🔧 Sonata - 12-Volt Battery Replacement

Replacing the battery involves removing the cables and hold-down bracket, lifting out the old battery, and installing a correctly sized replacement. Your Sonata does not require battery registration or coding after replacement.

Difficulty Level: Beginner | Estimated Time: 30-45 minutes

Assumption: These instructions apply to the original U.S.-market battery mounting and cables.

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⚠️ Safety & Precautions

• Turn the ignition and all electrical accessories completely off before touching the battery.
• Wear safety glasses and chemical-resistant gloves. A battery contains corrosive acid and can release flammable gas.
• Never place a metal tool across the battery terminals.
• Disconnect the negative terminal first and reconnect it last. This reduces the risk of an electrical short.
• Keep the smart key at least 6 feet away so the vehicle cannot be switched on accidentally.
• Do not pull, twist, or pry against the battery sensor attached to the negative cable.
• The battery is heavy. Lift it vertically with both hands or use a battery lifting strap.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 12mm socket
• 3/8-inch-drive ratchet
• 3/8-inch-drive 6-inch extension
• 3/8-inch-drive torque wrench rated 5-30 Nm
• Battery terminal cleaning brush
• Battery lifting strap rated 50 pounds minimum
• Chemical-resistant work gloves
• ANSI-rated safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• BCI Group 124R 12-volt battery matching or exceeding the original CCA rating - Qty: 1
• Battery terminal protectant - Qty: 1

CCA means “cold cranking amps,” which measures the battery’s ability to start the engine in cold conditions. Match the group size, terminal orientation, and minimum CCA shown on the original battery label.

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📋 Before You Begin

• Park your Sonata on level ground, shift into Park, apply the parking brake, and open the hood.
• Switch off the lights, climate control, audio system, and ignition. Remove the smart key from the work area.
• Wait at least three minutes after switching off the ignition before disconnecting the battery.
• Record saved radio stations and personal settings because they may be erased.
• Do not close the trunk while the battery is disconnected unless the mechanical key is available.
• Confirm the replacement battery has its positive and negative posts in the same positions as the original.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Locate and inspect the battery

• Open the hood and locate the battery on the driver’s side of the engine compartment.
• Use your safety glasses and chemical-resistant gloves before handling it.
• Check for a swollen, cracked, leaking, or frozen case. If any are present, do not remove the battery yourself.

Step 2: Disconnect the negative cable

• Identify the negative terminal by its minus symbol and black cable.
• Use the 10mm socket and 3/8-inch-drive ratchet to loosen the negative terminal clamp nut.
• Lift the clamp straight off the post. Move it aside where it cannot spring back against the battery.
• Do not remove or pry on the sensor fitted to the negative cable.
• Never start with the positive terminal.

Step 3: Disconnect the positive cable

• Open the red protective cover over the positive terminal.
• Use the 10mm socket and 3/8-inch-drive ratchet to loosen the positive terminal clamp nut.
• Lift the clamp straight off the positive post and position it away from the battery.
• Do not allow the ratchet to touch body metal while it contacts the positive terminal.

Step 4: Remove the battery hold-down

• Locate the hold-down bracket at the lower front edge of the battery.
• Use the 12mm socket, 6-inch extension, and 3/8-inch-drive ratchet to remove its bolt.
• Lift out the bolt and hold-down bracket. Place them where they cannot fall into the engine compartment.

Step 5: Remove the old battery

• Fit the battery lifting strap securely around the battery. A lifting strap is a strong carrier that provides safer handles for a heavy battery.
• Lift the battery straight upward using both hands. Keep it level to prevent acid leakage.
• Set it upright on a stable, acid-resistant surface.

Step 6: Clean and inspect the mounting area

• Use the battery terminal cleaning brush to remove light corrosion from the inside of both cable clamps.
• Inspect the tray, hold-down bracket, cables, and terminal clamps for damage.
• Do not install the battery if a terminal clamp is cracked or cannot tighten securely.

Step 7: Install the replacement battery

• Use the battery lifting strap to lower the Group 124R battery squarely into the tray.
• Position it with the terminals oriented exactly like the original battery.
• Make sure the case sits flat and cannot rock in the tray.

Step 8: Reinstall the hold-down bracket

• Place the lower hold-down bracket against the battery base flange.
• Start the bolt by hand to avoid damaged threads.
• Use the 12mm socket, extension, and torque wrench to tighten the hold-down bolt to 8.8 Nm (78 in-lbs).
• Gently push the battery by hand. It must not slide or lift.

Step 9: Connect the positive cable

• Push the positive clamp fully down onto the positive battery post.
• Use the 10mm socket and torque wrench to tighten the clamp nut to 5.9 Nm (52 in-lbs).
• Apply a light coating of battery terminal protectant after the connection is tight.
• Close the red positive-terminal cover completely.

Step 10: Connect the negative cable

• Push the negative clamp fully down onto the negative battery post.
• Use the 10mm socket and torque wrench to tighten the clamp nut to 5.9 Nm (52 in-lbs).
• Apply a light coating of battery terminal protectant after tightening.
• Try to rotate each clamp by hand. Neither clamp should move.

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✅ After Repair

• Make sure all tools are removed from the engine compartment, then start the engine.
• Confirm the charging-system warning light turns off after the engine starts.
• Set the clock and restore saved audio preferences if they were erased.
• Initialize each automatic window if one-touch operation was lost: close the window fully, then hold the switch upward for several seconds.
• Drive normally while the engine and transmission control systems relearn their settings. Minor idle or shift changes may occur briefly.
• No scan-tool battery registration is required for your Sonata.
• Recycle the old lead-acid battery through the battery seller or an authorized recycling facility. Never place it in household waste.

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💰 DIY vs Shop Cost

Shop Cost: ₹9,000-₹17,000 (parts + labor)

DIY Cost: ₹7,500-₹14,000 (parts only)

You Save: ₹1,500-₹3,000 by doing it yourself!

Local labor and battery prices vary. This repair takes a shop approximately 0.3-0.5 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.