How to use mobile batteries safely

Operate a temporary electrical installation safely

Safe handling of an electrical installation largely comes down to strictly following the instructions and working in accordance with industry standards and safety regulations. Since mobile batteries are a relatively new product in the temporary energy market, the necessary legislation and regulations are lacking. That is why 24/7 remote monitoring the functioning of the system is a good starting point for safely handling a temporary electrical installation. This way you can identify any problems early and act upon them. With our software you can always see how the battery is functioning and the software itself ensures that we stay within the operational and technical limits of the battery.

Mobile batteries are often plug-and-play. This means that a system is ready to plug in and that the control elements of the electrical installation are located on the outside of the system. This contributes to safe operation and use of the system. To exclude the risk of electrocution, the system switches off immediately when a container door is opened. In addition to the control panel, there is also a physical emergency stop. In practice, this will almost never be used, because the system monitoring in the battery itself switches off in a safe way in a deviating situation. In this case, the system also sends a warning to both the installation manager and our control room.

Standards and Safety Regulations

Laws and standards determine how safe it is to work on electrical installations and how electrical installations are used. For example, there are established standards and rules for the safe construction, expansion and adaptation of safe low-voltage installations and for the safe operation of activities near, on or with electrical objects in the low-voltage area. In addition, there are procedural provisions that describe that only authorized persons have access to the electrical installation, a project manager has been appointed, cables are safely laid and covered if necessary, and installations are protected by fences.

The PGS-37 standard

At the time of writing, the PGS-37, a standard for the safe use of lithium batteries, is still under development. We welcome the introduction of this guideline because it can give us concrete guidelines when we discuss safety aspects with our clients at the start of projects. At the same time, the safe execution of projects requires more than just a guideline. All parties involved should sit down to discuss and define the various responsibilities in the field of safety from a practical point of view.

Installing a battery safely

Mobile batteries are often used for a shorter period of time to temporarily provide a specific location with power. This makes it even more important to have clear instructions for the safe installation of a battery, whether at a public event such as the Green Caravan at the Vuelta or at a zero-emission construction site. At Greener, we use at least the following instructions for safe battery installation:

• Place the container on a flat surface and use ramps if the surface is not paved.
• Make sure that the container is set up in such a way that it cannot be hit or pierced by passing vehicles.
• When installing the battery, keep a distance from solid objects of 5 (minimum) to 10 (target) meters.
• Allow at least 1 meter of free space on all sides of the battery.
• Make sure that the battery is accessible for a truck due to service and maintenance, and to provide emergency access in an emergency.
• Do not install the battery along escape routes.
• Do not place the battery near unauthorized persons or the public.

Cooling systems

To ensure that battery systems work properly and safely, they are almost always equipped with active cooling in the form of air conditioning. Keeping the system at temperature ensures better performance, longer battery life and safe deployment. If extreme conditions unexpectedly cause a high temperature rise, the cooling system sends an initial alarm signal to the user at a cell temperature of 30°C. If the temperature rises further to 65 °C, the system switches off as a precaution and the user receives another message. To put these temperatures in perspective, the dreaded thermal runaway (see the next section Fire safety) only occurs at temperatures above 130°C.

Fire Safety

One of the biggest concerns we receive from the field about the use of battery installations is a so-called thermal runaway: a battery fire. With a thermal runaway an exothermic reaction (burning without oxygen) takes place in which the batteries heat up very quickly (>10 degrees/minute). The consequence of this almost unstoppable chain reaction is the melting or even exploding of the battery and the burning of the substances and gases that are released. It is important to emphasize that the chance of this happening in practice is very small. Various precautions are possible to minimize the risk of fire. With regard to fire safety, we use a way of working that is based on four main components: prevention, detection, fire fighting and impact limitation.

Prevention

The majority of fire safety measures are aimed at preventing a fire or other unsafe situations. Primarily, we only work with high-quality parts, which are selected and processed according to high standards. All these parts are equipped with necessary preventive measures and allow reading of errors and temperature.

The battery packs feature temperature, current and voltage monitoring at various levels and include fuses, mechanical isolation and pressure relief valves to prevent ignition and propagation. Once abnormalities have been identified, both the person responsible for the battery on site and Greener will be notified. The system will also shut down itself if this is necessary for safety.

Detection

In the unlikely event that smoke or heat does develop, there are several sensors and detectors that make it possible to take timely action. When they detect smoke or an increase in temperature, the system can shut down individual battery modules or the entire system. In this case the responsible person at the location and the control room at Greener are always notified that critical values ​​have been reached.

Extinguishing in case of a Fire

Should a fire nevertheless occur despite these prevention and detection measures, several measures have been implemented to prevent the fire from escalating. In the event of a fire, the battery immediately switches to de-energized and sends a notification to both the user and the Greener. De-energizing the power supply to the battery system must be done at the medium or low voltage installation at the battery. This is usually located at a safe distance from the battery and is therefore safely accessible. It is then possible to extinguish the fire safely. To prevent fire escalation, the batteries are designed to remain stable for as long as possible in the event of an incident, not self-ignite and thus prevent a thermal runaway in one cell from spreading to the next.

Cooperation with security services

We cooperate actively with fire brigades and other security services to share knowledge about the safe use of mobile battery systems. During these meetings we discuss the safety systems and especially what to expect in the event of an incident.
In the event of an incident, the fire service will always contact Greener and, in consultation, draw up an action plan on site to limit the impact of the incident.

General vision on safety: prevention is better than cure

The market for mobile batteries is growing rapidly. As a result, regulations lag behind practice in some areas. This sometimes raises questions about ​​safety. When it comes to the safety risks of mobile batteries, the fear of fire often comes up. It is good to emphasize that the chance of this happening is very small, partly due to all the preventive measures taken. Moreover, working safely with mobile batteries goes much further than fire safety alone: ​​from detailed instructions for safe installation to safety regulations and health and safety legislation. At Greener, we continuously think about the safety measures in our fast-growing market.

The most important principle here is that prevention is better than cure. This emphasis on prevention is reflected in the design of the batteries and the controlling software as well as in the various measurement and monitoring systems in the container and the battery itself. The arrival of the PGS-37 guideline is a good step forward and offers additional tools for safe handling of lithium-based battery systems. At the same time, the safe execution of projects also requires that all parties involved are aware of the implications of deploying a battery. From our point of view, this should be standard at any project where mobile batteries are used.