__Hydrogen Concentration Worksheet__

During the recharging process, a lead battery releases hydrogen and oxygen through the electrolysis

of sulfuric acid. The beginning of gassing is determined by the battery voltage, but the amount of gas

depends on the current that isn't absorbed by the battery and is used in the electrolysis. As the battery

reaches its full state of charge, the acceptance of current becomes less and the liberation of hydrogen

is more.

**Four percent (4%) concentration of hydrogen is dangerous and has a potential for an explosion.**

Generally, the maximum allowable concentration of hydrogen is 1.50% of the room's cubic footage. To

keep the hydrogen concentration below 4%, adequate ventilation or proper air exchange of the room

must be provided.

__ ____Rate of Hydrogen Release__1 Ampere x 1 Hour x 1 Cell = 0.016 cubic feet / Ampere Hour / Cell

**Battery Hydrogen Calculation**

Ampere Hour x Finish Rate (percent) x Number of Cells x 0.016 Cubic Feet / Ampere Hour / Cell

__Example:__

Quantity = 20 Batteries

Type = 3DJ-200

Ampere Hour = 200 Ampere Hour

Battery Hydrogen Calculation

200 AH x 0.05 x 60 Cells x 0.016 Cubic Feet / Ampere Hour / Cell =

9.6 Cubic Feet / Hour / Battery x 20 Batteries = 192.0 Cubic Feet / Hour

__Room Calculation__

40' Long x 30' Wide x 15' High = 18,000 Cubic Feet

18,000 Cubic Feet x 0.015 (Maximum Allowable Concentration) = 270 Cubic Feet (Maximum)

Rate of Concentration Calculation

270 Cubic Feet (Maximum Allowable) ÷ 192.0 Cubic Feet / Hour = 1.4 Hours or 85 Minutes

Rate of Air Volume Removal

18,000 Cubic Feet ÷ 85 Minutes = 211.76 Cubic Feet / Minute

You will need at least one exchange of air per hour in the substation with the existing air conditioning system in order to NOT have a ventilation fan to exhaust battery gasses.