The 2020 GMC Sierra uses a 12-volt automotive battery; the exact group size and whether a conventional flooded lead-acid or an AGM battery is required depend on the engine and options. To be sure, check the battery label, the owner's manual, or a VIN-specific GM parts lookup for the precise spec.
In this article, we break down how to identify the correct battery for your Sierra, describe the options you might encounter, and lay out safe steps for replacing it.
Understanding the 2020 Sierra Battery Requirements
Most Sierra models use a standard 12-volt battery, but the physical group size and battery type can vary by engine and equipment. If your truck has the stop-start system or higher electrical demand, GM often specifies an AGM (absorbed glass mat) battery for durability and better cold-crank performance. Always verify the exact spec for your VIN by checking the battery sticker, the owner's manual, or a GM Parts lookup for your exact configuration.
Below are factors that help determine the right battery for your truck.
- Look for the Group Size and CCA rating on the battery label. The label tells you the exact group size the battery fits and the minimum cold-cranking amps (CCA) required for reliable starting.
- Check the owner's manual or a GM parts catalog using your VIN to confirm whether the OEM battery is a conventional flooded battery or an AGM battery.
- Determine whether your truck is equipped with the start-stop system (auto start/stop). Start-stop-equipped models commonly use AGM batteries because they handle frequent restarts and high electrical loads better than conventional flooded batteries.
- Ensure the replacement battery matches the battery tray fitment and terminal configuration (positive/negative locations and post sizes).
- Consider choosing a battery with equal or greater CCA and reserve capacity (RC) than the OEM rating for reliability, especially in cold climates or heavy-use conditions.
In all cases, use the exact Group Size and CCA values specified for your Sierra. If in doubt, consult a dealer or an automotive parts retailer with your VIN.
Common Battery Characteristics for the 2020 Sierra
Here are the key features to understand when selecting a replacement:
- Battery type: Flooded lead-acid (conventional) or AGM, depending on equipment and options including start-stop.
- Group size: Physical size and terminal layout must match the battery tray and posts.
- CCA rating: Minimum cold-cranking amps required to start the engine in cold weather; higher is acceptable but must fit the tray and electrical system.
- RC (reserve capacity): The duration the battery can run essential systems without engine running; higher RC can help in heavy electrical load situations.
- Warranty: Most replacement batteries come with 2-4 year warranties; AGM batteries often have similar warranties when used as OEM-equivalent replacements.
The exact specifications for your Sierra should come from the vehicle’s battery label or the VIN-based GM documentation. If you’re replacing, aim to match or exceed the OEM rating and ensure the fit and terminals align with your truck.
How to Replace a Battery on a 2020 GMC Sierra
Replacing a 12-volt battery in a Sierra is straightforward but requires care to avoid electrical shorts and acid exposure. Follow these steps or have a qualified technician do it if you’re unsure.
- Park on a level surface, engage the parking brake, and turn off all electrical accessories. Open the hood and locate the battery.
- Disconnect the negative cable first. Loosen the clamp with a wrench, then lift the cable end away from the terminal.
- Disconnect the positive cable next, using the same method.
- Remove the hold-down clamp or bracket securing the battery in the tray, then lift the old battery out of the tray.
- Clean the battery tray and tray contacts if corrosion is present. Use baking soda and water to neutralize any acid residue, then dry.
- Place the replacement battery in the tray, aligning the terminal posts with the correct sides. Reinstall the hold-down clamp or bracket securely.
- Reconnect the positive terminal first, then the negative terminal. Tighten the clamps to the manufacturer’s specified torque.
- Reconnect any electronic systems that require memory or resets, and start the engine to ensure proper operation. If the vehicle’s radio or other settings reset, follow the owner’s manual steps to restore them.
- Properly dispose of the old battery at a recycling facility or auto parts store that accepts used batteries.
Always wear eye protection and gloves when handling batteries, and avoid contact with battery acid. If your Sierra has start-stop or premium electrical features and you’re unsure which type of replacement to purchase, consult a dealer or parts professional.
Summary
The 2020 GMC Sierra requires a 12-volt automotive battery, with the exact group size, CCA, and whether it’s conventional flooded or AGM determined by the engine and options, especially the presence of start-stop. Always verify the specific specs for your VIN and replace with a battery that matches or exceeds those requirements, ensuring proper fit and terminal configuration. When in doubt, consult a dealer or professional installer to ensure optimal performance and warranty compliance.