Over accu's - AGM EN

In 1972 researchers of the American Gates Rubber Company developed a safe recombinant battery for the US Air Force, with the emphasis on power-to-weight ratio. This was accomplished by positive and negative plates of a calcium alloy, separated by microporous glass fiber mats, in which the electrolyte is absorbed by capillary action. The technique is called, therefore, Absorbed Glass Matt or AGM.

Microporous glass mat separators consist of thin, hollow tubes of unequal length. These fiber mats are only for about 95% saturated with electrolyte, the rest is used for the oxygen migration to the negative plate. This technique is called Starved Electrolyte. To compensate for the small quantity of absorbed electrolyte a Specific Gravity (SG) of 1.30 is used. The principle of starved electrolyte has also a positive effect on the cycle life of the AGM battery. When deeply discharged, the small quantity of electrolyte will be exhausted before permanent damage is done.

Deep discharge?

Just as with Gel batteries, many believe any AGM battery to be a deep cycle battery, suitable for deep discharge applications. That's not necessarily the case. Just as with flooded batteries, the deep cycle performance of a battery is determined by the construction of the plates, not in any way by the electrolyte. AGM batteries are very popular for use in stationary applications such as emergency power supply, telecommunications etc. By using thicker plates very good cyclic performance can be are achieved, quite similar to that of a cyclic gel battery. Unfortunately, that does not detract from the fact that many AGM batteries in particular in recreational applications are, in fact, stationary batteries. These batteries will perform at best around 300 cycles, whereas a proper AGM DC battery will do 500-600 cycles, depending on depth of discharge.