How does a gel cell work?
A gel cell is a "recombinant" battery. This means that the oxygen that is normally produced on the positive plate in all lead-acid battery recombines with the hydrogen given off by the negative plate. The "recombination" of hydrogen and oxygen produces water (H2O), which replaces the moisture in the battery. Therefore, the battery is maintenance-free, as it never needs watering.
The oxygen is trapped in the cell by special pressurized sealing vents. It travels to the negative plate through tiny fissures or cracks in the gelled electrolyte.
The sealing vent is critical to the performance of the gel cell. The cell must maintain a positive internal pressure. Otherwise the recombination of the gasses will not take place, and the cell will dry out and not perform.
In addition, the valve must safely release any excess pressure that may be produced during overcharging. Otherwise, the cell would be irreparably damaged.
It's important to note that gel cell must never be opened. If opened, the cell loses its pressure, and the outside air will "poison" the plates and cause an imbalance that destroys the recombination chemistry.
How do gel cells recharge? Are there any special precautions?
While our gel cell will accept a charge extremely well due to its low internal resistance, any battery will be damaged by continual under- or overcharging. Capacity is reduced and life is shortened.
Overcharging is especially harmful to gel cells because of their sealed design. Overcharging dries out the electrolyte by driving the oxygen and hydrogen out of the battery through the safety valves. Performance and life are reduced.
If a battery is continually undercharged, a power-robbing layer of sulfate will build up on the positive plate, which acts a s a barrier to electron flow. Premature plate shedding can also occur. Performance is reduced and life is shortened.
Therefore, it is critical that a charge be used that limits voltage to no more than 14.1 volts and no less than 13.8 volts at 68° F. Batteries used in float service should be charged at 13.8 volts. For deep cycle service, a maximum voltage of 14.1 volts should be used. Most of the charge controllers that we offer are compatible with gel cell type of batteries.
Can gel cells be installed in sealed battery boxes?
NO! Never install any type of battery in a completely sealed container. Although the normal gasses (oxygen and hydrogen) produced in a gel cell battery will be recombined as described above, and not escape, oxygen and hydrogen will escape from the battery in overcharge condition (as is typical of any type of battery).
For safety's sake, these potentially explosive gasses must be allowed to vent to the atmosphere and must never be trapped in a hermetically sealed battery box or tightly enclosed space!