2018 International LT Battery Size & Specs: A Mechanic's Guide

As an ASE-certified master technician, I know that keeping a Class 8 heavy-duty truck on the road requires serious starting power and electrical endurance. The 2018 International LT, whether equipped with the Cummins X15 or the Navistar A26 engine, relies heavily on a robust battery bank. With sleeper cabs running APUs, inverters, refrigerators, and climate control, your battery choice is critical to avoiding downtime and expensive service calls.

Here is the complete battery specification guide for the 2018 International LT.

Quick answer

• BCI Group Size: Group 31
• Multi-Battery Setup: Yes. The 2018 International LT typically requires a four-battery setup wired in parallel to achieve 12 volts with massive cranking and reserve power. (Some day cabs may use three; extreme sleeper configurations may use up to eight with an isolated hotel bank).
• Cold Cranking Amps (CCA): 925 to 1,000+ CCA per battery (providing roughly 3,700 to 4,000+ total CCA combined).
• Reserve Capacity (RC): 190 to 200+ minutes per battery.
• AGM vs Flooded: AGM (Absorbent Glass Mat) is highly recommended, especially for sleeper cabs with heavy "hotel loads." Flooded lead-acid is acceptable for basic day cabs.
• Terminal Layout: Typically 3/8"-16 threaded stud terminals (centered), though SAE post variations exist depending on your exact cable harness setup. Always verify your current cable ends before purchasing.
• Physical Dimensions: Approximately 13.0" L x 6.8" W x 9.4" H (per battery).

Replacement battery options

When replacing the batteries in your International LT, you must replace all of them at the same time. Mixing old and new batteries will cause the older units to drain the new ones, leading to premature failure. Here are some of the most popular, heavy-duty Group 31 replacement options:

• Odyssey Extreme Series (Part # ODX-AGM31): An absolute powerhouse for heavy-duty applications. Provides 1,150 CCA and deep-cycle capabilities perfect for sleeper cab hotel loads.
• Optima YellowTop (Part # D31T): A dual-purpose AGM battery offering 900 CCA and excellent vibration resistance, featuring 3/8" stainless steel stud terminals.
• Interstate Workaholic Heavy-Duty (Part # 31-MHD): A reliable flooded lead-acid option providing 950 CCA. Great for day cabs that do not have extensive key-off electrical draws.
• DieHard Platinum AGM (Group 31): Offers premium AGM technology with excellent vibration resistance and deep cycling for inverters and APUs.
• ACDelco Heavy Duty AGM (Part # 31AGM): Provides consistent starting power (925 CCA) and is built to withstand the rigorous vibrations of a Class 8 chassis.

AGM vs flooded — which does this vehicle need?

For a 2018 International LT sleeper cab, AGM batteries are strongly required. Long-haul drivers rely on power inverters, microwaves, CPAP machines, televisions, and heavy HVAC systems while the engine is off. These "hotel loads" deeply discharge the batteries. AGM batteries are designed to handle repeated deep discharging and recharging without degrading the internal plates. They also charge significantly faster than flooded batteries and handle the extreme vibrations of a semi-truck chassis much better.

If your International LT is a day cab used for local delivery without a high-draw liftgate or inverter, traditional flooded heavy-duty batteries (like the Interstate 31-MHD) will save you money while providing plenty of starting power.

Post-installation relearn / reset procedure

Replacing the battery bank on an International LT involves managing multiple heavy cables, but the electronic reset is relatively straightforward:

1. Low Voltage Disconnect (LVD) Reset: The LT is equipped with an LVD system to prevent the batteries from draining so far that the truck won't start. After replacing dead batteries, the LVD module should automatically recognize the new voltage. However, if interior sleeper accessories do not power on, you may need to cycle the ignition key or press the manual LVD override/reset button (usually located on the dash or near the sleeper control panel).
2. Engine Control Module (ECM): The Cummins or Navistar ECM will power up normally. No specialized scan tool relearn is required just for a battery swap, but you should turn the key to the ON position for 30 seconds before cranking to allow the throttle body and sensors to run their sweep checks.
3. Clock and Radio: You will need to reset the clock and any preset radio stations.

Signs of a failing battery

• Low Voltage Disconnect Tripping: If your truck's LVD system shuts off your sleeper accessories shortly after turning off the engine, your battery bank has lost its reserve capacity.
• APU Running Constantly: If your Auxiliary Power Unit (APU) is cycling on much more frequently than normal to charge the batteries, the bank is failing.
• Slow Engine Crank: The Cummins X15 and Navistar A26 take massive torque to turn over. A noticeable drag or hesitation during the starting sequence is a major red flag.
• Dimming Lights: Dashboard or headlight flickering when heavy electrical loads (like the HVAC blower) kick on.

Common battery issues for this generation

The most frequent battery issue on the 2018 International LT isn't always the batteries themselves, but the crossover cables. Because there are four batteries wired in parallel, the short jumper cables connecting the positive and negative terminals are highly susceptible to corrosion and vibration damage. A loose or corroded jumper cable increases electrical resistance, forcing one or two batteries to do all the work while the others sit idle. This destroys the overworked batteries very quickly. Always clean the cable ends thoroughly and apply a dielectric grease or battery terminal protector when installing your new bank.

Additionally, parasitic draws from aftermarket telematics or improperly wired inverters are common on the LT. Always wire heavy accessories to the main distribution studs, not directly to a single battery post, to ensure the entire bank is drawn down and charged evenly.

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