ACDelco Auxiliary Battery – Secondary Power

★★★★★4.8/5· thousands of reviews

Our ACDelco auxiliary battery provides dependable secondary power for vehicles equipped with start-stop technology, advanced driver assistance systems, and heavy electrical loads. Engineered to OE specifications, this battery supports the growing electrical demands of modern vehicles without compromising primary starting power.

Designed for seamless integration with your vehicle’s existing electrical architecture, the ACDelco auxiliary battery ensures consistent performance across temperature extremes and demanding driving conditions. Whether you’re powering navigation systems, entertainment consoles, or safety features, our secondary power solution delivers the reliable voltage regulation your vehicle requires.

  • Absorbed Glass Mat (AGM) technology for superior charge acceptance and vibration resistance
  • Enhanced cycling capability supports frequent charge-discharge cycles in start-stop applications
  • Valve-regulated, spill-proof design allows flexible mounting positions
  • Low self-discharge rate maintains charge during extended storage periods
  • Temperature-resistant construction performs reliably from -40°F to 140°F
Absorbed Glass Mat (AGM) technology for superior charge acceptance and vibration resistanceEnhanced cycling capability supports frequent charge-discharge cycles in start-stop applicationsValve-regulated, spill-proof design allows flexible mounting positionsLow self-discharge rate maintains charge during extended storage periodsTemperature-resistant construction performs reliably from -40°F to 140°F
Build quality
Everyday use
Value
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AGM Technology & Construction

AGM Technology & Construction

The ACDelco auxiliary battery utilizes Absorbed Glass Mat technology, where electrolyte is suspended in fine fiberglass mat separators rather than free-flowing liquid. This advanced construction delivers exceptional vibration resistance—critical for secondary batteries often mounted in non-traditional locations like under seats or in cargo areas.

AGM design also provides superior charge acceptance compared to conventional flooded batteries, allowing the acdelco auxiliary battery to recover quickly during regenerative braking and idle periods. The valve-regulated sealed case prevents acid leakage and corrosion, eliminating the need for periodic water additions. Our manufacturing process ensures consistent plate density and compression for reliable performance throughout the battery’s service life.


Vehicle Compatibility & Applications

Vehicle Compatibility & Applications

Start-Stop System Support

Modern vehicles with automatic start-stop technology place unique demands on electrical systems. Our acdelco auxiliary battery is specifically engineered to handle the frequent cycling these systems require. When the engine shuts off at traffic lights, the auxiliary battery maintains power to essential systems including climate control, infotainment, and safety features.

Advanced Electrical Architecture

Luxury and high-performance vehicles often employ dual-battery configurations to separate starting loads from accessory demands. The ACDelco auxiliary battery integrates seamlessly with battery management systems that monitor voltage, temperature, and state of charge. This intelligent power distribution protects sensitive electronics while ensuring sufficient reserve capacity for engine restart under all conditions.


Performance Characteristics & Service Life

Performance Characteristics & Service Life

The cycling capability of our AGM auxiliary battery far exceeds conventional flooded designs, with the ability to withstand hundreds of partial discharge cycles without capacity loss. This durability is essential for vehicles that frequently operate electrical accessories with the engine off, from work trucks running power inverters to family vehicles entertaining passengers during stops.

Temperature extremes significantly impact battery performance, but the acdelco auxiliary battery maintains stable voltage output across a wide operating range. Cold-weather starting assistance remains reliable, while hot-climate operation benefits from reduced water loss and thermal stability. The low self-discharge rate means the battery retains charge during extended vehicle storage, typically losing less than 3% capacity per month at room temperature.


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ACDelco Smart Battery Charger
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What people are saying

