Gel Batteries 101

Written by Randy Anderson - Technical Sales & Training Manager

Gel batteries originated in Europe and were first mass-produced by Sonnenschein in Germany for deep cycle and traction applications. They continue to be used almost exclusively today in deep cycle applications that require low power draw over extended periods of time.  Typical flat plate Gel batteries consist of a series of positive and negative plates grouped together in a cell surrounded by a thixotropic gel with a consistency similar to Jell-O. The gel consists of mainly electrolyte that is approximately 30% sulfuric acid by volume.  Like all lead acid batteries, the sulfuric acid in the gelled electrolyte is absorbed into the paste of the positive plate as the discharge process occurs and lead sulfate is formed, this process is reversed when voltage and amperage are introduced into the battery during recharge.

The characteristic of Gel batteries is that they are typically very good in deep cycle applications where longevity is required. However, in most cases they do not produce as much amp hour or reserve capacity to that of similar size AGM or flooded batteries because the sulfuric acid in the gel is slower to release and does not come into contact with as much plate surface area.  For this same reason it is rare to find a Gel battery in a high amp draw application such a car starting battery or a UPS battery application where high bursts of power are required for short periods of time.  You may think that a Gel battery is what you need for your sealed maintenance-free application, but often times an AGM battery may be a more appropriate choice. Always important to do your research and ask questions.

Gel batteries are not widely available in the North American market today and are very limited in the number of footprints and sizes often required by today’s electric vehicles.  Where Gel batteries are used, care must be taken when choosing a proper charger. Gel Batteries are very sensitive to overcharging and chargers must have specific settings for Gel batteries to avoid over voltage, which can cause the batteries to over-gas and dry out.

When choosing a sealed battery for a deep cycle application be sure to take into consideration the capacity requirements, cycle life and recharge parameters before making a purchasing decision.

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