Battery Pack

BATTERY PACK

Battery pack generally refers to a collection of batteries that are assembled together to provide more power. Battery packs can be used in various applications such as in electric vehicles, power tools (or) as part of larger systems. They can be designed for specific voltages and capacities based on their intended use.

1. Construction of battery pack

Generally a battery pack is merely a bunch of batteries, connected in series (or) parallel configuration, with one positive and one negative terminal. It also includes a thermal management system, a battery management system, a mechanical structure and enclosure as well as high voltage and low‒voltage wiring harnesses and connections.

2. Battery pack design of electric vehicles

Battery packs have different designs involving electrochemical, mechanical control and thermodynamic principles. For EVS applications, many individual cells are stacked in a specific order for making the interconnection between batteries for power flow. Battery packs are very expensive, especially for EVS applications due to a high number of cells.

Steps involved in battery packs design

The battery pack design consists of many steps such as

Step 1: Select the battery cell technology and the pack specifications by battery sizing.

Step 2: Battery pack designing (electrical, control and structural)

Step 3: Battery pack safety and testings.

For the battery to be used, the primary parameter is the energy density of the cell, which decides the driving range, speed and acceleration of the vehicles.

Important calculations required for battery packaging

Battery packaging required some calculations, which are discussed in the following steps.

Step 1: Calculation of battery voltages

The essential requirement of any vehicle is maintaining the required voltage during the operations. The required voltage can be obtained by connecting the multiple cells in series and the voltage can be calculated

V = nv

V= Voltage of the battery

n = number of cells

v = cell voltage

Step 2: Calculation of battery pack size

The battery pack size (S) can be calculated by

S = VA'

where,

V = Voltage (obtained from above equation)

A' = Ampere rating of the cells

Step 3 Calculation of weight (W) of a battery

Weight (W) of a battery can be calculated by

W = SC

Where, S= pack size (obtained from above equation)

C = Capacity of the battery (known in W.h/mile)

Step 4 Calculation of battery range

The battery range (R) is calculated by

 R = S/V

 S = Pack size

 C = Capacity of the battery

Step 5 Calculation of battery power

The power required, delivered by the battery, for moving a vehicle can be calculated by

where,

P_DC = DC energy usage of an vehicle (in W.h/km)

η_d = Overall constant efficiency

P_aux = Power uses of the auxiliary system

F_x = Force required to move the vehicle

v = Energy consumption.

After calculating the above parameters, an extra 19% is added to the battery capacity. This is due to the reason that only 81% of the battery capacity is normally utilized and the efficiency of battery charging is considered to be only 81%.

3. Applications of battery packs in different fields

Battery packs are used in a wide range of applications from powering portable electronics to providing backup power for critical systems. The main applications include.

1. Customer electronics

Battery packs are used to provide power to laptops, smartphones, cameras, toys, portable audio players.

2. Industrial applications

It also provides power to fork lifts, uninterruptible power supplies (UPS), Remote monitoring system, robotics.

3. Medical devices

It provides power to portable monitoring equipments like ECG machines, vital sign monitors, hearing aids, wheel chairs, life support systems.

4. Transportation

It provides power to electric vehicles (EVs) (like electric cars, buses, motor cycles, scooters etc).

5. Renewable energy systems

Battery packs are essential for storing energy, generated from renewable sources (like solar power systems, wind power systems)

6. Other applications

Power packs are used to power emergency lightings, security systems, military applications, cordless tools, etc..

4. Advantages and disadvantages of battery packs

Advantages

1. Primary advantage is portability and convenience.

2. It stores energy for later use and provide backup power during outages.

3. Batteries store excess energy, generated from solar panels (or) wind turbines, making renewable energy more reliable.

4. Batteries can help reduce energy costs by allowing users to store energy during off‒peak hours and use it during peak hours.

5. It reduces the consumption of fossil fuels and lower green house gas emissions.

Disadvantages

1. Battery packs are expensive to purchase.

2. Lifespan is limited.

3. Manufacturing process (extraction of raw‒materials) have significant environmental problems.

4. Improper disposal also can lead to environmental risk.

5. Extreme temperature can affect its performance.

6. Charging of battery packs will take more time.