2020 Peterbilt 579 Battery Size & Group

Quick Answer

• BCI Group Size: Group 31 (typically 3-4 batteries in parallel)
• CCA Rating: 925-1150 CCA per battery (for a total of 2775-4600 CCA in a multi-battery setup)
• Reserve Capacity: 170-200 minutes per battery
• AGM vs. Flooded: Flooded (lead-acid) is standard and generally recommended for cost-effectiveness and durability in this application. AGM can be used but offers fewer advantages in a series/parallel heavy-duty setup.
• Terminal Layout: Typically SAE posts with threaded studs for heavy-duty cable connections.
• Physical Dimensions: Each Group 31 battery is approximately 13" L x 6.8" W x 9.4" H
• Dual-Battery Setup: The 2020 Peterbilt 579 typically utilizes a multi-battery setup of three to four Group 31 batteries in parallel to meet the substantial power demands of its diesel engine and auxiliary systems.

Replacement Battery Options

Finding direct part numbers for Peterbilt 579 batteries can be tricky as manufacturers often list them by group size. Here are common heavy-duty battery brands and what you'd look for:

• Interstate: MTZ-31 (or similar Group 31 deep cycle/starting battery)
• Optima: Optima doesn't offer a direct Group 31 size. Their YellowTop D31A or D31T could potentially be used if you prefer AGM, but it would require careful consideration of total CCA and RC requirements for the entire bank.
• DieHard: Platinum Commercial Group 31 (or similar heavy-duty truck battery)
• Odyssey: 31-PC2150S (or similar Group 31, often a premium AGM option)
• ACDelco: 31P-925 (or similar Group 31 heavy-duty battery)

AGM vs. Flooded — Which Does This Vehicle Need?

The 2020 Peterbilt 579 can utilize either AGM (Absorbed Glass Mat) or traditional flooded lead-acid batteries, but flooded batteries are typically the standard and often more practical choice for several reasons:

• Cost-Effectiveness: Flooded lead-acid batteries are significantly less expensive upfront, which is a major factor when replacing three or four batteries.
• Durability and Vibration Resistance: Modern heavy-duty flooded batteries are designed to withstand the harsh vibrations and demands of commercial trucking.
• Amp-Hour Capacity: Flooded batteries often provide excellent amp-hour capacity per dollar, essential for powering auxiliary systems during rest stops.
• Temperature Performance: Both types perform well in extreme temperatures, but flooded batteries have a long-standing track record in heavy-duty applications.

AGM batteries offer benefits like spill-proof design, faster recharging, and better deep-cycle performance, but these advantages are often less critical in a multi-battery starter/house bank for a heavy truck. The cost premium for AGM might not translate to a substantially longer service life or better performance given the vehicle's design and usage.

Post-Installation Relearn / Reset Procedure

While the Peterbilt 579, like most heavy-duty trucks, doesn't have the extensive "relearn" procedures found in some modern passenger vehicles, there are a few important steps after battery replacement to ensure proper operation:

1. Engine ECM/TCM Reset (Soft Reset): After reconnecting the new batteries, turn the ignition key to the "ON" position for 30-60 seconds without starting the engine. This allows the Engine Control Module (ECM) and Transmission Control Module (TCM) to re-establish communication and perform basic self-checks. Then, start the engine.
2. Radio/Infotainment System: You may need to re-enter any security codes for the radio or infotainment system (if applicable). Refer to your Peterbilt owner's manual for specific instructions.
3. Clock and Trip Computer: Reset the clock and any trip computer data that may have been lost.
4. Automatic Windows (if equipped): Some trucks with automatic power windows may require a simple reset. Typically, this involves holding the window down switch for a few seconds after it reaches its lowest point, then holding the up switch for a few seconds after it reaches its highest point.
5. Fault Codes: If any "low voltage" or "battery disconnect" fault codes appeared before battery replacement, they should clear themselves after a few drive cycles. If persistent codes remain, a diagnostic tool may be needed to clear them.

Always ensure connections are clean and tight. Loose connections are a common cause of electrical issues.

Signs of a Failing Battery

Recognizing a failing battery in a heavy-duty truck is crucial to avoid costly downtime. Look out for these symptoms:

• Slow Cranking: The most obvious sign. The engine turns over sluggishly, especially during cold starts.
• Dim Lights/Flickering Dash: Headlights, interior lights, or the dashboard flickering when trying to start the truck.
• Warning Lights: A battery warning light or "low voltage" message on the dashboard.
• Electrical Component Malfunctions: Auxiliary systems like the bunk heater, air conditioning, or infotainment system acting erratically or not working properly without the engine running.
• Corrosion on Terminals: Excessive white or blue powdery corrosion around the battery terminals can indicate a poor connection or internal battery issues.
• Swollen or Bulging Battery Case: A visually noticeable swelling of the battery case is a clear sign of internal damage, often due to overcharging or extreme heat.
• Frequent Jump Starts: Needing to jump-start the truck regularly is a definitive indicator of a dying battery bank.
• Age: Heavy-duty truck batteries typically last 3-5 years, depending on usage and climate. If your batteries are older than this, even without obvious symptoms, it's wise to have them tested.

Common Battery Issues for This Generation (2020 Peterbilt 579)

The Peterbilt 579, like other modern Class 8 trucks, places significant demands on its electrical system. Common battery issues often stem from:

• Parasitic Draws: Modern trucks have numerous electronic control units (ECUs) and convenience features that can draw power even when the truck is off. If left unattended for extended periods, this can slowly discharge the batteries, leading to reduced lifespan.
• Vibration Damage: Constant road vibrations can shorten battery life, especially if batteries are not properly secured in their trays. Loose batteries suffer internal damage more quickly.
• Alternator/Charging System Failures: A failing alternator (or multiple alternators in some setups) will not adequately charge the batteries, leading to continuous undercharging and premature failure.
• Idling Practices: Prolonged idling, particularly with heavy auxiliary loads (HVAC, APU, inverter), can stress the batteries and charging system if the charge rate isn't sufficient to keep up with the draw.
• Poor Maintenance: Neglecting to clean battery terminals, check water levels (in flooded batteries), or inspect cables can lead to resistance and charging problems.
• Extreme Temperatures: Both extreme heat and extreme cold can reduce battery efficiency and lifespan. Cold weather increases the CCA requirements, while heat accelerates internal chemical reactions.

Regular testing of the entire battery bank and charging system is crucial for longevity.

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