Choosing the right car battery can be a confusing and expensive endeavor, especially with prices consistently on the rise. Where just a few years ago a quality car battery might cost under $100, today many options exceed $100, with premium models surpassing $200. This increase in cost makes an informed purchasing decision more crucial than ever.
The video above delves deep into comparative testing of several popular car battery brands, putting them through rigorous challenges to determine their true performance. Our aim here is to complement that detailed analysis by providing a comprehensive written guide, expanding on the key insights and data presented.
Decoding Car Battery Performance Metrics
Understanding the terminology associated with car batteries is the first step toward making a smart purchase. Several key metrics dictate a battery’s capability and suitability for your vehicle.
The most commonly cited figures include Cranking Amps (CA), Cold Cranking Amps (CCA), and Internal Resistance (mOhms).
Cranking Amps (CA) vs. Cold Cranking Amps (CCA)
Cranking Amps (CA) measure the amount of current a battery can deliver at 32°F (0°C) for 30 seconds while maintaining at least 7.2 volts. This indicates the battery’s ability to start your engine in moderate temperatures.
Cold Cranking Amps (CCA), however, are often more critical, particularly for drivers in colder climates. CCA measures the current a battery can deliver at 0°F (-18°C) for 30 seconds, also while maintaining at least 7.2 volts. A higher CCA rating means better starting power in freezing conditions, making it a vital consideration for winter performance.
Understanding Internal Resistance
Internal resistance is a measure of a battery’s efficiency in delivering high current on demand. Expressed in milliohms (mOhms), a lower internal resistance indicates a more efficient battery capable of supplying power with less energy loss. For a new car battery, a reading under 5 mOhms is generally considered excellent, signifying strong performance.
Voltage and Charge Status
A car battery’s voltage is a direct indicator of its charge level. A fully charged 12-volt car battery should read above 12.6 volts. At 12.4 volts, the battery is still considered charged but not at full capacity, while anything below 12.4 volts suggests the battery needs to be recharged to prevent damage and ensure reliable starting.
Flooded Lead Acid vs. Absorbed Glass Mat (AGM) Batteries
The market primarily offers two main types of car batteries: flooded lead-acid and Absorbed Glass Mat (AGM). The video tested both types, highlighting their distinct characteristics and performance profiles.
Flooded Lead-Acid Batteries
These are the most common and traditional type of car battery, often more affordable. They contain liquid electrolyte that bathes lead plates, necessitating regular checks and topping off with distilled water in some cases. Flooded lead-acid batteries are reliable workhorses, suitable for a wide range of vehicles and driving conditions.
- **Pros:** Generally less expensive, widely available, proven technology.
- **Cons:** Requires occasional maintenance (for non-sealed versions), less resistant to vibration, susceptible to electrolyte spillage, shorter cycle life compared to AGM.
Absorbed Glass Mat (AGM) Batteries
AGM batteries utilize fiberglass mats to absorb the sulfuric acid electrolyte, making them spill-proof and maintenance-free. They are typically found in vehicles with start-stop technology or those requiring higher electrical loads. The video’s tests included the Optima RedTop and DieHard Advanced Gold, both AGM batteries.
- **Pros:** Maintenance-free, superior vibration resistance, better deep-discharge recovery, faster charging capabilities, lower internal resistance, longer lifespan.
- **Cons:** Significantly more expensive, can be sensitive to overcharging.
The choice between these types often comes down to your vehicle’s requirements, driving habits, and budget. Many newer vehicles are designed specifically for AGM batteries due to their advanced electrical systems.
Real-World Car Battery Test Results: A Deep Dive
The video rigorously tested six batteries: four flooded lead-acid (Walmart EverStart, Duralast Gold, O’Reilly Super Start Premium, Autocraft Silver) and two AGM (Optima RedTop, DieHard Advanced Gold). All batteries were charged to full capacity with a 750-milliamp trickle charger before testing began.
Initial Cranking Amps at 75°F and Internal Resistance
The first set of tests at a comfortable 75°F (24°C) showed varied initial performance. The O’Reilly Super Start led the pack in raw cranking amps, delivering 1,133 CA, closely followed by the Walmart EverStart at 1,115 CA and the Optima at 1,125 CA. The DieHard slightly outperformed the Optima with 1,148 CA and an impressive internal resistance of 2.69 mOhms.
Internal resistance figures were particularly telling. As expected, the AGM batteries showed superior efficiency: the Optima registered 2.76 mOhms, and the DieHard an even lower 2.69 mOhms. Among the flooded lead-acid batteries, the O’Reilly Super Start performed best at 3.42 mOhms, marginally better than the Walmart EverStart’s 3.48 mOhms.
The Challenging 30-Minute Load Test
A demanding 30-minute load test, drawing 42 to 44 amps, pushed all batteries. Remarkably, every battery survived this tough challenge without triggering low voltage alarms. After allowing the batteries to rest overnight, their post-drain performance was assessed.
