Project 2 Thermal modeling of battery pack

For a 10 cell series lithium ion battery model, simulate the thermal effects and compare life cycle performance at various temperatures, charge & discharge rates using MATLAB.

Battery has a major problem of temperature and it's temperature plays a vital role in the life cycle of the battery, they are configured in series and parallel ways and depedning and they should be fixed and space should be easily available so that they can expand. heting them at high temperature is also a bad idea so we have to keep focus on there temperature.

When temperatures increase this affects the chemical reactions that occur inside a battery. As the temperature of the battery increases the chemical reactions inside the battery also quicken. At higher temperatures one of the effects on lithium-ion batteries’ is greater performance and increased storage capacity of the battery. A study by Scientific reports found that an increase in temperature from 77 degrees Fahrenheit to 113 degrees Fahrenheit led to a 20% increase in maximum storage capacity. However there is a side effect to this increased performance, the lifecycle of the battery is decreased over time. In that same study, it was found that when the battery is charged at 113 degrees versus 77 the lifecycle degradation was much more significant at the higher temperature. For the first 200 cycles the battery performance only degraded 3.3% at 77 degrees; at 113 degrees the performance decreased by 6.7%. That’s more than double the amount of degradation! Based on the greater degradation at higher temperatures, the battery lifecycle can be severely diminished due to consistent exposure to extreme heat. While heat exposure does temporarily increase battery capacity the damage that it does to the lifecycle can cause long term problems and prolonged heat exposure should be avoided.

A brief review ten series cell battery and it's discusssion overit how temperature is affecting it's battery life-

In this battery are connected in series and they are managed by controlled current source and square wave generator send the current signal to battery and soc,current,voltage, age, maximum current, ambient tempertaure amd cell temperature is calculated basically age is a cycle, one cycle means full charge and dischargeand the battery are connected in series means one's battery positive is connceted to other battery negative and doing this 10 series battery are connected one parallel.

blocks used for completing this circuit-

we can generate this square waveform depending upon the amount of frequency or time period and i have choosen frequency and it's unit is hertz and the frequency simply says the amount of time required for one full cycle.

we are taking amplitude value of 5.4amp and time period of one cycle is 7200sec and this is for for first case other caseshave different values.

contolled current source-

This generates current depending upon our input and the current cycle is generated.

Battery configuration-

In this battery cycle the battery has configured to aging and temperature with soc .

here we have taken battery nominal voltage of 3.7v and totla battery voltage is 370 volts and intila charge is 0 and soc of tha battery is zero obviously first we charge the battery and then discharge the battery and this model battery run for 10 hour for which it runs for 5 cycle and in each cycle it charges and discharges.

first case of battery - ambient temperature of 25degree and charge and discharge current is 5.4 ampere

Results-

]

In this cycle battery has been charged and discharged in 5 cycles and it's charging and discharging in 5 cycles and amibent temperature is 25 degree and the temperature of the cycle temperature maximum of 29 degree and it settles down at 28 and it's it temp at 20 degree which has beeen increased to 28 and age of the cycle is 4 due to temperature affects.

2nd case is temperature at 35 degree ambient and battery temperature at 20 degree and 5.4A

In this case also batterry is charging and discharging and this occurs for 5 times and battery capacity has been reduced and cells max temp is 35 and it has settled at 33 and age is almost of 4.3 cycles.

3A and at 35 degree-

Here there is increase and decrease in discharge and battery is not getting fully charged it's soc has increased to only 55percent cells temperature has not reached to 35 and it has reached only 30, and age has reached to 1.5.

3A and 40 degree-

In this case battery temperature is at 20 degree and surrounding temperature is at 40 degree and soc is increased to only 55 percent and discharge and charge current is 3ampere, and age is reached to correct to 1.5 and cells temperature has reached little more than 40 degree.

So in all this case as ambent temperature increases cells temperature increases and battery soc is decreasing with discharge and charge current decrreasing.

temperature plays important role as more is the temperature more it can cause damage to the cell.