Why Your 2020 Dodge Charger Won't Start (Battery Diagnosis & AGM Swap)

How to Fix Battery Replacement

Replacing the battery in your 2020 Dodge Charger is a common maintenance task, but it can be more involved than you think, especially when dealing with modern electronics and AGM batteries. A dead or failing battery can manifest in frustrating ways, from a simple no-start to perplexing electrical glitches. As one owner, Blakjakz, shared after a surprisingly long run: "Had to change my battery yesterday Insane to me that the factory battery lasted nearly 11 years" (source). This guide will walk you through the symptoms, diagnosis, and replacement process based on real owner experiences.

Symptoms

The signs of a failing battery in this vehicle often go beyond just a slow crank. Owners report a range of electrical issues that can be confusing to diagnose. The most common symptom is a no-start condition where the engine fails to turn over. You might hear a single loud click or a series of clicks from the starter solenoid, but the engine doesn't crank. As SleepyWulfy described: "Went to go start the car and it didn't crank over, I just heard a click and maybe 3 seconds later I heard another click. Red ETC light came on but then went away" (source).

Another cluster of symptoms involves what owners often call "electrical gremlins." This can include intermittent warning lights on the dashboard, such as the check engine light or the Electronic Throttle Control (ETC) light flashing briefly during a failed start. You might experience flickering interior lights, unresponsive infotainment screens, or erratic behavior from power accessories. These issues arise because the vehicle's numerous computers require stable, precise voltage to operate correctly; a weak battery cannot provide this.

In some cases, the problem may seem to fix itself mysteriously, only to return later. This intermittent nature is a classic hallmark of a battery with a failing cell or poor internal connection. One owner from a different model noted a similar experience: "On a whim, I decided to try to start my car again, and that time it worked! Very odd, and I thought it might be a fluke" (source). Furthermore, a chronically undercharged battery due to short-trip driving can lead to a slow, progressive failure. As Zayadur explained, short drives prevent the alternator from fully replenishing the charge used to start the car, leading to a state of constant drain: "If you don’t go on frequent 20+ minute drives... battery drains over time" (source).

Most Likely Cause

The primary cause of premature battery failure and related electrical issues, according to owner data, is chronic undercharging due to insufficient drive cycles. Modern vehicles, especially performance-oriented models like the Charger, have significant parasitic draw from computers, security systems, and connected features. The alternator needs adequate time at operating RPM to recharge the battery after the substantial energy used during engine start-up.

When the vehicle is used primarily for short trips—common in daily commuting—the alternator does not have enough time to fully replenish the battery. This leads to a gradual state of discharge. Over time, this sulfates the battery plates, permanently reducing capacity and eventually leading to failure. This is not a defect but a consequence of usage patterns. As the same owner elaborated, this lifestyle can affect more than just the battery: "It’s not the worst idea but it’s also not ideal for your car. If you don’t go on frequent 20+ minute drives to allow oil to circulate, burn off residue, etc. things like sludge form and fuel system can gum up, battery drains over time" (source). While a faulty alternator or a parasitic draw from an aftermarket accessory (like a hardwired dashcam) can also be culprits, the root cause often traces back to an energy deficit created by driving habits.

How to Diagnose

Proper diagnosis ensures you don't replace a good battery or miss a different underlying problem. You'll need a digital multimeter and possibly a battery load tester.

Step 1: Visual Inspection. Open the hood and check the battery terminals for severe corrosion (a white, blue, or green crusty substance). Inspect the battery case for any cracks, bulges, or leaks. Ensure the terminal connections are tight and secure. A poor connection can mimic a dead battery.

Step 2: Resting Voltage Test. With the vehicle off and all doors closed for at least an hour, use your multimeter set to DC Volts. Touch the red probe to the positive terminal and the black probe to the negative terminal. A fully charged AGM battery should read between 12.6 and 12.8 volts. A reading below 12.4 volts indicates a state of discharge; below 12.0 volts suggests a deeply discharged or failing battery.

Step 3: Cranking Voltage Test. This is the most telling test. Have a helper attempt to start the car while you monitor the multimeter. Watch the voltage during cranking. It should not drop below 10.0 volts for an AGM battery. If it plunges to 9 volts or lower, the battery lacks the necessary cold cranking amps (CCA) and is likely failing. This test often reveals the "click no-crank" issue owners describe.

Step 4: Charging System Test. With the engine running and all electrical loads off (headlights, A/C, radio), measure the voltage at the battery terminals. It should read between 13.8 and 14.8 volts. This confirms the alternator is providing charge. If the voltage is higher (over 15 volts), the alternator may be overcharging and cooking the battery. If it's lower (under 13.5 volts), the alternator may not be charging sufficiently.

Step 5: Check for Parasitic Draw. This is more advanced. Set your multimeter to measure amps (10A scale initially). Disconnect the negative battery cable. Connect the multimeter in series between the negative battery post and the disconnected cable. With the car fully asleep (all doors closed, key fob away, wait 20-30 minutes), the parasitic draw should be less than 50 milliamps (0.050A). A higher draw indicates something is staying on and draining the battery. As one owner learned the hard way: "XD had a dashcam that would kill the battery overnight and I’d never know why til I read my ownERS MANUAL" (source).

Step-by-Step Fix

Replacing the battery in a 2020 Charger requires care to avoid triggering electrical issues or losing memory in modules.

Step 1: Safety First. Park on a level surface, set the parking brake, and turn the ignition OFF. Put on safety glasses and gloves. Battery acid can be corrosive.

Step 2: Identify Battery Type. Your Charger likely uses an Absorbent Glass Mat (AGM) battery, which is standard for vehicles with Start-Stop technology or high electrical demand. Do not replace an AGM battery with a traditional flooded lead-acid battery.

Step 3: Locate the Battery. In the 2020 Charger, the battery is located in the trunk on the driver's side, behind a trim panel. You may need to remove the panel or carpeting to access it.

Step 4: Disconnect the Negative Terminal First. Using a 10mm wrench or socket, loosen the nut on the negative (-) terminal clamp. Carefully twist and lift the clamp off the post and secure it away from the battery. Taping the end is a good practice. Always disconnect negative first to prevent a short circuit if your tool touches ground.

Step 5: Disconnect the Positive Terminal. Repeat the process for the positive (+) terminal.

Step 6: Remove the Battery Hold-Down. There will be a bracket or strap securing the battery. Remove the fastener (often a 13mm bolt) and set the hold-down aside.

Step 7: Remove the Old Battery. Batteries are heavy (35-50 lbs). Carefully lift the battery straight out of the tray and place it on the ground. Check the tray for debris or corrosion and clean it with a baking soda/water solution if needed (neutralizes acid). Rinse and dry thoroughly.

Step 8: Install the New Battery. Place the new AGM battery into the tray, ensuring it is oriented correctly (terminals on the correct sides).

Step 9: Secure the Battery. Reinstall the hold-down bracket or strap and tighten securely. The battery should not move.

Step 10: Connect the Positive Terminal First. Slide the positive terminal clamp onto the post and tighten the nut firmly. Then, connect the negative terminal and tighten. A light coating of dielectric grease on the terminals can prevent future corrosion.

Step 11: Power-On and Relearn. Once connections are secure, close the trunk and enter the vehicle. You may need to reset the power windows (roll them all the way down, then all the way up) and the sunroof. The radio may require a security code (check your manual or a card in your glove box). The engine computer will need to relearn idle trim; simply start the car and let it idle for a few minutes, then drive normally for about 10 miles. As one owner, REVN302, cautioned about new batteries: "I know you just replaced it but it could be a bad cell in the new battery. I’ve seen it happen before" (source). It's wise to perform a voltage test on the new battery after installation.

Parts and Tools Needed

• Battery: AGM (Absorbent Glass Mat) battery, Group Size H7 (or as specified for your trim level). Common brands include Mopar (OEM), Odyssey, DieHard Platinum, or Interstate AGM. Confirm the Group Size and Cold Cranking Amps (CCA) rating in your owner's manual.
• Basic Hand Tools: 10mm wrench or socket for terminals. 13mm socket/wrench for the hold-down bracket. Socket wrench set.
• Safety Gear: Safety glasses, chemical-resistant gloves.
• Cleaning Supplies (Optional): Wire brush or battery terminal cleaner, baking soda, water, small brush, dielectric grease.
• Diagnostic Tools: Digital multimeter (essential for verification).

Real Owner Costs

Battery replacement costs vary significantly between DIY and professional service, primarily due to the cost of the AGM battery itself.

DIY Cost: The price is almost entirely the battery. A quality AGM battery for the Charger typically ranges from $220 to $350 at parts stores. If you need basic tools, add $20-$50. Your total out-of-pocket cost is the battery price. As Blakjakz's experience shows, the factory battery can last many years, making this a long-term investment.

Professional Service Cost: Taking your vehicle to a dealership or independent shop adds labor. Expect 0.5 to 1.0 hours of labor. Labor rates vary from $100/hour at an independent shop to $180/hour or more at a dealership.

• Dealership Total: Battery ($250-$400) + Labor ($90-$180) + Shop Supplies/Fees = $400 to $650+.
• Independent Shop Total: Battery ($220-$350) + Labor ($50-$100) = $270 to $450.

The premium at the dealership often includes a genuine Mopar battery, a full system test, and registration of the new battery to the vehicle's computer, which is sometimes required for proper charging system management. The DIY route saves a minimum of $150.

