1. GENERAL INFORMATION
Batteries are used to store electrical energy. Many of the things we use every day rely on the instant power provided by batteries. However, the larger batteries found in workplaces can be dangerous and may explode if used incorrectly.
Injuries from batteries include serious chemical burns to the face, eyes and hands, and wounds from flying pieces of metal and plastic. Burns from metal objects that have become very hot or have exploded after short-circuiting the battery’s terminals occur frequently. A particular concern is the overheating of batteries when in use or being charged resulting in fires on STFC sites. Electricity is a major cause of STFC fires. Serious electric shocks, arc flash and burns are common in accidents involving batteries.
There are two main classes of battery: those that can be recharged and those that cannot. This appendix gives advice on how to reduce the risks of using rechargeable batteries.
The two most important types of rechargeable battery are lead/acid and alkaline. Lead/acid batteries are the most common large-capacity rechargeable batteries. There is one in almost every vehicle including cars, motorcycles and fork-lift trucks. They are extensively used in large Uninterruptible Power Supplies (UPS) systems that support computer/communication and machinery control systems.
Alkaline rechargeable batteries, such as nickel-cadmium, nickel-metal hydride and lithium-ion, are widely used in small items such as laptop computers and portable electrical equipment from phones to drills. Large-capacity versions of these cells are now used in transport including EV Cars, scooters, bicycles and UPS applications.
2. TRANSPORT AND STORAGE
Packing and transportation of rechargeable batteries is covered in national and international regulations. The following international regulations for transport, safe packing and carriage of dangerous goods apply:
- Road: European Agreement for the International Carriage of Dangerous Goods by Road (ADR);
- Rail (international): International Convention concerning the carriage of Goods by Rail (CIM) Annex A: International regulations concerning the carriage of dangerous goods by rail (RID);
- Sea: International Maritime Organisation, Dangerous Goods Code; IMDG Code 8 Class 8 corrosives;
- Air: International Air Transport Association (IATA); Dangerous Goods Regulations (latest edition).
For the transportation of lithium cells or batteries refer also to EN 62281 “Safety of primary and secondary lithium cells and batteries during transport”.
For storage of cells or batteries under various climatic conditions, the characteristics regarding charge retention and corrosion effects shall be observed. The primary source of guidance should be the manufacturer’s recommendations which should be followed.
3. CHARGING FOR SERVICE
There are two different types of lead/acid and alkaline rechargeable batteries: valve-regulated (‘maintenance-free’) and vented. In valve-regulated batteries, any hydrogen and oxygen produced during charging does not escape but is converted back into water. You cannot add water to these batteries, as they do not need topping up. In contrast, vented batteries allow any hydrogen and oxygen produced to escape into the surrounding atmosphere. They require regular topping up with water.
A source of ignition – for example, a flame, a spark, a cigarette or any smouldering material, electrical equipment, a mobile phone etc. – will often cause mixtures of these gases to ignite and explode. The explosion is often so violent that it shatters the battery and produces a highly dangerous shower of fragments and corrosive chemicals. Refer to SC20 Controlling Explosive and flammable gases and dusts.
Hydrogen and oxygen are produced more quickly as a vented battery gets close to being fully charged. If you continue charging after the battery is fully charged, a lot of gas will be produced, greatly increasing the risk from explosion.
During charging, gas bubbles often become trapped inside the battery. The mixture of two-parts hydrogen to one-part oxygen produced is perfect for an explosion. When a vented battery is moved, the trapped gases are released into the air around the battery. A tiny spark is all that is needed to ignite the gases. If this happens in a confined space (e.g. inside the battery, or in an enclosure or a poorly ventilated battery room), a violent explosion is likely.
The gases that come out of a vented lead/acid battery during charging often contain a fine mist of sulphuric acid. Take care to avoid breathing these fumes and wear suitable eye protection.
Valve-regulated (‘maintenance-free’) batteries are much less likely to release hydrogen than vented batteries. However, it is still important to take care when charging them. Gas pressure may build up inside the battery if it is charged too quickly or for too long. If this happens, the pressure relief valves in the battery may open and let the hydrogen and oxygen escape. An explosion is likely if this happens close to an ignition source.
To minimise risk during charging of rechargeable batteries, manufacturer’s specified charging procedures and charging regimes shall be applied. For achieving long service life of rechargeable batteries, the manufacturers limit values and operating conditions shall be observed.
Rechargeable batteries should not be left on charge unsupervised for extended periods or overnight unless essential equipment. Where there is a significant number of batteries and charging units consider the use of battery charging/storage cabinets that can contain a fire and are fitted with fire detection. See SC32 Fire Risk Management for further details.
4. INSTALLATION & MAINTENANCE
Rechargeable batteries and UPS systems should be kept in a good state of charge, inspected and maintained in strict accordance with manufacturers' instructions. Where regular impedance or capacitive testing is not undertaken, manufacturer’s life expectancies shall be observed.
Before installing any battery consider orientation, environment and ventilation, other factors include protected from dust, dirt and accidental shorting of their terminals by metallic objects. If charging facilities are installed as part of the equipment, see STFC SHE Code 20: Controlling explosive and flammable gases and dusts.
All battery charging installations must be suitably located following relevant guidance and fire safety advice. See SC32 Fire Risk Management. The tops and sides of all batteries should be kept clean and dry and examined for leaks; any vent holes should be kept clear.
