PFR - Aerospace Engineering Sciences Senior Design Projects ...

Project Final Report – CUDBF April 30 th , 2009
ASEN 4028: Aerospace Senior Projects
Table 19: Battery Options
NiCad Sanyo
KR 1400AE
NiMH Intellect
IB 1400
Weight (g) 31 27
Internal Resistance (mΩ) 10 4
Maximum Continuous
Discharge (amps)
10 20
In all categories, the NiMH battery chemistry outperformed the NiCad battery for this
application. Therefore, NiMH chemistry battery cells were chosen for the aircraft.
With the battery chemistry chosen, several specific batteries were analyzed in a trade study to
choose the exact battery cell. The battery needed to be able to discharge up to 40 amps of current
continuously, with 80 amps in short bursts. The most important factor in choosing the battery
was energy density. Four top of the line 1.2V NiMH batteries were analyzed in the trade study
provided in Table 20. The Elite 1500 battery was chosen because it had offered the most
capacity at the least weight.
Table 20: NiMH Battery Selection
Image
IB 1400 Elite 1500 Elite 1700 GB 2000
Capacity (mAh) 1400 1500 1700 2000
Weight (grams) 27.5 25 28.5 36.5
Density (mAh /g) 50.9 60 59.6 54.8
The battery pack was sized in order to meet two requirements; 100ft takeoff and four lap range
with full water bottle payload weight. In order to generate the required thrust in order to make
the 100ft takeoff, the battery pack must be able to generate 1200W of power. The battery pack is
capable of discharging at up to 80 amps if it is taken directly off the charger and used within 10
minutes of being charged while it is still hot. However, due to the unknown timing of the
competition flight line, there may be up to a 30 minute wait from when the battery is taken off
the charger until takeoff. That would limit the maximum amp draw to approximately 60 amps.
Using the equation P=I*V, the battery pack voltage for takeoff must be at least 20V. Assuming
€
101