12V Auxiliary Battery

This procedure covers the removal and replacement of the 12V auxiliary battery in a 2023 Chevrolet Bolt EUV, which requires partial high-voltage battery access and component removal.

Warnings

Tools required

Parts

• 12V AGM auxiliary battery × 1 — GM 84652528 or equivalent Group 47 AGM
• Battery hold-down bracket hardware × 1 — Use OEM specification
• Coolant line O-rings × 2 — Use OEM specification

Fluids

• ACDelco DEX-COOL (Orange) — 1.5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure vehicle has been off for minimum 30 minutes to allow high-voltage system to enter safe state
3. Open hood and locate 12V battery in engine compartment (driver side)
4. Document or photograph all electrical connections and routing before disassembly
5. Ensure replacement battery is same specification (AGM, Group 47, minimum 520 CCA)
6. Have tech2win or equivalent scan tool available for post-replacement module wake-up if needed

Procedure

1. 1

   Disconnect 12V auxiliary battery
   Disconnect the negative terminal first using a 10mm socket, then disconnect the positive terminal. Secure cables away from terminals. Remove the protective cover from the battery compartment if equipped.
2. 2

   Raise and support vehicle
   Lift the front of the vehicle using a floor jack at the designated lift points. Support vehicle securely on jack stands rated for at least 4,000 lbs. Remove the front driver-side wheel to access underbody components.
3. 3

   Remove underbody splash shield
   Remove the plastic underbody splash shield fasteners using appropriate trim tools or 10mm socket. Lower the shield to expose the battery cooling system and high-voltage battery area. Note the location of all fasteners for reinstallation.
   ℹ️Some fasteners may be single-use push-pin type. Inspect and replace if damaged during removal.
   Torque spec

   Cover Screws11 Nm (8 lb-ft)
4. 4

   Drain battery coolant circuit
   Locate the coolant drain point on the battery thermal management system near the 12V battery area. Place drain pan beneath the drain point. Carefully open the drain valve or remove the coolant line fitting using a 13mm wrench. Collect all coolant for proper disposal. Expect approximately 1-1.5 quarts to drain.
   ⚠Coolant may still be warm. Allow adequate cooling time if vehicle was recently operated.
   Torque spec

   Coolant Line Fittings15 Nm (11 lb-ft)
5. 5

   De-energize high-voltage system
   Locate the high-voltage disconnect service plug under the rear seat (center position). Remove rear seat cushion by releasing clips. Remove the service plug cover and extract the high-voltage service disconnect by pulling straight up. Store the service plug in a secure location away from the vehicle. Wait a minimum of 5 minutes for high-voltage capacitor discharge.
   ⚠️Verify high-voltage disconnection with multimeter before proceeding. Orange cables must show 0V DC between any two conductors.
6. 6

   Verify high-voltage de-energization
   Using a digital multimeter rated for minimum 600V DC, verify zero voltage across accessible high-voltage terminals. Check between positive and negative terminals at the service disconnect location. All readings must show 0V DC. Do not proceed if any voltage is detected.
7. 7

   Disconnect battery coolant lines
   Wearing high-voltage insulated gloves, locate the coolant lines connected to the 12V battery thermal jacket. Using a 13mm wrench, carefully disconnect both inlet and outlet coolant line fittings from the battery. Cap or plug the lines to prevent contamination. Inspect O-rings and replace if damaged.
   Torque spec

   Coolant Line Fittings15 Nm (11 lb-ft)
8. 8

   Remove battery sensor connections
   Disconnect the battery current sensor connector from the negative battery cable. Press the locking tab and pull straight out. Disconnect the battery temperature sensor connector if equipped. Note routing for reinstallation.
9. 9

   Remove battery hold-down assembly
   Using a 13mm socket, remove the battery hold-down bracket bolts. There are typically two bolts securing the top hold-down bracket. Lift the bracket away and store hardware for reinstallation. Inspect bracket for damage or corrosion.
   Torque spec

   Bracket Bolts20 Nm (15 lb-ft)
10. 10

    Remove auxiliary battery
    Carefully lift the 12V auxiliary battery straight up and out of the battery tray. The battery weighs approximately 40-45 lbs. Inspect the battery tray for corrosion, debris, or coolant leaks. Clean tray thoroughly with baking soda solution if corrosion is present, then rinse and dry completely.
11. 11

    Install new auxiliary battery
    Place the new 12V AGM battery into the battery tray, ensuring it is properly seated and oriented with positive terminal in correct position (towards front of vehicle). Verify battery type matches OEM specification (Group 47 AGM).
    ⚠Ensure battery is AGM type only. Standard flooded batteries are not compatible with this vehicle's charging system.
12. 12

    Install hold-down bracket
    Position the battery hold-down bracket over the battery. Install and torque the bracket bolts to specification in a cross-pattern to ensure even clamping force. Verify battery is secure and cannot move in any direction.
    Torque spec

    Bracket Bolts20 Nm (15 lb-ft)
13. 13

    Reconnect coolant lines and sensors
    Install new O-rings on coolant line fittings if old ones show any wear. Reconnect both coolant lines to the battery thermal jacket, torquing fittings to specification. Reconnect the battery current sensor and temperature sensor connectors. Verify all connections are fully seated.
    Torque spec

    Coolant Line Fittings15 Nm (11 lb-ft)
14. 14

    Refill battery cooling system
    Using ACDelco DEX-COOL orange coolant, refill the battery cooling circuit through the fill point until coolant reaches proper level. Burp the system by gently squeezing coolant lines to remove air pockets. Add additional coolant as needed to reach proper level mark.
15. 15

    Reconnect 12V battery terminals
    Connect the positive terminal first, ensuring clean metal-to-metal contact. Torque terminal bolt to proper specification using connector bolt torque value. Connect negative terminal second and torque to same specification. Apply anti-corrosion spray to terminals if desired.
    Torque spec

    Connector Bolts7 Nm (5 lb-ft)

Reassembly

1. Reinstall underbody splash shield and secure all fasteners to specified torque
2. Reinstall driver-side front wheel and torque lug nuts to manufacturer specification (140 Nm/103 lb-ft)
3. Lower vehicle from jack stands
4. Reinstall high-voltage service disconnect plug under rear seat, ensuring it clicks fully into place
5. Reinstall rear seat cushion
6. Start vehicle and verify all warning lights extinguish normally
7. Check battery cooling system for leaks around all fittings

Verification

• Verify 12V battery voltage reads between 12.6-12.8V with vehicle off using multimeter
• Start vehicle and verify charging voltage reads between 13.8-14.4V
• Check for diagnostic trouble codes using scan tool and clear any battery-related codes if present
• Verify battery cooling system has no leaks at coolant line connections
• Confirm all electrical systems function normally (windows, climate control, infotainment)
• Test drive vehicle and verify all safety systems operate correctly (ABS, stability control, power steering)
• Verify battery current sensor is reporting properly through scan tool live data
• Check coolant level after initial drive cycle and top off if necessary

Related trouble codes on this vehicle

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