🔧 Ascent - Battery Replacement

This is a straightforward job. Disconnect the negative terminal first, remove the hold-down bracket, swap the battery, then reconnect the negative terminal last.

The parts sidebar now shows matching batteries and battery-service supplies. The Odyssey Performance Group 35 AGM battery is the strongest catalog-listed vehicle-specific option at $361.99, but confirm its dimensions and terminal layout against the battery currently installed before ordering.

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

---

⚠️ Safety & Precautions

• ⚠️ Switch off the ignition and remove the key from the vehicle.
• ⚠️ Keep sparks, cigarettes, and open flames away from the battery.
• ⚠️ Never allow a metal tool to touch a battery terminal and body metal simultaneously.
• ⚠️ Disconnect negative first and reconnect negative last. This reduces short-circuit risk.
• ⚠️ Batteries are heavy and contain corrosive acid. Lift with both hands and keep the battery upright.
• ⚠️ Don’t remove the battery sensor from the negative cable unless it’s necessary.

---

🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 12mm socket
• 6-inch socket extension
• 3/8-inch-drive ratchet
• Inch-pound torque wrench
• Battery terminal puller (specialty)
• Battery terminal cleaning brush
• Battery lifting strap (specialty)
• Insulated work gloves
• Safety glasses

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Group 35 12-volt starting battery - Qty: 1
• Battery terminal protector washer set - Qty: 1
• Battery terminal cleaner spray - Qty: 1

Use a battery with the same post orientation and at least the original cold-cranking-amp rating. An AGM battery is a solid upgrade for frequent short trips and heavy accessory use. Buy once, cry once.

---

📋 Before You Begin

• 📋 Park your Ascent on level ground, select Park, and apply the parking brake.
• 📋 Lower a window so you can enter the vehicle if the power locks behave unexpectedly.
• 📋 Switch off the lights, climate control, audio system, and all accessories.
• 📋 Open the hood and wait at least one minute after switching off the ignition.
• 📋 Take a phone photo of the battery orientation and cable routing.
• 📋 Check that the replacement battery’s positive post matches the original position.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Locate and inspect the battery

• Find the battery in the engine compartment.
• Identify the negative terminal marked “−” and the positive terminal marked “+”.
• Check the cable routing and note the electrical sensor attached to the negative cable.

Step 2: Disconnect the negative terminal

• Use the 10mm socket and ratchet to loosen the negative terminal clamp.
• Lift the clamp straight off the negative post. Use the battery terminal puller if it’s stuck.
• Move the cable aside so it can’t spring back onto the post.
• Don’t twist or pry against the battery sensor.

Step 3: Disconnect the positive terminal

• Open the red positive-terminal cover.
• Use the 10mm socket to loosen the positive terminal clamp.
• Lift the clamp from the post and position it where it can’t touch metal.

Step 4: Remove the battery hold-down

• Use the appropriate 10mm or 12mm socket, extension, and ratchet to loosen both hold-down nuts evenly.
• Remove the top bracket and carefully unhook the two retaining rods.
• Keep the rods upright so they don’t fall into the engine compartment.

Step 5: Remove the old battery

• Attach the battery lifting strap or grasp the battery’s built-in handle.
• Lift the battery straight upward with both hands.
• Keep it upright and place it on a stable surface.
• Don’t lift it by the terminals.

Step 6: Clean and inspect the tray

• Wear safety glasses and insulated work gloves.
• Remove loose debris from the battery tray.
• Use the battery terminal cleaner spray and cleaning brush on corrosion around the cable clamps.
• Replace a swollen, cracked, or acid-damaged cable instead of reinstalling it.

Step 7: Install the replacement battery

• Lower the new battery squarely into the tray with the posts matching the original orientation.
• Make sure the battery sits flat and no cable is trapped beneath it.
• Reinstall the retaining rods and top hold-down bracket.
• Tighten the hold-down nuts evenly with the inch-pound torque wrench to 3.5 N·m (31 in-lb). Subaru lists this torque for its battery tie-down hardware. techinfo.subaru.com)
• Confirm the battery can’t slide or rock. Don’t overtighten and crush the case.

Step 8: Connect the positive terminal

• Install the red protector washer over the positive post if using the washer set.
• Push the positive clamp fully down onto the post.
• Use the 10mm socket to tighten the clamp until it can’t rotate by hand.
• Close the red terminal cover.

Step 9: Connect the negative terminal

• Install the dark protector washer over the negative post if using the washer set.
• Push the negative clamp fully down onto the post.
• Support the battery sensor with one hand while tightening its ground-terminal connection.
• If that sensor connection was loosened, use the inch-pound torque wrench and tighten it to 7.5 N·m (66 in-lb). Subaru’s Ascent battery procedures specifically warn that the sensor must be supported while tightening. subaru.oemdtc.com
• Confirm neither terminal clamp can twist by hand.

---

✅ After Repair

• ✅ Start the engine and confirm that the charge warning light goes out.
• ✅ Check that the clock, radio presets, power windows, locks, liftgate, and seat memory operate normally.
• ✅ Turn the steering wheel slowly from center toward each side, then return it to center.
• ✅ Let the engine idle for several minutes without heavy electrical loads.
• ✅ If a window loses one-touch operation, close it fully and hold the switch upward for several seconds.
• ✅ Recheck both terminals and the hold-down after a short drive.
• ✅ Return the old battery to a battery retailer or authorized recycling center. Never place it in household waste.

---

💰 DIY vs Shop Cost

Shop Cost: Approximately $250–$500 (parts + labor)

DIY Cost: Approximately $175–$425 (parts only)

You Save: Approximately $50–$150 by doing it yourself!

Local labor and battery prices vary. This repair generally takes a shop approximately 0.3–0.5 hour.

---

🎯 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.