Project 1 Mechanical design of battery pack

Aim:

To Prepare a detailed battery pack drawing along with its enclosure, with the given parameters.

Given:

- Battery pack capacity: 18 KWh

- Cell: ANR26650M1-B

Introduction:

* An electric battery is a device that makes the use of either single or assembly of electrochemical cells that are meant to be stored in as chemical energy and converting into electrical energy

* Each cell has positive terminal and negative terminal namely cathode and anode.

* The individual cells are connected in various combinations as series and parallel to get the characteristics of the battery.

Battery Pack:

* A battery pack is the set of batteries or individual battery cells.

* They maybe arranged into either series or parallel depending upon the voltage required.

* Rechargeable battery pack consists of temperature sensor, which the battery charger used to detect the end of the charging.

* Interconnects are also found in the battery as the parts are connected into the each cell, used to connect between the cells.

Advantages of battery pack:

* Can be swapped easily

* Flexibility of the design and implementation is easier

* Easy to recycle and hence reduce the wastage.

Some Basic terminoligies of the battery:

Volt - The unit of measurement of electromotive force, or difference of potential, which will cause a current of one ampere to flow through a resistance of one ohm.

Voltage, cutoff - Voltage at the end of useful discharge.

Voltage, end-point - Cell voltage below which the connected equipment will not operate or below which operation is not recommended.

Voltage, nominal - Voltage of a fully charged cell when delivering rated current.

Direct Current (DC) - The type of electrical current that a battery can supply. One terminal is always positive and another is always negative.

Discharge - The conversion of the chemical energy of the battery into electric energy.

Depth of Discharge - The amount of energy that has been removed from a battery (or battery pack). Usually expressed as a percentage of the total capacity of the battery. For example, 50% depth of discharge means that half of the energy in the battery has been used. 80% DOD means that eighty percent of the energy has been discharged, so the battery now holds only 20% of its full charge.

Cells for making Battery Pack:

Nanophsphate High power Li-Ion cell:

* A123 higher performance Nanophosphate Li-Ion Battery delivers high power and energy combined with higher safety performance and extensive life cycling with light-weight,more compact package.

* The given cells have low capacity loss and impendance growth over time as well as higher usable energy over a state of charge, allowing the systems to meet the end of the power and energy requirements with minimal pack oversizing.

Technical Data:

Battery Holder:

* A battery holder is made up of PC/ABS providing the combination of high processability of ABS(Aconitryle Butadiene Styrene) with excellent mechanical properties, impact and heat resistance of PC.

* It is heat resistant, crack resistant and making it good for holding the multiple cells in close proximity, where heat is caused by the current. This allows operation in wide temperature range.

* High stiffness allows the battery pack to be compact and high dimensional accuracy. They can be 3D printed or made from traditional processes such as injection moulding which gives higher accuracy with minimum finishing requirements.

* This is made with the minimum distance of 1 mm to 4 mm in the middle in the middle of the battery packs as in the place of heat generation would be maximum in all direction. The gap is given to prevent the dangerous situation for the prevention of explosion of cells.

Designing of Battery cell:

Nickel Strips:

Nickel strips are used as the battery connectors because they have 20-30% more conductivity than other materials. The manufactures look for high conductivity because it allows them to produce batteries in different sizes and shapes. That too, without worrying about the capabilities of the battery to handle power and heat.

Properties of Nickel Strips:

Due to its capabilities of holding multiple properties, Nickel use in different applications. Some of them are: