Utilizing pressure-controlled vent valves and sealing with an epoxy compound special to the job.
To stop electrolyte acid from leaking or evaporating, it is absorbed in specific glass mat separators.
Can be used in any posture; no leaking. However, installing upside-down is not advised.
Using a recombination reaction to turn hydrogen and oxygen into water and stop them from leaving can keep the quantity of acid water constant.Without maintenance. Like a flooded battery, there is no need to add water.