Battery charging rooms are classified into the spaces posing an increased risk of fire. During charging, from all cells and secondary batteries containing aqueous solutions of electrolytes, gases are excreted. This is a result of the electrolysis of water under the influence of the charging current. Hydrogen and oxygen are produced, according to Faraday's law.
In the case of releasing of these gases into the environment (a hall, a magazine) there is the possibility of formation an explosive mixture, if the volume concentration of hydrogen in air exceeds 4%. Hydrogen moves up very quickly and its retention in alcoves, niches resulting from the construction of the roof and the roof is particularly dangerous. That is why the hydrogen detection system is a very important part of equipment for our battery charging rooms.
Parameters related to the evaluation of hydrogen explosion hazards:
- colorless, odorless, lighter than air 14.7 times
- form an explosive mixture with oxygen and air
- LEL 3.4 g / m3 (lower explosion limit)
- UEL 63 g / m3 (upper explosion limit)
Measurements of batteries gassing are difficult, and there are only a few publications on this topic . Number of gases released depends on the size and age of the battery, the degree of contamination and the temperature of the electrolyte. The following hydrogen calculator was prepared on the basis of EN 50273-3 (Safety requirements and installation for secondary batteries. Part 3 - traction batteries.) It is possible to check how much hydrogen forklift batteries or cars generate to the nearest environment.
Example calculations - one 48V battery voltage and capacity of 620Ah of high-storage warehouse truck Reach Track type charging by a rectifier with rated current 120A, can release into the environment over 0.3 m3 of hydrogen per hour.