Some equipment is capable of carrying out ‘fully controlled charging’. Here, the charging current is automatically reduced as the battery gets near to being fully charged. This type of equipment greatly reduces the risk of overcharging and so makes charging much safer. It is also important to consider charging parameters when replacing batteries including replacing wet cells for gel batteries of a similar rating.
Care should be taken with all batteries to avoid accidental shorting of their terminals. Insulated tools should be used when working around battery terminals and metal jewellery and watches should be removed. They should not be subjected to mechanical shock or to extremes of temperature. Many explosions happen when batteries are being connected or disconnected. The sparks produced when this is done incorrectly may cause the battery to explode, especially if it has just been charged.
When a battery is isolated from its load or any other battery, its bolted connections should be examined for corrosion and tightness. If connections are corroded, they should be dismantled, cleaned and greased with petroleum jelly, re-assembled and tightened. Do not use acid neutralising agents and take care when tightening bolted connections to avoid damaging battery terminal pillars.
If a battery has a vent plug, ensure it is removed and vent the cell before checking the firmness of the terminal pillars.
Batteries that have distorted or are otherwise damaged should be replaced immediately. Do not attempt to dismantle any battery and do not leave exhausted batteries in equipment.
4.1. Provision against electrolyte hazards
Most of the electrolytes used in batteries are hazardous chemicals and can create irritation or burns to eyes and skin. Inhalation and swallowing of electrolyte is dangerous. In case of direct contact with electrolyte to eyes and skin or inhalation, medical attention is always required.
Properties of electrolyte for topping-up shall comply with IEC 60993 for Ni/Cd. For electrolyte density refer to the manufacturer’s specification.
The preparation of electrolyte solutions for batteries on site should be avoided, where it cannot be avoided, contact SHE Group.
4.2. Spillage and waste disposal
Batteries must never be disposed in general waste, contact a Waste Disposal Officer for advice on battery disposal or employ dedicated battery disposal containers for small dry batteries.
Where electrolyte is spilled:
- Sulphuric acid spillages should be cleaned up with materials such as soda ash (sodium hydrogen carbonate) or sodium carbonate (washing soda).
- Potassium hydroxide spillages should be diluted with copious amounts of water before mopping up.
Surplus electrolyte must be disposed of as hazardous waste, contact a Waste Disposal Officer and consult Safety Code 31 Controlled and hazardous waste disposal and Safety Code 41 Controlling pollution to air, land and water.
For further guidance on disposal of lithium batteries, see Safety Code 27 Receipt and dispatch of hazardous substances or contact the STFC Environmental Officer or local Waste Disposal Officer for advice.
If the spill involves a lithium metal battery, the area should be evacuated and immediately contact the on-site emergency response, who will consult with the STFC Environmental Officer, and a Fire Safety Advisor as required. If battery contents get on the skin, the area should be flushed with clean water for at least 15 minutes and contact first aider for advice.
5. VEHICLE BATTERIES
Electrically powered vehicles being equipment that transports people or goods, including, but not limited to cars, vans, trucks, MEWPs, bicycles, forklift trucks.
Electrically powered vehicles must only be charged in accordance with the manufacturer's instructions or recommendations and at a designated or approved charging point on STFC premises. Charging of electrically powered vehicles in offices or escape routes is strictly forbidden. When charging vehicles only a manufacturer’s approved charger lead can be used.
Any requirements to install new charging points/facilities for electrically powered vehicles must be made in consultation with Estates and must conform to the current IET Code of Practice for electric vehicle charging equipment installations. The fire safety advisor and building fire manager must be consulted prior to installing any new charging points/facilities with regards to RC59 - Recommendations for Fire Safety when charging electrical vehicles. Electrical vehicle charging and parking should be located at least 10m from combustible walls and 7.5m from unprotected openings/extensive glazing in non-combustible walls.
Any new installations must also consider the fire strategy and fire risk assessment for the building/area and these documents must be reviewed in consultation with the Fire Safety team before any risk presented by charging electric vehicles is introduced.
When charging electrically powered bicycles only a manufacturer approved charger and charger lead shall be used.
Prior to first use, all new and used electrical chargers must be tested and inspected in accordance with SC17, during annual test programme or by a department test operative.
6. UPS
A UPS is an electrical apparatus that provides emergency power to a load when the input power source or mains power fails. It is typically used to protect hardware such as computers, data centres, telecommunication equipment or other electrically powered equipment, where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss. UPS normally contain batteries and vary in size from units that are designed to protect a single computer without a monitor, to large units powering entire data centres or buildings. Battery systems can often reach voltage >330vdc and may be as high as 770vdc.
UPS must only be procured from reputable suppliers and must comply with European (CE) Standard and be provided with operating and maintain instruction.
All UPS systems shall be maintained to manufacturer’s instructions and where larger battery systems are installed; condition monitoring of batteries should be carried out annually.
There should be a record of all UPS installed on SFTC sites that is accessible to any electrical person approved to work on or test the electrical installation. The information retained should include type, rating, location and person responsible.
7. REFERENCES
- Using Electric Storage Batteries Safely, general information sheet INDG231 (rev1).
- BS EN 50272-1:2010 Safety requirements for secondary batteries and battery installations.
- BS EN 60079-17:2007 Explosive Atmospheres Electrical
- Personal Protective Equipment at Work Regulations 1992, leaflet INDG174.
- BS EN 374, 420 - Industrial Gloves.
- INDG139 Using electric storage batteries safely.
- IEC60993 Electrolyte for nickel-cadmium cells.
