Honda Odyssey Service Manual: Battery Management System Description

When the battery sensor detects the battery voltage decreasing, that information is sent to the gauge control module via the UART line. The gauge control module then operates a beeper, and displays the message Switch Off All Lights and Electrical Devices on the multi-information display (MID) or information display to inform the customer that electrical devices should be turned off. If electrical devices are not turned off and the battery voltage decreases more, the gauge control module sends an interior lights off signal to the MICU and the rear MICU via the B-CAN line. Based on that signal, the units cut off the ground circuits of the interior lights and turns them off.

NOTE: The message on the multi-information display (MID) is not applied to '12-13 models.

   While the engine is idling, the battery sensor measures the battery current, voltage, and temperature values, and sends this data to the gauge control module via the UART line. The gauge control module sends the idle speed control signal and alternator control signal to the PCM via the F-CAN line. Then, based on those signals, the PCM determines the idle speed that is appropriate for the current state of charge of the battery, and also controls the alternator output. These functions help maintain the battery condition and improve the fuel economy.
If the battery sensor detects any problems, a warning message appears on the multi-information display (MID) or information display to inform the customer that the system needs attention.

NOTE:

• Even though the engine is not idling, the warning messages will be shown as long as the ignition switch is ON (II).

• If there are any problems with the charging system or the battery, the charging system indicator comes on at the same time.

• ''REPLACE BATTERY'' and ''BATTERY CHARGE LOW'' messages on the multi-information display (MID) are not applied to '12-13 models.

• The most common causes for "Battery Charge Low" messages are:

  1: Short-trip driving.

  2: Using the vehicles electrical devices, like the audio system, or aftermarket electrical devices for long periods of time with the engine off and the ignition switch in ON (ll).

• If the "Battery Charge Low" warning appears after fully charging the battery, disconnect the gray 2-pin connector next to the Battery Sensor for 10 seconds, then reconnect the connector; and the warning is removed from the display.

• If you need to replace the battery, replace it with a new battery of the same group size.