**Compliments of: Industrial Battery and Charger, Inc.
Charlotte, North Carolina**

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 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 = 10 Batteries

Type = 18-85-21

Ampere Hour = Ampere Hour per Positive x Number of Positive Plates

Ampere Hour = 85 Ampere Hour Plate x 10 Positive Plates

Ampere Hour = 850 Ampere Hour

__Battery Hydrogen Calculation__

850 AH x 0.05 x 18 Cells x 0.016 Cubic Feet / Ampere Hour / Cell =

12.24 Cubic Feet / Hour / Battery x 10 Batteries =122.40 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) ÷ 122.40 Cubic Feet / Hour =

2.2 Hours or 132 Minutes

__Rate of Air Volume Removal__

18,000 Cubic Feet ÷ 132 Minutes =

136.40 Cubic Feet / Minute