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How to Choose Electric Vehicles LifePo4 Batteries Pack

Author: Source: Datetime: 2016-10-12 16:53:53
Electric vehicle lifePo4 battery pack used must have a high performance, low-cost, long life, safety and high performance. lifePo4 batteries are most likely to meet these challenges. At present, all over the world are doing the appropriate research and development to improve the characteristics of the lifepo4 batteries. But even the best performance of the battery, a combination of poor battery pack may also lead to the overall performance of the battery pack, reducing the life, safety deteriorated and led to increased costs.

Battery safety

Security is the largest lifePo4 batteries concerns. In abuse trials, over voltage, over charge, over discharge, overheating, nail puncture, external short circuit, or internal short-circuit defect so may lead to thermal runaway and battery electrolyte leakage, smoke, hole, fire or even an explosion. For the application of the battery on the vehicle we should be strict requirements. Although by improving the battery positive and negative material, adding additives to improve performance and safety through effective electronic and mechanical controls virtually eliminate or significantly reduce the possibility of accidents, but because of the squeeze as well as overvoltage and thermal runaway caused by internal short circuit still requires special attention. It should therefore be targeted on the lifePo4 batteries pack accordingly designed to reduce the impact of these circumstances, improve the security of the battery pack.

E-bike Battery Pack
Cylindrical and prismatic battery of Comparative monomer

Using cylindrical lithium ion secondary battery unit cell and prismatic (or laminated board) single cell lifePo4 batteries is a difference. Cylindrical single cells can be mass-produced and has a high quality. However, with various types of vehicles can be loaded with a battery pack space form factor changing needs, the cost advantage is reduced. The cylindrical design of rugged and robust construction, particularly anti-hammering, shock and vibration, to prevent accidents. With wound cylindrical unit cell area becomes large, the surface area of the inner layer wound area than its exterior heat that can be relatively reduced; therefore, the heat transfer capacity decreases and the temperature gradient increases. Surface area and internal prism or laminated board design with high heat externally stacked around the floor area ratio, easier thermal management. And prismatic cylindrical single cells than the cells to provide higher volumetric packaging efficiency. However, if the prismatic single cells using a soft film packaging must also be taken into account in the design to prevent local stress, hammering resistance, shock and vibration. Corresponding facilities may increase the volume and weight, reducing the volume of soft film packaging advantages prismatic unit cell.

Battery Thermal Analysis

Thermal management is critical to the battery for optimal performance and longevity at low temperatures and high temperature environments. High temperatures reduce the lifePo4 batteries performance and life, thereby limiting the vehicle driving range (driving range) or performance. Thermal management system of the battery at low temperature heating at high temperature for cooling the battery to cool. Thermal management of the corresponding cooling and heating systems increases the cost, weight and volume of the battery pack. Our solar powered portable generator also need the lithium batteries. Thermal management is not only to maintain the maximum temperature of the lifePo4 batteries is below the limit, but also to maintain the temperature uniformity between the cells. To improve battery pack thermal field balancing, this temperature changes need to fluctuate within a small range (for example, less than 5 ℃). Therefore, we in the design of the battery pack, lithium ion batteries must be reasonable to select the type according to the thermal characteristics of the lifePo4 batteries, and for the balance in favor of the principle of reasonable thermal design of the battery pack cooling system thermal management structure. While ensuring that the designed system has a simple structure, reliable and durable, low-cost and low parasitic power and other characteristics.

We can see that the selection of the lifePo4 batteries have a great impact on the performance of the lifePo4 batteries pack, in severe cases can lead to decreased performance of the battery pack, higher costs, and the like having a security risk. But also an urgent need for the battery manufacturer's concerted efforts to create the most suitable lifePo4 batteries for electric car use.
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