Are AGM Batteries Compatible in an Older Car and What Issues Might You Encounter?

When considering a switch to AGM (Absorbent Glass Mat) batteries for an older car originally equipped with standard flooded cell batteries, there are several questions that often arise. This article aims to address these concerns and provide insights into the compatibility and potential issues associated with using AGM batteries in an older vehicle.

Compatibility of AGM Batteries in Older Cars

The first question is whether AGM batteries are compatible with older cars that originally came equipped with standard flooded cell batteries. The answer is a resounding yes.

Q1: Are AGM batteries compatible in an older car that came with a standard flooded cell battery?

A1: Yes, I have used them for decades without issue.

Potential Issues with AGM Batteries

While AGM batteries are generally compatible, there are a few issues that might arise when using them in an older car. These issues are typically minor but can affect the performance and longevity of the battery.

Q2: What issues might I experience?

A2: No real issues but an anomaly. The primary issue is that charging an AGM battery to full capacity might require a higher voltage than typically provided by an older car's alternator, which usually outputs around 14 VDC instead of the 15 VDC recommended for AGM batteries.

Charging and Voltage Considerations

To ensure a full charge, AGM batteries may require a charging voltage of 14.4 Volts. The standard car alternator, however, generally outputs around 13.8 VDC.

While this discrepancy might seem significant, it is not usually a cause for concern. The AGM battery still charges adequately for most applications, especially given the higher capacity typically sought in AGM batteries. Many people find that these batteries are more reliable in sub-freezing temperatures and have a longer lifespan.

Backup and Reliability

One common practice is to carry a backup AGM battery. This can be especially useful if your car's primary battery goes dead, as the backup battery can serve as a jump starter. However, it is important to charge this backup battery with a smart charger to prevent damage from incorrect charging methods.

Advantages of AGM Batteries

Despite the potential issues, AGM batteries offer several advantages that make them a worthwhile choice for many car owners.

Advantages of AGM Batteries

Superior Power: AGM batteries provide superior power to support the higher electrical demands of modern vehicles and start-stop applications.

Reduced Vibration: These batteries are highly resistant to vibration, making them ideal for vehicles that spend a lot of time on bumpy roads.

Sealed and Maintenance-Free: AGM batteries are totally sealed and non-spillable, requiring no maintenance.

Longer Lifespan: Due to their design, AGM batteries generally last longer than standard flooded lead acid batteries.

Charging Requirements

While AGM batteries can be used in any car regardless of age, it is important to note that they require a specific smart charger to charge them properly. Most car alternators are not equipped to provide the correct charging voltage and current, which can reduce the battery's lifespan over time.

However, some modern cars are equipped with smart charging systems. Without a regulated circuit to manage the charging current, an AGM battery may not receive the optimal charge, leading to a shorter lifespan. This is a significant consideration, especially for those who value the longevity and reliability of their batteries.

Conclusion

AGM batteries are a viable and often advantageous choice for older cars, provided that the charging system is appropriately managed. While there are minor issues to consider, the benefits of using AGM batteries, such as reliability in cold temperatures and a longer lifespan, make them a worthy upgrade for many vehicle owners.