2020 Jeep Grand Cherokee Battery Replacement: A Step-by-Step Guide

Problem Overview

Replacing a car battery might seem like a simple swap, but based on an analysis of 107 owner discussions, it's a task that can have significant ripple effects on your vehicle's modern electronic systems. A failing or new battery can cause issues ranging from radio presets and window memory loss to more serious problems like check engine lights and transmission relearning. The discussions frequently highlighted that a battery replacement isn't just about cranking power; it's a central electronic event for the car's computer network.

When It's Due

There is no fixed mileage interval for battery replacement, as lifespan depends heavily on climate, driving habits, and electrical load. However, most automotive batteries last between 3 to 5 years. Key signs it's time for a replacement include:

• Slow engine crank, especially in cold weather.
• The battery warning light illuminating on the dashboard.
• Needing frequent jump-starts.
• Visible corrosion or swelling of the battery case.
• Electronic gremlins, such as flickering lights or erratic computer behavior, which were noted in several discussions as a precursor to failure.

Parts and Tools Needed

Parts:

• New Battery: Ensure it matches the Group Size (physical dimensions), Cold Cranking Amps (CCA), and Reserve Capacity (RC) specified for your vehicle. An "AGM" (Absorbent Glass Mat) battery may be required if your car has start-stop technology.
• Battery Terminal Cleaner Tool or Wire Brush: For cleaning corrosion.
• Anti-Corrosion Washers or Gel: (Optional) To prevent future terminal corrosion.

Tools:

• Basic wrench or socket set (typically 10mm, but size varies).
• Safety glasses and gloves.
• Battery terminal puller (helpful for tight, corroded terminals).
• Memory saver device (highly recommended to preserve radio codes, presets, and computer memory).

Complete Guide

This guide emphasizes the electronic preservation steps that owners in the discussions found most critical.

Step 1: Preparation and Safety Park on a level surface, set the parking brake, and turn off the ignition. Put on your safety glasses and gloves. Battery acid is corrosive.

Step 2: Preserve Electronic Memory (The Critical Step) This is where most post-replacement issues originate. Connect a memory saver device to your vehicle's OBD-II port or cigarette lighter before disconnecting the old battery. This provides a temporary 12V source to keep the computer, radio, presets, and power window/seat memory alive. If you don't have a memory saver, be prepared to lose these settings and potentially need to relearn procedures.

Step 3: Disconnect the Old Battery Always disconnect the NEGATIVE (black, "-") terminal first, then the POSITIVE (red, "+") terminal. This prevents accidental short circuits. Loosen the terminal clamp bolts and use a terminal puller if they are stuck. Do not pry with a screwdriver.

Step 4: Remove the Old Battery Unfasten any hold-down clamp or bracket securing the battery. Carefully lift the battery out. Batteries are heavy—lift with your legs.

Step 5: Clean the Tray and Terminals Use a wire brush and a baking soda/water solution to clean any corrosion from the battery tray and the cable terminals. Rinse and dry thoroughly.

Step 6: Install the New Battery Place the new battery in the tray and secure it with the hold-down clamp. Connect the POSITIVE terminal first, then the NEGATIVE terminal.** Tighten securely, but do not overtighten. Apply anti-corrosion gel to the terminals if desired.

Step 7: Post-Installation Procedures Remove the memory saver. Start the vehicle and let it run. You will likely need to:

• Reset the clock and radio presets.
• Re-index power windows (often by holding the switch up for a few seconds after reaching the top).
• Relearn the sunroof or power seats.
• Drive the vehicle for a short period. In multiple discussions, owners reported that driving cycles allowed the computer to relearn fuel trim and transmission shift points, which can clear incidental codes like P0128 (Coolant Thermostat) or P0731 (Incorrect Gear Ratio) that appeared only due to the power loss.

Advice from Mechanics

• Diagnose, Don't Assume: If you're having starting issues, have the battery and alternator tested (often free at parts stores) before buying a new battery. A failing alternator will kill a new battery quickly.
• The "Computer Relearn" Drive: After replacement, take the car for a 15-20 minute drive with varied speeds. This allows the Engine Control Module (ECU) to recalibrate. Many transient error codes will clear on their own after a few drive cycles.
• Handle AGM Batteries with Care: If your car uses an AGM battery, it may require a specific charging profile. Using a standard charger incorrectly can damage it.
• Check the Cables: While you're there, inspect the battery cables for brittleness or internal corrosion. A bad cable can mimic a bad battery.

Cost Estimates

• DIY Cost: $100 - $300+ for the battery itself. Memory saver tools cost $20-$50. The DIY job is considered beginner-friendly, with the main risk being electronic memory loss without a saver.
• Professional Installation: $150 - $400+ total, including the battery and labor. Labor typically adds $30-$75. The primary benefits are a warranty on the installation, proper disposal of the old battery, and mechanics who have the tools and software to properly reset and recalibrate vehicle systems if needed.

Source Summary: This analysis is based on 107 owner discussions from Reddit and automotive forums.