🔧 ES350 - 12V Battery Replacement

Your ES350’s 12-volt battery powers the computers, locks, lights, and starting system. Replacing it is straightforward, but you need to keep the trunk open and avoid shorting the terminals with tools.

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

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⚠️ Safety & Precautions

• 🛑 Keep metal tools away from the positive (+) terminal to prevent sparks/shorts.
• 🛑 Keep the smart key/fob at least 10+ feet away so the car stays “off.”
• 🛑 Do not slam the trunk while the battery is disconnected; keep it propped open.
• 🛑 Disconnect the negative (–) terminal first, reconnect it last.
• 🛑 Battery acid is corrosive—wear gloves and safety glasses.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 12mm socket
• 3/8" ratchet
• 6" socket extension
• Torque wrench (5-30 Nm range)
• Plastic trim removal tool
• Battery terminal brush
• Shop rags
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 12V battery (ES350 correct size/spec) - Qty: 1
• Battery terminal anti-corrosion spray - Qty: 1
• Battery terminal felt washers - Qty: 2

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📋 Before You Begin

• 🧰 Park on level ground, shift to Park, and set the parking brake.
• 🧰 Open the trunk and keep it open (don’t rely on power trunk features while working).
• 🧰 Turn off all loads: headlights, climate, radio, and unplug chargers.
• 🧰 Tip: Keep one window slightly open.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Access the battery in the trunk

• Use a plastic trim removal tool to remove the right-side trunk floor/side cover panel (work gently to avoid breaking clips).
• Use safety glasses and nitrile gloves before handling the battery.

Step 2: Disconnect the negative (–) terminal

• Use a 10mm socket with a 3/8" ratchet to loosen the negative terminal clamp nut.
• Twist and lift the negative cable off the battery post, then tuck it aside so it can’t spring back.
• Tip: Negative off first prevents accidental short.
• Reinstall spec (later): Torque to 5 Nm (44 in-lbs)

Step 3: Disconnect the positive (+) terminal

• Use a 10mm socket with a 3/8" ratchet to loosen the positive terminal clamp nut.
• Lift the positive cable off and cover it with a shop rag so it can’t touch metal.
• Reinstall spec (later): Torque to 5 Nm (44 in-lbs)

Step 4: Remove the battery hold-down

• Use a 12mm socket, 6" socket extension, and 3/8" ratchet to remove the battery hold-down fastener(s).
• Lift off the hold-down bracket and set it aside.
• Reinstall spec (later): Torque to 19 Nm (14 ft-lbs)

Step 5: Remove the old battery

• Carefully lift the battery straight up and out. Keep it level (batteries are heavy).
• Set it on the ground upright.

Step 6: Clean and prep the terminals

• Use a battery terminal brush to clean the inside of both cable clamps until the metal looks bright.
• Wipe with shop rags.
• Install battery terminal felt washers (one on each post) if you’re using them.

Step 7: Install the new battery and secure it

• Place the new battery into position exactly like the old one (posts oriented the same way).
• Reinstall the hold-down bracket using the 12mm socket, 6" socket extension, and 3/8" ratchet.
• Use a torque wrench (5-30 Nm range): Torque to 19 Nm (14 ft-lbs)

Step 8: Reconnect the terminals (positive first)

• Install the positive (+) cable first and tighten using a 10mm socket and 3/8" ratchet.
• Use a torque wrench (5-30 Nm range): Torque to 5 Nm (44 in-lbs)
• Install the negative (–) cable last and tighten using a 10mm socket and 3/8" ratchet.
• Use a torque wrench (5-30 Nm range): Torque to 5 Nm (44 in-lbs)
• Apply battery terminal anti-corrosion spray after everything is tight.

Step 9: Reinstall trunk trim

• Reinstall the trunk side/floor cover using the plastic trim removal tool to align and seat clips.

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✅ After Repair

• 🔎 Start the car and confirm normal cranking and no warning lights staying on.
• 🔎 Check that headlights, horn, locks, and trunk release work.
• 🔎 Reset one-touch windows: with the car ON, use the window switch to fully lower the window, then fully raise it and keep holding the switch for 2 seconds.
• 🔎 Re-set clock and radio presets as needed.

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💰 DIY vs Shop Cost

Shop Cost: $250-$450 (parts + labor)

DIY Cost: $160-$300 (parts only)

You Save: $90-$150 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.