Battery and Regulators
By: Mesfer Aldosari
Micro biped will use two batteries LIPO 2S 350mAh to supply power to the robot.
So after calculating the total current that is required to operate all of the component, the project needed 5 v minimum to run our project and 1500 mAh if the project was going to be ran for one hour. However, since the goal is to simply complete a track the mAh of the battery can be lowered.
So that means the project needs a battery that can provide at least 5 volts and provide enough current to power the device. In addition to providing enough power the batteries need to light enough to allow the servos to move.
2S Lipo battery
*Click on the link above to see the specifications at Hobby People, the following information was taken from there.
Features:
- It has light weight which is about 28g
- Maximum discharge rate at 10 Amps
- Maximum pack voltage at 8.4V, Minimum pack voltage at 6V
- Its dimension: 8 x 31 x 2
- 7.4 volt
Capacity: 350mah
Voltage: 2S/2Cell/ 7.4V
Weight: 28g
Lifetime of the battery:
Battery Life = Battery Capacity in Milli amps per hour / Load Current in Mill amps * 0.70
[Battery capacity(mAh)/device consuption(mA)]*0.7
(350/1500)x0.7 = 0.1633
0.1633x60x2= 19 minutes is our battery last long
The factor of 0.7 makes allowances for external factors, which can affect battery life.
19 minutes without the power lost it is going to be 28 minutes
The formula used was taken from Digi-Key.com, at this link.
Regulators:
Micro biped will need to use at least one voltage regulator to drop the voltage down to 5 volts from the 7.4 volts a LiPO battery provides. To do this two LM 7805s, made by Fairchild, were chosen. The LM7805 will take in 7V – 30V and has an output of 1.5A, so theoretically the LM7805s should be able to give out enough current to power the devices.