🔧 Crosstrek - 12V Battery Replacement

You’ll be removing the old 12V battery from the engine bay and installing a new one. This is a simple job, but the order you disconnect/reconnect the battery cables matters to prevent sparks and electrical damage.

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

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⚠️ Safety & Precautions

• 🧤 Wear gloves and safety glasses—battery acid is corrosive.
• 🔥 Keep sparks/flames away; batteries can vent flammable gas.
• 🔌 Always disconnect the negative (-) terminal first, reconnect it last.
• ⚡ Do not allow a tool to touch battery positive and metal body parts at the same time.
• 🔑 Key OFF and remove the key before starting.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm combination wrench
• 10mm socket
• 3/8" ratchet
• 3" socket extension
• Battery terminal puller (specialty)
• Battery terminal cleaning brush
• Shop towels
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 12V car battery (Group Size 35) - Qty: 1
• Battery terminal anti-corrosion felt washers - Qty: 2
• Battery terminal protector spray - Qty: 1
• Battery terminal cleaning solution - Qty: 1

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📋 Before You Begin

• Park on level ground, shift to neutral, set the parking brake, and pop the hood.
• If you want to keep radio presets/clock, use a memory saver (a small device that powers the car through the OBD-II port while the battery is out). If you don’t have one, it’s okay—just expect settings to reset.
• Wait 2-3 minutes after key-off before disconnecting the battery to let modules “go to sleep.”

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Locate the battery and identify terminals

• The battery is in the engine bay. The negative (-) terminal usually has a black cable; the positive (+) usually has a red cover.
• Use safety glasses and nitrile gloves before touching terminals.

Step 2: Disconnect the negative (-) terminal first

• Use a 10mm wrench to loosen the negative terminal clamp nut.
• Wiggle the clamp up and off the post. If it’s stuck, use a battery terminal puller (specialty) (it presses the clamp off without damage).
• Tuck the negative cable to the side so it cannot spring back onto the post.

Step 3: Disconnect the positive (+) terminal

• Flip open/remove the red protective cover (if equipped).
• Use a 10mm wrench to loosen the positive terminal clamp nut, then lift the clamp off the post.
• Keep the positive cable end from touching metal parts.

Step 4: Remove the battery hold-down

• Use a 10mm socket, 3/8" ratchet, and 3" extension to remove the hold-down nuts/bolts.
• Lift the hold-down bracket off and set it aside.

Step 5: Remove the old battery

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

Step 6: Clean the terminals and tray

• Use a battery terminal cleaning brush to clean the inside of both cable clamps until shiny.
• If there’s corrosion on the tray, use shop towels and your battery terminal cleaning solution to wipe it up.
• Clean metal = better starting and charging.

Step 7: Install the new battery

• Place the new Group Size 35 battery in the tray in the same orientation as the old one.
• Reinstall the hold-down bracket using the 10mm socket, ratchet, and extension.
• Tighten the hold-down until the battery cannot move by hand. Do not crush the battery case.

Step 8: Reconnect the positive (+) terminal first

• Install one anti-corrosion felt washer on the positive post (if using).
• Push the positive clamp fully down onto the positive post.
• Use a 10mm wrench to tighten the clamp until it will not rotate on the post.
• Reinstall/close the red protective cover (if equipped).

Step 9: Reconnect the negative (-) terminal last

• Install one anti-corrosion felt washer on the negative post (if using).
• Push the negative clamp fully down onto the negative post.
• Use a 10mm wrench to tighten the clamp until it will not rotate on the post.
• Spray a light coat of battery terminal protector spray on both terminals.

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✅ After Repair

• Start the engine and confirm it cranks normally and the charging light is off.
• Reset the clock and radio presets (if they were lost).
• Let the engine idle for about 5 minutes with all accessories off (helps the idle re-learn after power loss).
• Recheck terminal tightness: clamps should not twist by hand.

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💰 DIY vs Shop Cost

Shop Cost: $180-$350 (parts + labor)

DIY Cost: $120-$250 (parts only)

You Save: $60-$100 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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