The Walmart EverStart performed exceptionally well, retaining 12.59 volts and 999 CA, still strong enough to start a car. The O’Reilly Super Start also held up impressively at 12.47 volts and 1,044 CA. Conversely, the Autocraft (12.34V) and Optima (12.26V) dropped below 12.4 volts, indicating a definite need for recharging.
Comparing Charging Speeds
The charging test involved a one-hour charge at 10 amps to observe voltage recovery. As anticipated, the AGM batteries demonstrated faster charging rates. The DieHard showed the most significant voltage increase, rising by 0.52 volts from 12.49V to 13.01V.
The Optima also performed strongly, with a 0.46-volt increase. Among the flooded lead-acid batteries, the Autocraft had the largest increase of 0.38 volts, while the Walmart EverStart, which started at a higher voltage, still ended up at a robust 12.83 volts.
Cold Cranking Amps: Performance at 0°F and -20°F
This critical test involved freezing batteries for 24 hours at 0°F (-18°C) and then at -20°F (-29°C) to measure their cold-weather starting power. At 0°F, the Walmart EverStart (766 CCA) and Duralast (753 CCA) outshone their flooded lead-acid counterparts. The Optima (751 CCA) also performed well, displaying excellent internal resistance at 4.16 mOhms, but surprisingly, the DieHard struggled significantly, delivering only 697 CCA.
The results at -20°F further solidified the performance hierarchy in extreme cold. The Walmart EverStart and Duralast tied for the top spot, both producing 708 CCA. The O’Reilly Super Start followed closely at 683 CCA. Both AGM batteries saw a more substantial drop in performance than expected, with the Optima at 629 CCA and the DieHard at a mere 580 CCA.
Interestingly, when comparing the delivered CCA against their respective ratings, the least expensive Walmart EverStart consistently emerged as a top performer in cold weather, often exceeding or coming closest to its rated CCA.
Manufacturer Insights and Warranty Considerations
A significant takeaway from the testing is the prevalence of certain manufacturers. Johnson Controls, for instance, is a dominant force, producing the EverStart, Duralast Gold, Interstate, Autocraft Silver, and Optima batteries. East Penn Manufacturing makes the O’Reilly Super Start and NAPA batteries, while Enersys produces the DieHard and Odyssey brands.
This ‘re-badging’ means that batteries sold under different brand names can sometimes be identical internally, offering similar performance at different price points. As observed with the EverStart and Duralast, paying more doesn’t always guarantee better performance.
Warranties are also an important factor. The EverStart offered a 5-year warranty with a 3-year free replacement, while the Autocraft provided a 2-year full replacement, and both Optima and DieHard included a 3-year free replacement. Longer warranties offer greater peace of mind and protection for your investment.
Choosing the Optimal Car Battery for Your Needs
Based on the extensive testing, several key recommendations emerge:
- **For Flooded Lead-Acid Vehicles:** If your car is designed for a flooded lead-acid battery, sticking with this type often provides the best value. The Walmart EverStart consistently demonstrated excellent performance across various tests, especially in cold cranking amps, despite being one of the least expensive options. The O’Reilly Super Start also proved to be a strong contender, outperforming some higher-priced alternatives. It’s often wise to choose between the Costco Interstate battery or the Walmart EverStart if their prices are competitive, considering they share the same manufacturer (Johnson Controls) as other pricier brands.
- **For AGM-Equipped Vehicles:** If your vehicle originally came with an AGM battery, it’s generally best to replace it with another AGM. Their benefits in vibration resistance, deep cycling, and maintenance-free operation are crucial for modern vehicles with complex electrical demands. For those in warmer climates where freezing temperatures are not a major concern, the DieHard Advanced Gold showed strong performance. However, if you experience significant cold, the Optima RedTop appears to be a more reliable choice for its better cold-weather CCA retention.
- **The Value Principle:** The testing strongly supports the idea that you don’t always have to pay more to get more. The Walmart EverStart, made by Johnson Controls, offered exceptional performance for its price, proving that careful research can lead to significant savings without compromising quality.
Ultimately, the best car battery for you will depend on your specific vehicle requirements, your local climate, and your budget. Carefully considering the detailed test results and understanding the characteristics of each battery type will empower you to make an informed decision.
Igniting Answers: Your Car Battery Questions
What are the two main types of car batteries discussed in the article?
The article primarily discusses two main types of car batteries: Flooded Lead-Acid batteries and Absorbed Glass Mat (AGM) batteries.
What do ‘Cranking Amps (CA)’ and ‘Cold Cranking Amps (CCA)’ mean for a car battery?
Cranking Amps (CA) measure a battery’s power at 32°F for starting in moderate temperatures. Cold Cranking Amps (CCA) measure its power at 0°F, which is vital for starting in freezing conditions.
How can I tell if my car battery is fully charged?
A fully charged 12-volt car battery should show a reading above 12.6 volts. A reading below 12.4 volts means it needs to be recharged.
Which type of car battery should I choose for my vehicle?
If your car originally came with an AGM battery, it’s generally best to replace it with another AGM. For most other vehicles, a flooded lead-acid battery like the Walmart EverStart can offer excellent performance and value, especially if it meets your car’s requirements and climate.