VRLA Battery Maintenance and Safety UTC Region 3 Meeting October 4, 2012 Battery Lifespan The IEEE defines “end of useful life” for a UPS battery as being the point when it can no longer supply 80 percent of its rated capacity in ampere-hours. When the battery reaches 80 percent of its rated capacity, the aging process accelerates and the battery should be replaced. Expected life can vary greatly due to environmental conditions, number and depth of discharge cycles, and adequate maintenance. The risks of improperly maintained batteries are loss of capacity, fire, property damage, and personal injury. Factors that determine a battery’s life span are Ambient Temperature Battery Chemistry Positive Plate Design and Thickness Cycling Preventive Maintenance Why do batteries fail? Batteries can fail for a multitude of reasons, but common reasons are: High or uneven temperatures Inaccurate float charge voltage Loose inter-cell links or connections Loss of electrolyte due to drying out or damaged case Lack of maintenance, aging How do batteries fail? Plate separation - Repeated cycling (charging and discharging), damage during handling and shipping and overcharging Grid corrosion - Normal aging, operating in an acidic environment and high temperatures Internal short circuit - Heat (plates expand causing shorts), separator failure, handling and shipping, and grid corrosion External short circuit - Human error (shorting terminals) and leaks Sulfation of plates - Sitting discharged for an extended period, not on charge or being undercharged Excessive gassing - Often due to high temperatures or overcharging Drying out - Excessive gassing, high temperatures or overcharging What is thermal runaway? Thermal runaway occurs when the heat generated in a lead-acid cell exceeds its ability to dissipate that heat, which can lead to an explosion, especially in sealed cells. The heat generated in the cell may occur without any warning signs and may be caused by: Overcharging Excessive charging Internal physical damage Internal short circuit Hot environment. Battery temperature should be measured during PM checks. Handling Batteries A physical inspection of batteries should be made before handling: Swelling Leaking Visible Damage Metal watches or jewelry should not be worn while handling batteries. Wear safety goggles or other eye protection. Use of rubber gloves and apron is recommended. All tools should be adequately insulated to minimize the possibility of shorting. Keep sparks, flames, and smoking materials away from the battery area and explosive gases. In the event of contact with electrolyte, flush immediately and thoroughly with water. MSDS Sheets Storing Batteries Due to the self-discharge characteristics of lead-acid batteries, it is imperative that they be charged periodically during storage. To prolong shelf life without charging, store batteries at 10°C (50°F) or less. Store batteries in cool, dry, well-ventilated areas with impervious surfaces and adequate containment in the event of spills. Keep away from fire, sparks and heat. Avoid stacking too high Avoid excessive shock, impact, or dropping batteries Spills or Leaks Material safety data sheets (MSDS) should be available on site for reference if needed. You should always refer to the MSDS for specific precautionary measures. Stop the flow of materials, contain/absorb small spills with dry sand, earth, or vermiculite. Do not use combustible materials. If possible, carefully neutralize spilled electrolyte with soda ash, sodium bicarbonate or lime. Wear acid-resistant clothing, boots, gloves, and face shield. Do not allow discharge of un-neutralized acid to sewer. Spill containment systems may or may not be required for VRLA batteries. (Review local requirements that may apply) Transporting Batteries VRLA batteries marked as “non-spillable” are safe and approved for all transportation methods by DOT for transportation by truck, rail, ocean and air transportation because they meet the requirements of 49 CFR 173.159 (d). Per 49 CFR 173.159(e) When transported by highway or rail, electric storage batteries containing electrolyte or corrosive battery fluid are not subject to any other requirements of this subchapter, if all of the following are met: (1) No other hazardous materials may be transported in the same vehicle; (2) The batteries must be loaded or braced so as to prevent damage and short circuits in transit; (3) Any other material loaded in the same vehicle must be blocked, braced, or otherwise secured to prevent contact with or damage to the batteries; and (4) The transport vehicle may not carry material shipped by any person other than the shipper of the batteries. Disposal of Batteries Batteries that are replaced can still contain a significant amount of hazardous waste, including the electrolyte and lead. You must comply with EPA guidelines for the disposal of all batteries. Many states require lead-acid batteries be recycled Large generators have more stringent requirements for battery disposal guidelines and documentation. Only approved recyclers should be used to avoid problems with environmental concerns. Conclusions Benefits of preventive maintenance are: Increased lifespan Greater reliability Reduced possibility of failure Handling of batteries require reasonable precaution Transportation of batteries is safe if properly prepared. Proper recycling or disposal of batteries is required.