When comparing pure lead batteries and Absorbent Glass Mat (AGM) batteries, several key differences emerge in terms of their construction, performance, and application suitability. Both types of batteries have their own strengths and weaknesses, making the choice between them dependent on specific usage requirements.

In terms of construction, pure lead batteries typically feature a traditional lead-acid design with a liquid electrolyte. The plates are submerged in the electrolyte, which allows for a relatively straightforward chemical reaction during charging and discharging. On the other hand, AGM batteries use a fiberglass mat saturated with electrolyte, which immobilizes the liquid. This design makes AGM batteries spill-proof and more resistant to vibration, making them suitable for applications where movement and orientation changes are common, such as in vehicles.

Performance-wise, pure lead batteries often offer a higher capacity and better deep-discharge capabilities. They can be discharged to a lower state of charge without significant damage, making them ideal for applications that require sustained power over long periods, such as off-grid energy storage. AGM batteries, while having a lower deep-discharge tolerance, excel in high-rate discharge scenarios. They can deliver a large amount of current in a short time, making them well-suited for starting applications, like in cars and boats, where a sudden burst of power is needed to start the engine.

The lifespan of these batteries also varies. Pure lead batteries, especially those with high-quality construction, can have a relatively long lifespan when properly maintained. Their ability to withstand numerous charge-discharge cycles contributes to their longevity. AGM batteries, due to their sealed construction and reduced water loss, also have a long lifespan, often outlasting traditional flooded lead-acid batteries. However, they may be more expensive upfront compared to pure lead batteries.

In terms of maintenance, AGM batteries have an advantage as they are virtually maintenance-free. The sealed design prevents electrolyte evaporation and spillage, eliminating the need for regular topping up of water. Pure lead batteries, on the other hand, require more maintenance, including periodic checks of the electrolyte level and addition of distilled water when necessary.

Overall, the choice between pure lead batteries and AGM batteries depends on the specific application. For applications requiring high capacity and deep-discharge capabilities, pure lead batteries may be the better option. For scenarios where vibration resistance, high-rate discharge, and low maintenance are crucial, AGM batteries would be more suitable.