Battery life

Batteries or electrical cells are made using a range of different substances. There are zinc dry-cells, alkaline cells and lead-acid accumulators. When you use them, they become exhausted at different rates. So choosing the right type of battery for a job is very important.
In this investigation, you will measure the voltage of a cell over a period of time and until it becomes exhausted. A voltage probe connected to the computer will help you do this. Or you can connect the voltage probe to a data logger which lets you take the readings away from the computer. Either way, you should be able to measure a decreasing voltage over time and your sensing software will show this as a graph of voltage against time.

What you need

batlife.jpg (14311 bytes)

Electrical cells, lamp, switch, leads, voltage probe, data logging interface.

Setting up

Connect up the circuit as shown - disconnect the battery for the present. Connect the sensor to a socket on the interface.
Start the sensing software. Your system may be able to recognise the sensor automatically, but if not, you do yourself. If the voltage sensor has multiple ranges, use the 2V range.
Connect up the battery. Then get the software, or the data logger to record for around 48 hours. Repeat using a different type of battery.

Questions

How does the graph show the decay of the battery?
Which battery keeps a high voltage longest?
How do different batteries decay with time?
What uses would you recommend for these types of battery?
Does warming the battery help it recover?

Teacher question

As an alternative, a data logger can be used to take the readings. You set up the circuit and press a button to start the data logger recording. When the cell is exhausted, or 48 hours later, get your software to transfer data from the data logger.
What discoveries are there to be made about the choice of batteries? How do Metal Hydride batteries compare with Nickel-Cadmium batteries? Click here to respond.

This activity was adapted by Roger Frost from The IT in Science book of Data logging and Control. This page is � IT in Science. It may be reproduced only for use within your school.