Prevention

Preventing premature battery failure revolves around maintaining a full state of charge and reducing unnecessary drain.

1. Take Longer Drives: This is the single most effective prevention tip. Make a conscious effort to take a drive of at least 20-30 minutes once a week, especially if your daily commute is short. This allows the alternator to fully recharge the battery. As Zayadur advised for overall health: "go on longer drives during downtime to keep her healthy!" (source).
2. Use a Battery Maintainer: If you drive infrequently, take short trips only, or plan to store the vehicle for more than two weeks, invest in a smart battery maintainer (trickle charger). Plug it into a wall outlet and connect it to the battery terminals (often via leads that can be permanently attached to the battery for easy access). This will keep the battery at 100% charge without risk of overcharging.
3. Minimize Parasitic Draw: Be mindful of aftermarket accessories. If you install a dashcam, radar detector, or other device, ensure it is wired through a switched fuse or has a built-in low-voltage cutoff to prevent it from draining the battery when the car is off.
4. Terminal Maintenance: Once a year, check battery terminals for corrosion. Clean any buildup with a wire brush and apply a small amount of dielectric grease to the posts to prevent future corrosion and ensure a good electrical connection.
5. Regular Testing: Have your battery and charging system tested for free at most auto parts stores once a year, preferably before winter. Catching a weak battery early can save you from a no-start situation.

What Owners Say

Real experiences from DODGE owners:

Success Stories

"This was about the time that it was the first and last time in the proceeding and following week that it would be above freezing. On a whim, I decided to try to start my car again, and that time it worked!" — dirkadirka666 (source)

"On a whim, I decided to try to start my car again, and that time it worked! Very odd, and I thought it might be a fluke." — dirkadirka666 (source)

Owner Experiences

"Had to change my battery yesterday Insane to me that the factory battery lasted nearly 11 years" — Blakjakz (source)

"It’s not the worst idea but it’s also not ideal for your car. If you don’t go on frequent 20+ minute drives to allow oil to circulate, burn off residue, etc. things like sludge form and fuel system can gum up, battery drains over time." — Zayadur (source)

"Change oil frequently, like every 3,000 miles. Use a good quality fuel system cleaner every 3,000 miles (probably unnecessary if you always go to a name brand gas station), warm up your car for a couple of minutes before driving, keep an eye on the battery’s health, and go on longer drives during downtime to keep her healthy!" — Zayadur (3,000 miles) (source)

FAQ

Q: How long does it take to replace the battery? A: For a first-time DIYer, the physical replacement takes about 30-45 minutes, accounting for accessing the trunk-mounted battery, careful disconnection, and cleanup. The additional time for systems to relearn (windows, idle) happens during your first drive. A professional technician can typically complete the job in under 30 minutes.

Q: Can I drive with a weak battery? A: It is not recommended. A weak battery forces the alternator to work harder to compensate, which can lead to premature alternator failure—a much more expensive repair. More critically, a battery that fails completely will leave you stranded. Intermittent electrical glitches from a weak battery can also affect safety systems and drivability.

Q: Is battery failure a common issue on the 2020 Charger? A: Battery failure itself is not a model-specific defect; it's a wear item. However, the prevalence of short-trip driving and the high electrical load of modern features make any modern car susceptible to premature battery failure if not properly maintained. The factory batteries, as one owner found, can be quite durable, lasting up to a decade with proper charging cycles.

Q: DIY vs mechanic - what's recommended for a battery replacement? A: For a straightforward battery swap, DIY is highly recommended for anyone comfortable with basic hand tools. The process is simple, and you save a significant amount on labor. The key is ensuring you purchase the correct AGM battery. The main reason to use a mechanic is if you are unable to diagnose the problem confidently (to rule out alternator or parasitic draw) or if you are uncomfortable handling the electrical components. Some owners prefer a shop for the system test and battery registration.

Q: Do I need to "code" or "register" the new battery to the car? A: Some modern vehicles with intelligent battery sensors (IBS) require the vehicle's computer to be told a new battery has been installed so it can adjust its charging strategy. For the 2020 Dodge Charger, this process varies. Some models/years may require a simple reset procedure (often involving a specific sequence with the ignition and headlights), while others may require a scan tool. Consult your owner's manual or a service manual for the specific procedure. Many parts stores can perform this reset if needed.

Q: What if I replace the battery and the car still won't start? A: If you've installed a new, properly charged AGM battery and you still get a "click" but no crank, the problem likely lies elsewhere. The next most common culprits are a faulty starter motor (a common suspicion among owners), a bad starter relay, or a poor connection in the heavy-gauge cables between the battery and starter. A professional diagnosis with a multimeter to check for voltage drop at the starter during a crank attempt is the next logical step.