Battery Room Hydrogen Ventilation Calculator
Estimate a battery-room dilution airflow from documented gassing current. This calculation does not classify a zone, design air distribution or approve electrical equipment.
Screening only. This tool does not classify hazardous areas or approve a product, installation or safety system. Use the applicable project requirements, manufacturer data and exact certificate conditions.
Method & limits
Q = 0.05 × n × Igas × Crt × 10^-3 in m³/h. Air changes per hour = Q / room volume. Reference Igas = charge current × gas-emission factor × faulty-cell/aging factor. The cited table gives vented lead-acid (Sb <3%) 5/20 mA/Ah and VRLA 1/8 mA/Ah for float/boost at the stated charging conditions. These are not universal presets for all batteries. The fixed 0.05 method uses the reference gas-volume basis; the source identifies a 1.095 gas-volume correction at 25°C. Air path, fan reliability, charger interlocks, local hydrogen pockets, safety distance and other heat or ventilation loads need separate design.
Frequently asked questions
Are G1-G3 examples standard battery presets?
No. They are arithmetic examples using manually entered Igas values. Actual gassing current must come from applicable battery and charging data.
Why are the presets higher than the gas-emission factor?
Igas includes charge current and the faulty-cell/aging factor, not just the fraction of current producing gas.
Does this apply to lithium-ion batteries?
No. The listed presets and referenced hydrogen-gassing method are for stationary lead-acid batteries, not lithium-ion thermal-runaway ventilation.
Does the air-change value set a room design minimum?
No. It is simply the computed dilution flow divided by room volume. Other rules, air distribution and failure conditions can require more airflow.
Can this determine a hydrogen zone or a suitable light?
No. Area classification and equipment selection are separate. A room-average dilution calculation does not remove local hydrogen hazards.
Sources & verification
Source and calculation review: 2026-11-05. Reference methods do not replace the edition adopted for your project.