Battery Room Max Charge Current from Available Airflow
The inverse of the battery-hydrogen-vent tile: the highest maximum charge current a room's exhaust can safely support, I_max = available_cfm / (0.054 x N) (IEEE 1635), where N is the number of individual 2 V CELLS, not jars. An exhaust of 100 cfm over a 24-cell string supports 77 A; counted as 144 cells (twenty-four 12 V jars) it is only 12.9 A, so mistaking jars for cells overstates the safe current six-fold. Answers 'how much charge current can my fan handle' instead of sizing the fan. A design aid; the applicable code and room design govern.
Formula and source
I_max = available_cfm / (0.054 x N) (N = individual 2 V cells); the inverse of Q = 0.054 x I x N.
The IEEE 1635 / IEEE-ASHRAE Guide 21 battery-room hydrogen ventilation relation solved for the maximum charge current a given exhaust rate can support, holding the room-average hydrogen below 1% (NFPA 855 4% LEL), by name; the applicable code and the room design govern.
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