The company’s AGM (absorbed-glass-mat) Maintenance-Free battery, for example, has thin fiberglass layers between the plates that are saturated with a water/acid mix to about 95% of their capacity. The plates are then compressed and welded or soldered in place. Because the plates and mats are packed fairly tight, they are essentially immune to vibration. This technique also eliminates water loss. And after the battery is permanently sealed, it never needs to be refilled with water or its acid level checked. (The battery is shipped dry with a pack of highgravity acid that is added during installation.)
The AGM batteries also use lead-calcium, which holds its specific gravity three times as long as conventional lead-antimony batteries. This translates into longer periods between charges when the battery is used in standby mode, such as summer or winter storage.