In EN 50272-3 it has been stated, that the necessary ventilation airflow for a battery location or compartment shall be calculated by the following formula:
Q = v * q * s * n * Igas * Cn / 100 [m3/h]
Resolved into = 24 * 0,00042 * 5 * n * Igas * Cn / 100
Final formula
Q = 0,05 * n * Igas * Cn / 100 [m3/h] |
Q = Ventilation air flow [m3/h]
v = Necessary hydrogen dilution factor: 24
q = 0,42 * 10-3 [m3/h] generated hydrogen
s = Safety faktor: 5
n = Number of cells
I gas = Current producing gas during the gassing phase of charge [Amp/100Ah] See Table 1.
C n = Nominal capacitet [Ah]
Table 1
| Charger characteristic |
I gas : vented cells |
I gas : valve regulated cells |
IU:Voltage limit = 2,4 V/c |
2 |
1 |
IUI: No voltage limit |
max 6 |
max 1,5 |
W: Taper charging |
Typical values in the range of 5 to 7 |
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The specified values are for "worst case" conditions
Natural ventilation
In battery rooms, areas and enclosures require an air inlet and outlet, each with a minimum free area of opening calculated by the following formula: Area = 28 * Q [cm2]
For the purpose of this calculation the air velocity is assumed to be >0,1 m/sec
Large and well ventilated rooms shall have a free volume of at least 2,5 * Q [m3]
For the purpose of this calculation the air velocity is assumed to be >0,1 m/sec
The minimum distance between 2 chargers shall be 2 m.
The air extracted from the charging area/room shall be exhausted to the atmosphere outside the building
Removable covers or seats shall be removed prior to charging
Suitable ventilation openings shall be provided in the battery container, compartment or cover so dangerous accumulations of gas do not occur.
Where the airflow Q con not be obtained with natural ventilation, forced ventilation shall be used to secure the required exchange of air for the mode of operation.
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