
+# @file    battery.py
+#
+# @author  (last)      Michael Garthwaite
+# @date    (last)      3-28-2022
+# @author  (original)  Michael Garthwaite
+# @date    (original)  3-28-2022
+#
+############################################################################
+import struct
+from logging import Logger
+
+from .constants import RESET, NO_RESET
+from ..common.msg_defs import MsgIds, MsgFieldPositions
+from ..protocols.CAN import DenaliMessage, DenaliCanMessenger, DenaliChannels
+from ..utils.base import AbstractSubSystem, publish
+from ..utils.conversions import integer_to_bytearray
+
+
+class HDBattery(AbstractSubSystem):
+    """
+    Hemodialysis Device (HD) Dialin API sub-class for battery related commands.
+    """
+
+    def __init__(self, can_interface: DenaliCanMessenger, logger: Logger):
+        """
+        HDBattery constructor
+
+        @param can_interface: the Denali CAN interface object
+        """
+
+        super().__init__()
+        self.can_interface = can_interface
+        self.logger = logger
+        self.battery_percentage = 0
+
+    def get_battery_percentage_remaining(self):
+        """
+        Gets the battery percentage remaining
+
+        @return: int value of the back up battery.
+        """
+
+        return self.battery_percentage
+
+    def cmd_battery_percentage_remaining_override(self, percentage: int, reset: int = NO_RESET) -> int:
+        """
+        Constructs and sends the battery percentage remaining override.
+        Constraints:
+            Must be logged into HD.
+
+        @param percentage:  integer - Remaining percentage of the back up battery.
+        @param reset:  integer - 1 to reset a previous override, 0 to override
+        @return: 1 if successful, zero otherwise
+        """
+
+        rst = integer_to_bytearray(reset)
+        pct = integer_to_bytearray(percentage)
+        payload = rst + pct
+
+        message = DenaliMessage.build_message(channel_id=DenaliChannels.dialin_to_hd_ch_id,
+                                              message_id=MsgIds.MSG_ID_HD_BATTERY_REMAINING_PERCENT_OVERRIDE.value,
+                                              payload=payload)
+
+        self.logger.debug("override battery percentage remaining")
+
+        # Send message
+        received_message = self.can_interface.send(message)
+
+        # If there is content...
+        if received_message is not None:
+            if reset == RESET:
+                str_res = "reset back to normal"
+            else:
+                str_res = str(pct) + "% "
+
+            self.logger.debug("Battery percentage overridden to " + str_res + ":" +
+                              str(received_message['message'][DenaliMessage.PAYLOAD_START_INDEX]))
+            # response payload is OK or not OK
+            return received_message['message'][DenaliMessage.PAYLOAD_START_INDEX]
+        else:
+            self.logger.debug("Timeout!!!!")
+            return False