Wednesday, 26 October 2016

Several Reasons of Lithium Battery System Fires

Security is the lifeblood of child battery, the lifepo4 48v system from the inside out cause of the fire in recent thinking and analysis, this is considered a major reason for the layers to push forward, then consider the previous and future accidents put to match then the future of an accident PPM (parts per million) based on the actual design of each model speculation. Hereinafter all manufacturers names are removed, does not explore this topic for any enterprise, not judge.

It is assumed from a single problem, and then extended to the global dimension of the experiment, it can be seen:

Analysis of the whole system just to match the battery fire this extreme event occurs, we segment the contents from mechanical abuse, battery system design basis is to focus on in a relatively safe position of the vehicle, to prevent problems in the course of the vehicle the whole mechanical design of course is a lot to do experiments security content acupuncture, extrusion, etc., but in fact the problem caused by the mechanical abuse but easily become a problem.

In Tesla's two accidents as an example:

Lithium ion Battery Explosion

1. On fire in Smyrna, Tennessee, this car electric cars rushed to drop the road trailer hitch, the fire broke out after the collision chassis.

2. When the driver hit the turn, and through the wall of a cement eventually hit a tree and stopped the fire.

3. In Seattle, the owner called and hit a metal fragments, so he left the highway. After the failure of the car, he smelled the smell of burning, fire burning vehicle at this time.

This mechanical design also appears on a simple structure in the periphery of the bottom cover and consider additional protection, you can get immediate results.

We make things happen this year, the manufacturers removed, you can then think about a car on fire outside the cell or battery? A large part of the load cell is outside the peripheral portion of the cable overheating lit things some more.

Here we can be divided into three basic, because the nature of fire:

Released in accordance with the design intent and outside the combustion heat within the battery, 

1. The combustible gas inside the battery release ignition

2. Flammable liquid inside the battery release + Flash point: here including electrolyte leakage and coolant leaks in two parts.

We can release heat energy battery systems to consider:

1. Battery Pack or Battery Cell Overcharge

Overcharge release of thermal energy in general is indeed more common reason, the storage battery pack of solar powered portable generator level thermal runaway event, can be broken down into more down the battery (modules monomer overcharge), evaporated electrolyte battery overcharge and overheating, as well as It is the battery remaining capacity (SOC) calculation error caused by over-charging, high SOC state, not in accordance with energy recovery protection cause, and the charging control program stuck due to overcharging.

2. A Person Short Circuit Overcurrent Heat Release

Lithium Battery Explosion

Battery pack high voltage circuit failure cause a short circuit, distributing heat. The main battery pack is an internal short circuit and external short circuit, causing the conductors and connectors overheating, caused by overheating of the monomer subsequent thermal event, is further broken down to be broken down into short-circuit caused by overheating of the module components. Eg short circuit module level, a short circuit within the battery pack, the external corrosion / conductive liquid into a short circuit caused.

3. High-impedance Connection of Heat

Fault battery pack high-voltage circuits, resulting in high resistance appearing at the position charging and discharging circuit, the current rise in the temperature of the high resistance point that could cause a fire and subsequent heat adjacent material spread. Trunk junction poor contact, corrosion caused by heat.

4. The Internal Resistance of The Battery Overheating and Internal Promotion

Monomers to produce a combustible gas exhaust, followed by a heat source (arc monomer thermal runaway) lead to the battery system, surplus heat. Monomeric single point of failure as defined thermal runaway experiment can be considered a single monomer extended to the whole aspect, in the given conditions, each battery pack for portable solar power generator will achieve record correspondent, some reference to the role, but the experimental conditions and the occurrence of failure is not It may be completely consistent.

The article comes from http://www.storagebattery-factory.com/news/several-reasons-of-lithium-battery-system-fires.html.

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