🔧 Focus - Battery Replacement

You’ll remove the old 12V battery from the engine bay and install a new one with the correct orientation and tight connections. After replacement, your Focus may need a quick Battery Monitoring System (BMS) reset so charging works correctly.

Difficulty Level: Beginner | Estimated Time: 0.5-1.0 hours

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⚠️ Safety & Precautions

• ⚠️ Turn the car fully OFF and keep the key away from the car while working.
• ⚠️ Wear gloves and safety glasses; batteries can leak acid and make flammable gas.
• ⚠️ Always disconnect the negative (-) cable first and reconnect it last.
• ⚠️ Do not let a tool touch both battery terminals at once.
• ⚠️ Battery disconnect is required for this job.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 13mm socket
• 1/4" ratchet
• 3/8" ratchet
• 6" socket extension
• Torque wrench (in-lb and ft-lb)
• Battery terminal puller (specialty)
• Battery post/terminal cleaning brush
• Trim clip tool
• Work light
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 12V battery (correct fitment for your Focus) - Qty: 1
• Battery terminal anti-corrosion felt kit - Qty: 1
• Battery terminal protectant spray - Qty: 1

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📋 Before You Begin

• Park on level ground, shift to neutral, set the parking brake, and open the hood.
• Make sure all lights/accessories are OFF and the key is away from the car.
• If you want to keep radio presets, use a memory saver (optional). Not required, just convenient.
• Plan to do the BMS reset after install (steps included below).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Access the battery

• Open the hood and locate the battery in the engine bay.
• If there’s a battery cover or intake snorkel blocking access, remove it using a trim clip tool and/or 10mm socket.

Step 2: Disconnect the negative (-) cable

• Use a 10mm socket to loosen the negative (-) terminal clamp nut.
• Lift the negative cable off the battery post and move it aside so it can’t spring back.
• If it’s stuck, use a battery terminal puller (specialty). (This tool gently lifts the clamp off without prying.)

Step 3: Disconnect the positive (+) cable

• Flip open the red terminal cover (if equipped).
• Use a 10mm socket to loosen the positive (+) terminal clamp nut.
• Lift the positive cable off the battery post and move it aside.

Step 4: Remove the battery hold-down

• At the battery base, remove the hold-down bolt using a 13mm socket, 3/8" ratchet, and 6" socket extension.
• Lift out the hold-down bracket and set it aside.

Step 5: Remove the old battery

• Lift the battery straight up and out. Use gloves and lift with your legs; it’s heavy.
• Set the battery on the ground (upright).

Step 6: Clean the terminals and prep the new battery

• Use a battery post/terminal cleaning brush to clean corrosion from the cable clamps.
• Install the battery terminal anti-corrosion felt kit (one on each post) if you’re using it.

Step 7: Install the new battery

• Place the new battery into the tray in the same orientation as the old one.
• Reinstall the hold-down bracket and bolt using a 13mm socket.
• Tighten with a torque wrench: Torque to 25 Nm (18 ft-lbs).

Step 8: Reconnect the positive (+) cable first

• Install the positive (+) clamp onto the battery post.
• Tighten with a 10mm socket, then final-tighten with a torque wrench: Torque to 6 Nm (53 in-lbs).
• Close the red terminal cover (if equipped).

Step 9: Reconnect the negative (-) cable last

• Install the negative (-) clamp onto the battery post.
• Tighten with a 10mm socket, then final-tighten with a torque wrench: Torque to 6 Nm (53 in-lbs).
• Spray both terminals lightly with battery terminal protectant spray.

Step 10: Reset the Battery Monitoring System (BMS)

• Turn ignition ON (engine OFF).
• Within 10 seconds: flash the high beams 5 times (use the headlight stalk), then press and release the brake pedal 3 times.
• Watch for the battery light to flash (confirmation).
• If it doesn’t confirm, repeat once, a bit faster.

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✅ After Repair

• Start the engine and confirm normal cranking and stable idle.
• Check that headlights, radio, and power windows work normally.
• Verify the battery is secure (no movement) and terminal clamps don’t rotate by hand.
• If you see a charging/battery warning light after driving, redo the BMS reset.

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💰 DIY vs Shop Cost

Shop Cost: $200-$450 (parts + labor)

DIY Cost: $120-$280 (parts only)

You Save: $80-$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?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.