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The Stages of a Lithium Ion Battery Failure

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Lithium-ion (Li-ion) batteries are used in a variety of applications. They can be used to power anything from small portable devices to vehicles and backup power systems. Li-ion batteries provide high-capacity energy storage and can release energy in a very controlled manner. It is for this reason that they are becoming increasingly popular for many different types of applications.

Li-ion batteries are now commonly used in call centres, data centres and a variety of other applications that require battery backup. In these situations, a series of Li-ion cells are connected together to meet the power requirements of the application and mounted in racks that can take up all or part of the dedicated space. 

However, there is a downside to Li-ion battery arrays. Li-ion batteries contain flammable electrolytes and, if incorrectly charged or damaged, can lead to explosions or fires. Once a single cell overheats, other cells in the rack can easily fail and ignite, causing a catastrophic domino effect. 

Fortunately, there are sophisticated monitoring systems that are available to monitor the condition of Li-ion batteries and detect any failures or fires at the earliest stages.

The Stages

There are several stages to Li-ion battery failure. It is these events that allow us to detect failures during the initial stages so that potential fires can be prevented before too much damage is caused.

Stage 1 – Initiation Abuse Factor
Li-ion battery failure is started by some form of electrical, thermal or mechanical abuse. At this stage, failure is typically detectable by a battery management system that constantly monitors the physical characteristics of the individual Li-ion cells.
The amount of time between stage one, the initiating abuse factor and stage two, off-gas generation, is largely down to the type of abuse that battery has suffered. For mechanical abuse, where the battery has been physically damaged, stage two often occurs immediately. For abuse factors such as thermal or electrical abuse, stage two can occur anywhere from 30 minutes to several hours after the initiating abuse factor.
Stage 2 – Off-gas Generation
The second stage of Li-ion battery failure is off-gas generation; as the battery begins to fail, electrolytes break down and generate gas that is released from the cell in an off-gas event. There are different reasons why this occurs, mainly depending on the form factor of the battery; cylindrical cells generate off-gassing compounds because of a vent feature of the lithium-ion battery cell, while in pouch cells there is a rupture in the seal which leads to an off-gassing event. This stage occurs before thermal runaway; a situation where an increase in temperature changes the conditions in a way that causes a further increase in temperature.
Stage 3 – Smoke Generation
If no action is taken during the off-gas event, the next stage is smoke generation. This is an indication that the cell has reached the stage of thermal runaway and that the cell can experience rapid disassembly at any moment. The smoke is produced inside the cell. As the cell has already experienced a vent or rupture from the off-gas event, the smoke is able to escape the battery and will be detectable by smoke detectors.
There is typically little to no time between stage three and stage four. Therefore, smoke generation would not usually provide enough warning of failure before fire occurs.
Stage 4 – Fire Generation
Once stage three has occurred, the battery is in an extremely vulnerable state and can catch fire or explode at any moment. The cell has entered a full state of thermal runaway and is generating its own heat. As these cells decompose, they generate their own oxygen, further fueling the fire. As one cell fails, it can cause other cells in its proximity to fail creating a very large and destructive event.

Battery Monitoring System

Usually, by the time smoke generation occurs, a fire event is imminent. Allowing cell failure to reach this stage leaves little time for potential fires to be dealt with before it becomes out of control and causes irreversible damage. A fire of this nature can be extremely dangerous, causing serious injury, damage to property and can render a building inoperable for a considerable amount of time. 

Battery monitoring systems are used to detect battery failures during the early stages. By detecting off-gas events, they allow plenty of time for potential failures to be investigated and dealt with before a fire breaks out and it becomes a catastrophic event.

Li-ion Tamer Introduction

The Li-ion Tamer is a reliable and sophisticated battery rack monitor that provides a very early warning of battery fire. 

The Li-ion Tamer is used to detect the gas that is released during the off-gas event that occurs during the early stages of Li-ion battery failure. This means that failures can be detected and dealt with before the smoke or fire stages to provide the best chance of successful intervention.

There are three key components that make up the Li-ion Tamer rack monitor system: a controller, a monitoring sensor and a reference sensor. 

Monitoring sensors are installed outside of the battery racks to monitor for off-gas events. When the monitor sensor detects an off-gas event it sends a signal to the Li-ion Tamer controllerReference sensors are placed around the racks to monitor the ambient environment to cancel common mode signals and reduce nuisance alarms. 

Why Choose Eurofyre?

Complete System Supplier
Eurofyre manufactures and supplies all aspects of fire detection and its associated safety products, including battery rack monitoring systems, and can provide expert advice and consultation.
Demonstration and Training
We offer demonstrations and expert training on a range of systems, including Li-ion Tamer rack monitoring systems, in our very own sophisticated training facility.
After-Sales Support
Eurofyre offers both on-site and telephone support to assist you in ensuring that your system is fully functional and operating at maximum efficiency. Our after-sales care and support are second to none.

For more information about Li-ion Tamer Rack Monitoring systems, or to discuss any of the other products that Eurofyre has to offer, please feel free to get in touch either by phone on +44 (0) 1329 835 024, by email to sales@eurofyre.co.uk or via the online enquiry form situated on our contact page.

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