Battery Load

Project Number: 31

Description: Build the circuit and set the meter (M6) to the 5V setting. Set the slide switch (S5) to position C and read the battery (B4) voltage when it is not running anything. Now set the switch to position B and see what happens to the voltage when everything turns on. If the battery is already weak, some modules may not start. If you watch the voltage for a while, you will see it slowly drop as the battery gets discharged. If the battery was already weak, the voltage will drop faster. If you remove some of the devices the battery is running (the LEDs, motor, and hand crank, then the voltage will not drop as much when the switch is turned on.

Snappy: The battery makes electricity by using a chemical reaction, but has a limited amount of current and not all of it can react at the same time. When a battery cannot supply as much current as a circuit needs, the voltage (electrical pressure) drops. That is why the voltage drops when the switch connects the battery to the rest of this circuit. Engineers refer to all the devices a power source is running as the load, because they are the burden the power source is carrying.