Lesson test: The power system, battery to current

1.[1p]
A 6S lithium pack is fully charged. With each cell at 4.2 V, what is the pack voltage, in volts?

CorrectNot quite: 25.2

2.[2p]
A 1300 mAh pack is rated at 100C. What is its maximum safe discharge current, in amps?

CorrectNot quite: 130

3.[2p]
The main reason to build a craft at a higher cell count, such as 6S instead of 4S, is that

the same power is delivered at lower current, so the wiring and ESCs run cooler

Correct

the battery lasts more charge cycles

The answer is: the same power is delivered at lower current, so the wiring and ESCs run cooler

the motors weigh less

The answer is: the same power is delivered at lower current, so the wiring and ESCs run cooler

the propellers can be smaller

The answer is: the same power is delivered at lower current, so the wiring and ESCs run cooler

4.[2p]
Voltage sag under heavy load happens because

the pack has internal resistance, and current through it drops voltage inside the cells

Correct

the charger did not fill the pack

The answer is: the pack has internal resistance, and current through it drops voltage inside the cells

the motors are too efficient

The answer is: the pack has internal resistance, and current through it drops voltage inside the cells

the wires are too thick

The answer is: the pack has internal resistance, and current through it drops voltage inside the cells

5.[3p]
A quadcopter hovers at 9 A on a 5000 mAh pack. Using 80 per cent of the capacity as usable, roughly how many minutes can it hover?

CorrectNot quite: 27

6.[2p]
Resistive loss in the wiring grows with the square of the current, which is why the main battery leads are the thickest wires on the craft.

True

Correct

False

The answer is: True

7.[2p]
A low-ESR capacitor is often fitted across the battery input because it

absorbs the voltage spikes the switching ESCs throw back down the leads

Correct

increases the pack's capacity

The answer is: absorbs the voltage spikes the switching ESCs throw back down the leads

raises the battery voltage

The answer is: absorbs the voltage spikes the switching ESCs throw back down the leads

filters the radio signal

The answer is: absorbs the voltage spikes the switching ESCs throw back down the leads

1.[1p] A 6S lithium pack is fully charged. With each cell at 4.2 V, what is the pack voltage, in volts?

2.[2p] A 1300 mAh pack is rated at 100C. What is its maximum safe discharge current, in amps?

3.[2p] The main reason to build a craft at a higher cell count, such as 6S instead of 4S, is that

4.[2p] Voltage sag under heavy load happens because

5.[3p] A quadcopter hovers at 9 A on a 5000 mAh pack. Using 80 per cent of the capacity as usable, roughly how many minutes can it hover?

6.[2p] Resistive loss in the wiring grows with the square of the current, which is why the main battery leads are the thickest wires on the craft.

7.[2p] A low-ESR capacitor is often fitted across the battery input because it

1.[1p]
A 6S lithium pack is fully charged. With each cell at 4.2 V, what is the pack voltage, in volts?

2.[2p]
A 1300 mAh pack is rated at 100C. What is its maximum safe discharge current, in amps?

3.[2p]
The main reason to build a craft at a higher cell count, such as 6S instead of 4S, is that

4.[2p]
Voltage sag under heavy load happens because

5.[3p]
A quadcopter hovers at 9 A on a 5000 mAh pack. Using 80 per cent of the capacity as usable, roughly how many minutes can it hover?

6.[2p]
Resistive loss in the wiring grows with the square of the current, which is why the main battery leads are the thickest wires on the craft.

7.[2p]
A low-ESR capacitor is often fitted across the battery input because it