🔧 Fusion - 12V Battery Replacement

This procedure covers replacing the 12-volt auxiliary battery in your Fusion Energi. The 12V battery powers the computers, locks, lights, and startup systems, even though your Fusion also has a high-voltage hybrid battery.

Difficulty Level: Beginner | Estimated Time: 30-60 minutes

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⚠️ Safety & Precautions

• ⚠️ Your Fusion Energi has a high-voltage hybrid system. Do not touch orange cables, high-voltage connectors, or hybrid battery components.
• ⚠️ This job is only for the 12V battery, not the high-voltage traction battery.
• ⚠️ Always remove the negative battery cable first and install it last to reduce the chance of a short circuit.
• ⚠️ Wear safety glasses and gloves. Batteries can leak acid and release flammable gas.
• ⚠️ Keep metal tools away from both battery terminals at the same time.
• ⚠️ Battery disconnect is required for this repair.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 13mm socket
• 3/8-inch ratchet
• 3/8-inch extension 6-inch
• Battery terminal puller (specialty)
• Battery terminal cleaning brush
• Digital multimeter
• Memory saver 12V OBD-II type (specialty)
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 12V auxiliary battery AGM type - Qty: 1
• Battery terminal anti-corrosion protectant - Qty: 1
• Battery terminal felt washers - Qty: 2

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📋 Before You Begin

• Park your Fusion on level ground, shift to Park, and set the parking brake.
• Turn the vehicle fully off and remove the key/fob from the cabin area.
• Open the trunk and make sure you have good lighting.
• If using a memory saver, plug it into the OBD-II port before disconnecting the battery. A memory saver is a small backup power supply that helps keep radio presets and computer memory alive.
• Wait at least 5 minutes after shutting the vehicle off before disconnecting the 12V battery so control modules can go to sleep.
• Assumption: This is for the trunk-mounted 12V auxiliary battery used on the Fusion Energi.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Access the 12V Battery

• Open the trunk and lift the trunk floor panel by hand.
• Use your hands to remove or fold back the trunk trim panel covering the battery area.
• The 12V battery is located in the trunk area, not under the hood.
• Take a photo before removing cables.

Step 2: Check the New Battery Matches

• Use your eyes to compare the old and new batteries before disconnecting anything.
• Make sure the positive and negative posts are in the same positions.
• Make sure the battery is an AGM type. AGM means Absorbent Glass Mat, a sealed battery design used in many hybrid and stop-start vehicles.

Step 3: Disconnect the Negative Cable First

• Use a 10mm socket and 3/8-inch ratchet to loosen the negative cable clamp nut.
• The negative terminal is marked with a minus sign - and usually has a black cable.
• Twist the clamp gently by hand and lift it off the battery post.
• If the clamp is stuck, use a battery terminal puller (specialty). A terminal puller safely lifts a tight cable clamp without prying against the battery case.
• Move the negative cable aside so it cannot spring back and touch the battery post.

Step 4: Disconnect the Positive Cable

• Use a 10mm socket and 3/8-inch ratchet to loosen the positive cable clamp nut.
• The positive terminal is marked with a plus sign + and usually has a red cover or red cable.
• Lift the positive cable off the battery post by hand.
• Do not let the positive cable touch bare metal.

Step 5: Remove the Battery Hold-Down

• Use a 13mm socket, 3/8-inch extension 6-inch, and 3/8-inch ratchet to remove the battery hold-down fastener.
• The hold-down is the bracket that keeps the battery from moving while driving.
• Set the bracket and fastener aside in a safe spot.

Step 6: Remove the Old Battery

• Put on nitrile gloves and safety glasses.
• Lift the battery straight up and out using both hands.
• Batteries are heavy, so keep your back straight and lift with your legs.
• Place the old battery upright on the ground.

Step 7: Clean the Cable Terminals

• Use a battery terminal cleaning brush to clean the inside of both cable clamps.
• Clean until the metal looks bright, not dull or chalky.
• If there is white or blue-green corrosion, avoid touching it with bare hands.

Step 8: Install the New Battery

• Lower the new 12V auxiliary battery AGM type into the tray by hand.
• Make sure the positive and negative posts face the same direction as the old battery.
• Use the 13mm socket, 3/8-inch extension 6-inch, and 3/8-inch ratchet to reinstall the battery hold-down.
• Tighten the hold-down securely. Do not crush the battery case.
• Torque to 9 Nm (80 in-lbs) if using a torque wrench.

Step 9: Connect the Positive Cable First

• Install one battery terminal felt washer on the positive post.
• Place the positive cable clamp onto the positive battery post by hand.
• Use a 10mm socket and 3/8-inch ratchet to tighten the clamp nut.
• Torque to 5 Nm (44 in-lbs) if using a torque wrench.
• Make sure the clamp does not twist by hand after tightening.

Step 10: Connect the Negative Cable Last

• Install one battery terminal felt washer on the negative post.
• Place the negative cable clamp onto the negative battery post by hand.
• Use a 10mm socket and 3/8-inch ratchet to tighten the clamp nut.
• Torque to 5 Nm (44 in-lbs) if using a torque wrench.
• A small spark can happen when reconnecting. That is usually normal.

Step 11: Protect the Terminals

• Spray or apply battery terminal anti-corrosion protectant to both terminals.
• Use only a light coating.
• Reinstall any red positive terminal cover by hand.

Step 12: Reinstall Trunk Trim

• Reposition the trunk trim panel by hand.
• Lower the trunk floor panel back into place by hand.
• Make sure no tools are left near the battery.

Step 13: Verify Battery Voltage

• Use a digital multimeter set to DC volts.
• Touch the red meter lead to the positive terminal and the black meter lead to the negative terminal.
• A healthy new 12V battery should usually read about 12.4-12.8 volts with the vehicle off.

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✅ After Repair

• Start your Fusion and confirm the dash powers up normally.
• Check that the trunk lights, power locks, windows, infotainment screen, and exterior lights work.
• If the one-touch window feature does not work, fully lower the window, then fully raise it and hold the switch up for 2 seconds.
• If warning lights appear, drive normally for a short trip. Some modules may relearn after battery power is restored.
• Recycle the old battery at an auto parts store or battery recycler. Do not throw it in household trash.

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💰 DIY vs Shop Cost

Shop Cost: $280-$450 (parts + labor)

DIY Cost: $180-$280 (parts only)

You Save: $100-$170 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.5-1.0 hours.

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🎯 Ready to get started?

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