Initial Design Documentation
Table of Contents
This page documents the initial design, or feasibility analysis, for our WECEB project.
Visual Conceptual DesignFeel free to click the image to see a larger view.
Finding Power Needs
For power to CDPCWe will start off analysis with 8 batteries with P12402's designated Charge. Reference Reference R.2 shows us critical information about the LVE battery.
- Capacity: 3000 mAh
- Voltage: 7.2V
- Rapid Charge: 3000 mA for 1.5 hours
- Standard Charge: 300 mA for 12 hours
- P12402 Charge: 600 mA for 3 hours, 300 mA for 3 hours
1 Battery under P12402 charger (very conservative estimate) ===> (0.6A * 6hrs) = 3.6 Ah/battery
Their circuitry and regulator will be 87.2% efficient (see ISE Documents) so 2.7 Ah / 0.872 = 4.13 Ah/battery
The battery is charged at 12V nominal ===> 3.09 Ah * 12V = 49.54 Wh/battery
To get a total for 8 batteries, multiply 37.12 Wh by 8. 8 batteries ~ 396 Wh
That means the WECEB's battery bank needs to output 396 Wh so the CDPC can fully charge the LVE batteries. This can be seen in the ISE Documents page under Efficiency Spreadsheet.
Power From the Wind Turbine to Battery BankWith an 80% efficiency for a Lead Acid battery, we need to charge our battery bank at 396 Wh/0.8 which equals 495.4 Wh
It charges with a system voltage of 12 Volts, so in terms of Amp-Hours, (495.4 Wh/12) we need 41.3 Ah.
To find daily average supplied current from the turbine, divide by 24 hours; 1.72 A
Multiply average current by 12V to get daily average power needed from the turbine; 20.64 W
Sizing the Battery BankLooking at Reference R.1, we are able to determine the power consumed by charging the LVE batteries so we can rightly size our battery bank.
In order to size out Battery Bank, simply divide Amp-Hours from the previous step (41.3 Ah) by percent Depth of Discharge.
For a deep cycle battery, we don't want to discharge more than 60%. 41.3Ah/0.6
That means our Battery Bank needs to be roughly 68.83 Ah.
In all likelihood, we will buy a larger battery than 68.83 Ah. Days of autonomy, or days of no wind, should be included so the system can still work on calm days. The Amp-Hour capacities are simply multiplied by the days of autonomy. Two days of autonomy assumes one day of ample wind followed by one day of no wind.
Temperature effects come into play which will also require the battery to be larger.
Mission Statement | Stakeholders | Benchmarks | Constraints | Objective Tree | Customer Needs | Engineering Specifications
Work Breakdown Structure | Function Structure Diagram | Concept Generation | Concept Selection | Risk Analysis | Initial Design Documentation | Systems Design | Detailed Design