MICROCAT^® CATALYSTS

One of the most immediate, observable effects of installing a catalyst in a VRLA cell is a sudden drop in the float current. Typically, float currents are one half or less when a catalyst is installed. In a VRLA cell, the negative plate does double duty compared with a flooded cell. In addition to normal negative plate functions, it is also where oxygen and hydrogen are recombined into water, making the cell maintenance free.

When this process is too efficient, excess oxygen reaching the negative plate causes it to become depolarized. When the negative plate is depolarized, the charging system will supply more current in an effort to bring the cell voltage up. The additional current becomes excessive overcharge on the positive plate, which has many damaging effects on the cell.

Adding a Microcat catalyst to the cell prevents some of the oxygen from reaching the negative plate and allows the negative plate to stay polarized. This means that less current needs to be supplied to the cell from the charging system, manifesting itself as lower float current.

VRLA cells have many potential failure modes. A number of these failure modes can be mitigated by the catalyst technology – failure modes such as cell dry-out; positive plate, grid and strap corrosion; thermal runaway; and capacity loss due to negative plate depolarization.

Employment of a Microcat catalyst will lessen the occurrence and impact of these failure modes, thereby increasing the working life of the cell and the battery.

Hydrogen and oxygen gases are recombined into water by the Microcat catalyst inside the cell rather than exiting the cell.

Too much of these gases leaving the cell can lead to premature dry-out and cell failure. Cell dry-out has been the predominant cause of customer dissatisfaction with VRLA technology.

Many VRLA cells in service are failing capacity tests because their negative plates are depolarized.

In fact significant capacity increases have been seen on some cells just by installing a catalyst.

A reduction in float current reduces the amount of overcharge on the positive plate, which directly impacts the corrosion rate. The design life of a lead acid cell is based upon the corrosion of the plate, barring any other unforeseen failure modes.

Any excess current above that needed to charge the cell is converted directly into heat. A reduction in float current means less heat produced. This can result in a cooler environment for batteries and electronics and a reduced load on HVAC systems.

Since heating is reduced and float current minimized, there is less risk of thermal runaway.

Reduced float current directly translates into less power purchased.