1. What's the purpose and basicprinciple for lithium ion battery pack design?
Accordingto the requirement of device, battery design provides the most usefulperformance of power supply or motive power sources for it. Therefore, firstly,battery design must meet the use requirement of device and then to optimize tohave the best overall performance which can confirm the battery electrodes,electrolyte, diaphragm, housing and other components. Next, matching themproperly and producing a battery or battery pack with certain specification andindex.
2. What kind of parameters are needed to buy a battery pack?
The battery design is designed to meet therequirements of the object (user or instrument). In this case, before designingthe battery, we need to know the object requirement for battery performance anduse condition. Generally include the following aspects:
① Theworking voltage of battery;
② Theworking current of battery, that is normal discharge current and peak current;
③ Theworking time of battery, including continuous discharge time, service life andcycle life;
④ Theworking environment of battery, including the working state and ambienttemperature;
⑤ Thebiggest size of battery allowed
In the meantime we should consider materialsource; battery performance; determinants of battery characteristics; batterytechnology; economic indicators; environmental issues and other factors.
What's the steps to design a li-ion battery pack?
After confirmingthe design assignment and fully prepared, the battery designer can start thedesign. According to the battery user requirements, there are two design ideas:One is provided the rated capacity of power supply for electrical equipment, anotherone is for specified dimension of power supply to research and develop goodperformance of new specification battery and special-shaped battery.
The design step ofdetermining the capacity battery
① Decidethe number of single cell of battery pack, the operating voltage and operatingcurrent density of cell.
② Accordingto the user requirements to determine the battery operating voltage, operatingcurrent and other indicators, select the battery series, with reference to theseries of "voltammetry curve" (empirical data may be got from experiments)to determine the operating voltage and operating current density of singlecell.
③ Decidethe number of cells of the battery pack
Number of singlecell=total operating current/single cell operating current
④ Calculatethe battery capacity
⑤ Calculatethe rated capacity in accordance with the required operating current andoperating time.
Rated capacity=operatingcurrent*operating time
⑥ Decidethe design capacity
Design capacity=ratedcapacity*design factor
Design factor is set toensure the reliability and service life of the battery, generally take 1.1-1.2