Sealed AGM Batteries

All of the AGM batteries we sell at Voodoo Solar are of the deep-cycle variety, suitable for battery-based solar installations, as well as marine and RV applications. AGM (absorbed glass mat) is a relatively new battery technology that offers several specific advantages over more traditional designs. As with most things in life, these advantages are balanced by certain less desirable attributes.

AGM batteries are just like flooded lead acid batteries, except the electrolyte is being held in the glass mats, as opposed to freely flooding the plates. Very thin glass fibers are woven into a mat to increase surface area enough to hold sufficient electrolyte on the cells for their lifetime. The fibers that comprise the fine glass fibers in the glass mat do not absorb nor are affected by the acidic electrolyte they reside in. These mats are wrung out 2-5% after being soaked in acids, prior to sealing the battery. The AGM battery can now accumulate more acid than is available, and never spill a drop.

All AGM batteries have enhancements over flooded lead acid batteries:

1. Purer lead in the plates, as each plate no longer needs to support its own weight, due to the sandwich construction with AGM matting. Traditional cells must support their own weight in the bath of acid.

2. Fluid retention - un-spillable.

3. High specific power or power density, holding roughly 1.5x the AH capacity of flooded batteries due to purer lead.

4. Low internal resistance allowing them to be charged and discharged quite rapidly.

5. Water conservation - never requires addition of water.

6. No significant gassing under normal operating conditions, so AGM batteries usually don't require venting.

7. No long term electrolyte stratification, which is desirable when the battery is left unattended and unused over long periods.

However, AGM batteries are often twice as expensive compared to similar flooded battery, and are less tolerant of deep discharges. Charging voltages must be more closely regulated because AGM batteries are permanently damaged by overcharging. Although AGM batteries have a similar lifespan to some of the lower-cost flooded batteries they do not last as long as heavy-duty deep cycle batteries, therefore offering a lower overall value in the long run.

Choose AGM deep cycle batteries when their unique qualities are needed for the specific application.