1. Lithium Polymer Charging Through Conduction
Breaking down the Procedure

2. A.R. Drone 2.0 1000mAh Battery Back Label on our Battery
Storage Capacity = 1000mAh
Total Nominal Voltage = 11.1V
Nominal Voltage = 11.1/3 = 3.7v/cell
Fully charged = 4.2v/cell
Minimum safe charge = 3.0v/cell
C (Discharge Rate) = The fraction of an hour it takes to discharge. 1 C discharges the battery in 1/1 hours. 10C discharges the battery in 1/10 hours. 1000mA in 6 minutes.
S stands for Series. Along with ‘3’ represents 3 cells in series. 3 cells in series is then written 3S.
P stands for Parallel. No Cells are in parallel in this case.

3. Battery Damage Temperature Overcharging: Rapid Charging Undercharging
- Capable of operating right up to 60ºC or 140ºF, and conversely, don’t work very well in cold temperatures.
- If the battery gets hot, battery life is decreased.
Overcharging:
Cells over 4.2V or 12.6V (3x4.2V/cell) are ‘overcharged’.
-Overcharging can significantly decrease lifespan of the battery and potential explosion.
Rapid Charging
- Can cause swelling similar to overcharging
1C Charging Rate standard.
Causes rapid temperature increase.
Undercharging
- Reducing the cells under 3V decreases battery lifespan.
- Reducing to 2.5V causes permanent and sometimes fatal damage.
Damaged Lithium Polymer Battery – Swelling caused by overcharging.

4. Lithium Polymer Charging Restraints
Single Cell Charge
Cell voltage is quickly brought to its nominal value (3.7V).
Cell is rapidly charged (1C Rate) for approximately an hour.
Charge current then decays as capacity increases logarithmically towards 100%.
This decay is to avoid overcharging and to also avoid overheating.
Source:

5. How Quickly Can the Battery be Charged?
It is possible to safely charge from
~15-20% To
~80%
If temperatures remain under 65 Celsius.
Theoretically:
1C at 1000mA/h would take ~1 Hour
It is unsafe to charge from 0% to 100% at a constant current
An excessive flow can dislodge particles of active material from the positive plates, resulting in reduced battery life.

6. Cell Charging

7. 7805 3-Terminal Adjustable Regulator
Why do we need a regulator?
The output of AC/DC conversion will be variable, adds stability.
Bring voltage to appropriate operating range.
Capable of supplying up to 1.5 A over an output-voltage range of 1.25 V to 37 V.
It requires only two external resistors to set the output voltage.

8. Typical AC to DC Rectifier
Mains-frequency regulated transformer supply
Example of an AC to DC conversion circuit (a generic schematic)

10. Initial Pspice Simulation Testing

11. Initial Pspice Results using Flooded Cells
This design only incorporates a constant charging current but will insure that all cells are being charged at the same rate.
Further design adjustments will incorporate a stepdown and cutoff switch for end charging.

12. Problems with this Design
Charging current sensitive to temperature variation
Charging cutoff not yet incorporated
Does not include a reduced charging phase (I, III)
Solution:
A controller can be implemented to control these issues

13. This picture was taken from a product catalog and is only being used in this presentation to demonstrate current market available controllers, specifically for battery charging.
Many options are available and are currently being looked into.
We are primarily looking for a controller that can adjust for temperature and supplied the need step downs/cutoff.

14. Future Considerations
Increasing battery storage increases weight but the increased storage can increase operating times
8-10 minutes flying (1000mAh)
12-18 minutes flying time (1500mAh)
20-30 minutes of flying time (2000mAh)
These estimates are supplied by Parrot under product specifications. Realistically we will not exceed the minimum estimations above.
Source: Parrot Website