Analysis of Thermal Performance of High-power Lithium Battery Chargers -- To Improve Charging Efficiency and Safety

With the rise of motorcycle electrification trend and the widespread popularity of various types of electric scenes, the market demand for medium and high-power lithium battery chargers is experiencing rapid growth. In this context, the heat dissipation of the charger has become the focus of attention in the industry. High temperatures not only reduce charging efficiency, but also may lead to safety risks. In order to maintain the heat dissipation performance of high-power chargers under continuous operation, this paper will discuss the key technologies to achieve efficient heat dissipation from the comparative analysis of heat

I.The core mechanism of fan cooling: three principles of air duct design

During the operation of a high-power charger, its internal components (e.g., metal-oxide-semiconductor field-effect transistors (MOSFETs), transformers) will generate significant heat energy. If the heat dissipation mechanism is not adequate, it may lead to a reduction in charging efficiency, and in serious cases, it may even accelerate the aging of the components or cause a fire. In the following, we will analyze the advantages and disadvantages of three commonly adopted heat dissipation strategies.

1. Natural Heat Dissipation: Simple but less efficient

    Principle: Mainly relies on natural convection of air and radiation on the surface of the housing.

    Advantages: Simple design, no noise generation, no additional energy consumption.

    Disadvantages: Lower cooling efficiency, only suitable for low power (<500W) applications.

2. Heat sink: passive enhancement on the basis of natural heat dissipation, but still has limitations

    Principle: Enhance the heat dissipation performance by increasing the surface area of the heat sink or adopting materials with high thermal conductivity (e.g., aluminum alloy).

    Advantages: Simpler structure, better heat dissipation than natural heat dissipation.

    Disadvantages: Larger in size, cooling efficiency is significantly affected by the ambient temperature, and it is difficult to cope with continuous high power loads.

3. Fan cooling: As an active cooling method, it is considered to be the “ultimate solution” for cooling.

    Principle: The fan is used to force the airflow to rapidly remove the internal heat.

    Advantages:

    1）Efficient cooling: Compared with natural cooling, the temperature can be reduced by 30%-50%, which can easily cope with the demand of high power over 1000W. o Compact size: No need to use a large, compact, and easy-to-use cooling system.

    2）Compact size of equipment: No need to use large heat sinks, which helps to miniaturize the design of the equipment.

    Industry Trend: Over 90% of industrial grade high power chargers have adopted fan cooling solutions.

Ⅱ. The core mechanism of fan cooling: three principles of air duct design

Fan cooling performance is not only limited to the performance of the fan itself, but also closely related to the air duct design. Poor air duct design will cause airflow turbulence, significantly reducing cooling efficiency. The following are the “golden rules” of air duct design proposed by our team.

1. Keep the air inlet away from the heat source: Prevent the phenomenon of "hot air circulation"

    Problem: When the air inlet is too close to the heat generating components (e.g., transformers), the inhaled hot air will cause the components to be heated twice, resulting in a vicious cycle.

    Solution:

    1）Locate air inlets in cooler areas of the equipment (e.g., sides or bottom) to ensure that cooler air is drawn in. o Make sure that the layout of the heating element is not too close to the heating element (e.g., transformer).

    2）Optimize the layout of the heating element so that it is isolated from the air duct to avoid interference with the airflow from the heat source.

2. Duct design “short and straight”: Reduce airflow resistance

    Problem: Long and winding ducts increase airflow resistance, slowing down air speed and leading to heat buildup.

    Solution:

    1）Adopt a straight duct design to shorten the airflow path.

    2）Build internal components downward to ensure unobstructed airflow at the top of the product.

3. Precise Directional Heat Dissipation

    Problem: If the layout of heat generating components is scattered, it is difficult to effectively cool the key heat generating components.

    Solution:

    1）Reasonable distribution of heat sources during PCB Layout.

    2）Utilize the synergistic effect of fans and air ducts to accurately direct the airflow to high heat areas (e.g., MOS tubes, inductors).

Ⅲ. Case Study: How does 1300W high efficiency heat dissipation enhance product value?

    Temperature Performance: Under 120Vac & 220Vac input full load operation, the maximum ambient temperature of the product can reach 50 degrees Celsius, which meets the temperature requirements of most countries and regions around the world.

    Life performance: For every 10°C reduction in the operating temperature of components, the theoretical lifespan doubles.  Under 25℃ ambient temperature, the lifetime of the product can be up to 89000Hours.

    Safety: IP65 protection + flame retardant materials, eliminating the risk of short-circuits and fires caused by high temperature.

Ⅳ. Choose us, choose “cool” charging experience

Inventronics high-power lithium battery charger, with fan cooling + intelligent air duct design.

    High-efficiency heat dissipation: Support 1300W continuous output, the temperature is always better than the industry standard.

    Durable: Fully sealed dustproof structure and excellent thermal performance.

    Safe and reliable: all-round protection, more reliable use.