4.8
★★★★★
Based on verified reviews
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M
Michael T.
Verified buyer
★★★★★
Perfect Replacement for My BMW
My 2018 BMW X5 needed an auxiliary battery replacement and this ACDelco unit fit perfectly under the rear seat. The start-stop system works flawlessly again and all my electrical accessories have stable power. Installation was straightforward with the right tools, and the quality matches the original equipment battery.
J
Jennifer K.
Verified buyer
★★★★★
Solved My Electrical Issues Completely
After experiencing dimming lights and slow accessory response, I replaced my failing auxiliary battery with this ACDelco unit. The difference was immediate—all my electrical systems now operate smoothly even with the engine off. The AGM construction gives me confidence it will last through our harsh winters.
D
David R.
Verified buyer
★★★★★
Excellent Quality for Start-Stop Systems
I’ve been using ACDelco batteries for years and this auxiliary battery continues that tradition of reliability. My Audi’s start-stop system cycles constantly in city traffic, and this battery handles the demands without issue. Three months in and voltage remains rock solid.
P
Patricia L.
Verified buyer
★★★★★
OE Quality at a Better Price
The dealership quoted me nearly double for an auxiliary battery replacement. This ACDelco battery meets the same specifications and has been performing perfectly in my Mercedes for six months. The sealed AGM design means no maintenance, which I appreciate.
R
Robert F.
Verified buyer
★★★★☆
Great Battery, Check Fitment Carefully
This auxiliary battery works wonderfully in my vehicle, but make absolutely sure you verify the group size and terminal configuration before ordering. Once I confirmed compatibility, installation was simple and performance has been excellent. My electrical accessories run smoothly and the start-stop system operates as designed.
S
Steven M.
Verified buyer
★★★★★
Handles Heavy Electrical Loads Perfectly
I run multiple aftermarket accessories in my truck including an inverter and auxiliary lighting. This ACDelco auxiliary battery provides the reserve capacity I need without draining my main starting battery. The AGM technology recovers quickly during driving and maintains voltage under load better than my previous battery.

Common Questions About ACDelco Auxiliary Batteries

The primary starting battery provides high-current power for engine cranking, while the auxiliary battery supports accessory electrical loads and start-stop system operations. In dual-battery vehicles, the auxiliary battery handles climate control, infotainment, and safety systems when the engine is off, preventing excessive discharge of the starting battery.

This separation of functions extends the life of both batteries and ensures reliable starting even when accessories have been operating with the engine off. The ACDelco auxiliary battery is specifically designed for the cycling demands of accessory loads rather than the high-current starting demands.

Common symptoms include warning messages on your dashboard indicating auxiliary battery issues, start-stop system malfunction, dimming interior lights when accessories are running, or slow response from power windows and infotainment systems. Many modern vehicles monitor auxiliary battery health through the battery management system.

If your vehicle is 4-6 years old and experiencing these symptoms, auxiliary battery replacement is likely needed. A professional battery test can measure voltage, internal resistance, and capacity to confirm whether the acdelco auxiliary battery requires replacement before complete failure occurs.

You can replace the auxiliary battery independently if testing confirms the primary starting battery remains healthy. However, if both batteries are similar in age and the vehicle has experienced charging system issues, replacing both simultaneously may prevent future problems.

The battery management system in your vehicle will adapt to the new auxiliary battery and optimize charging profiles accordingly. After installation, some vehicles require a brief adaptation period or battery registration procedure using diagnostic tools to ensure proper system operation.

AGM batteries handle frequent charge-discharge cycles far better than conventional flooded batteries, making them ideal for start-stop systems and heavy accessory use. The absorbed electrolyte design prevents spills and allows mounting in various positions, important for auxiliary batteries often located in passenger compartments.

The low internal resistance of AGM construction enables faster charging and better voltage stability under load. ACDelco auxiliary batteries with AGM technology also resist vibration damage and perform reliably across extreme temperature ranges, critical for secondary batteries that may be mounted in less protected locations than primary batteries.

Compatibility depends on your vehicle’s group size specification, terminal configuration, and electrical system requirements. Consult your owner’s manual or the battery label on your current auxiliary battery to identify the correct group size.

Vehicles from European manufacturers like BMW, Mercedes-Benz, and Audi commonly use auxiliary batteries, as do many domestic vehicles with start-stop technology. The ACDelco auxiliary battery meets OE specifications for these applications, but you must verify physical dimensions, terminal type, and electrical specifications match your vehicle’s requirements before purchase.

Under normal operating conditions with a properly functioning charging system, the acdelco auxiliary battery typically provides 4-6 years of reliable service. Actual lifespan varies based on climate, driving patterns, and electrical load demands.

Vehicles that primarily operate in city traffic with frequent start-stop cycles may experience slightly shorter battery life compared to highway-driven vehicles. Extreme temperatures, both hot and cold, accelerate battery aging. Regular inspection of the charging system and avoiding deep discharge conditions help maximize auxiliary battery longevity.

Basic hand tools suffice for most auxiliary battery installations, including wrenches for terminal connections and hold-down hardware. However, some vehicles position the auxiliary battery in locations requiring removal of seats, trim panels, or cargo floor components.

Always disconnect both batteries starting with negative terminals before beginning installation. Many European vehicles require battery registration using diagnostic scan tools after replacement to inform the battery management system of the new battery’s specifications. If you’re uncomfortable with these procedures, professional installation ensures proper integration with your vehicle’s electrical system and prevents potential diagnostic issues.

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