Energy Storage Box (ESB)

WARNING: This page is about a different car, the 2006 GMC Sierra, 2006 GMC Cab & Chassis Sierra, 2006 Chevrolet Silverado, and 2006 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The energy storage box (ESB) subsystem provides the capability to store electrical energy as chemical energy to provide the energy required by the Energy Management System. The ESB shall monitor the energy exchange along the 42-volt bus internal to the ESB and to provide status information to the hybrid control module (HCM). The 3 valve-regulated lead-acid batteries provide power for the 42-volt system. The "deep cycle" batteries employ Absorbent Glass Mat technology, specifically designed for hybrid vehicles, and are tailored to GM performance requirements. Lead-acid batteries are less costly to replace than nickel-metal hydride batteries or other battery technologies. They have a 50 to 55 amp hour Ahr. capacity and a projected 4-year life. The batteries are stored in a single energy storage module mounted under the rear seat. They power the electro-hydraulic power steering (EHPS) and the starter/generator. A conventional under-hood battery powers all the other electrical items, like the lighting, the driver information center (DIC) and the Infotainment system. The ESB physical content as follows:

3-Panasonic HV1255V valve regulated lead acid batteries, wired in series.
Energy storage control module (ESCM)
Service disconnect switch
2-120 V AC duplex outlet
Battery module vent tubing system
42-volt bus fuse
12-volt ventilation fan and outlet duct
Current sensor
42-volt harness and connector
12-volt connector and harness
120 V AC connector and harness

The ESB functional content as follows:

Store electrical energy into chemical energy
Receive 42-volt DC energy via the 42-volt bus for charging
Determine appropriate power mode
Monitor and calculates energy transfer and status
Monitor temperature of batteries
Monitor and control fan speed.
Monitor and control the battery cut-off (BCO) switch.
Provide an outlet interface to HVAC ventilation duct
Provide removal of battery gases
Provide a side impact 42-volt auto disconnect
Communicate faults/information via LAN messages

IMPORTANT: The Panasonic HV1255 VRLA batteries used in service will have approximately 80 percent state of charge (SOC) when shipped from the manufacture. BEFORE battery replacement, both the battery pack and faulty battery must be fully charged at the pack level (together) to ensure the vehicle battery pack will be equally balanced and charged. The new replacement battery will be charged to 100 percent SOC using the J 42634 Battery Module Charger before installation. See Special Tools . Refer to Battery Charging (Non-HP2) or Battery Charging (HP2) . The Service Charge Procedure MUST be performed at the pack level if:

The vehicle is not operated for a period of time.
The energy storage box (ESB) battery pack is less than 45 percent SOC.
One or more batteries are diagnosed for replacement.

Service Charge Procedure:

Install a scan tool.
Service Disconnect in the ON position.
Connect a MANUAL battery charger to the underhood battery positive remote jumper stud refer to and to engine ground. Turn on the battery charger and set to 40-amp setting.
Turn ON the ignition.
Select the SGCM Service Charge Procedure from Special Functions/SGCM Output Controls and select ON.
Turn OFF the ignition and disconnect the scan tool.

The starter/generator control module (SGCM) will continue the charging process and control the charging rate with the scan tool disconnected and the ignition off. The SGCM monitors the battery pack and will stop the Service Charge Procedure when 100 percent SOC is met. The battery charger will display a low current output when the process is complete and without battery damage. Base voltage for 100 percent SOC is +/-0.2 volts from 13 volts. The procedure is completed in 4-5 hours maximum.
The Panasonic batteries are designed to have a life span of approximately 62,000 amp hours.
If all 3 batteries are replaced, the total Ahrs. must be reset with a scan tool, through BECM Output Controls.
Individual Battery Charging: Replacement of one or more batteries require a unique charging procedure that must be followed for proper vehicle service. Refer to Battery Charging (Non-HP2) or Battery Charging (HP2) .