So You Own An AGM Battery...

Tom_M wrote:

MEXICOWANDERER wrote:
AGM batteries can sulfate just like any other lead acid battery. Other than by Ouija Board how would YOU determine if a battery has become sulfated and how severe is the sulfation, and if desulfation (equalization) has been done properly.

Desulfation and equalization are two different processes. You equalize wet cell batteries to distribute the acid equally within a cell. You can not equalize an AGM or gel battery. Here's an excerpt from a Deka battery document:

Acid stratification can occur in conventional wet cells. During charge, acid is released at the plate surfaces. During discharge, acid is consumed at the plate surfaces. Since the concentration is not uniform, diffusion (spontaneous mixing by random molecular motions) begins. If this mixing occurred rapidly, stratification would not occur, but it is relatively slow, allowing lighter parts of electrolyte to “float” toward the surface and heavier parts to “sink” toward the bottom.

The top portion of the plates do not perform as well in contact with lower concentration electrolyte. The bottom portion of the plates do not perform as well with the higher concentration, and will corrode prematurely. High voltage “equalization” charging is sometimes used in wet batteries to make gas bubbles that re-mix the electrolyte.

Because the immobilized gel will not “float” or “sink” within itself when a non-uniform concentration exists, it cannot stratify. Therefore, no high-voltage equalizing charge is necessary. Simply recharge at the standard 13.8 to 14.1 voltage setting. This means longer life and consistent performance in stationary and standby applications.

Electrolyte in an AGM battery is strongly held by the capillary forces between the glass mat fibers, but not completely immobilized. Stratification is possible in extremely tall cells, but cannot occur in batteries of the size covered in this document.