Sealed, maintenance-free ACUMAX lead-acid batteries with a designed life of 10 - 12 years are made in AGM technology - the electrolyte is trapped in glass fiber separators with high porosity. They use the hydrogen recombination process, which is bound with oxygen to form water molecules. This eliminates the need to replenish the electrolyte and allows them to be used in rooms without special forced ventilation. The batteries are equipped with one-way self-sealing pressure valves that prevent excessive pressure and protect the housing from bursting.