To use a multimeter, plug the black lead into the COM socket and the red lead into the voltage/ohms socket, turn the dial to the setting you need (DC volts, AC volts, resistance or continuity), then touch the two probes to the points you're testing and read the display. It's the go-to tool for checking batteries, fuses, wiring and simple faults around the home.
What is a multimeter and what can it do?
A multimeter is a handheld tester that measures several electrical properties in one device. The common jobs are checking voltage (is there power?), resistance (is a component healthy?) and continuity (is this wire or fuse broken?).
For a home DIYer it answers everyday questions fast: is that battery flat, has the fuse blown, is the extension lead broken inside? You'll find them alongside our wider Electronics range, and they pair well with a well-stocked toolbox from our Tools collection.
Getting to know the parts
Before you measure anything, get familiar with the layout. Every multimeter shares the same three basics.
- The display shows your reading and the unit (V for volts, the omega symbol for ohms).
- The rotary dial selects what you're measuring and, on manual models, the range.
- The probe sockets, usually three: COM (common, for the black lead), a volts/ohms socket, and a separate high-current socket for measuring amps.
The black probe always goes in COM. The red probe moves depending on the job, which we'll cover as we go.
Safety first: read this before you start
Testing low-voltage batteries and unplugged devices is very safe. Testing mains power is not a beginner job, so keep to the rules below.
- Never touch the metal probe tips while measuring live circuits.
- Leave mains wiring to a licensed electrician. In Australia it is illegal for unlicensed people to do fixed household electrical work.
- Start on the highest range if your meter is manual, then step down for a precise reading.
- Check your leads for cracked insulation before each use and replace them if damaged.
Stick to batteries, fuses, globes and unplugged appliances and you'll get plenty of value with no risk.
What you'll need
You don't need much to get started, just the meter, its leads and something to test.
- A multimeter with working test leads
- The batteries or component you want to check, such as Arlec AAA alkaline batteries or Duracell Coppertop AAA batteries
- Good light, so a torch like the Infinity X1 rechargeable torch helps in dim spots
- A steady surface to work on
How to test a battery (DC voltage)
This is the most common home use and the best place to learn. It confirms whether a battery still has charge.
- Plug the black lead into COM and the red lead into the V (volts/ohms) socket.
- Turn the dial to DC voltage (marked V with a straight line, or V⎓). For AA and AAA cells, select the range just above 2V, or leave an auto-ranging meter as it is.
- Touch the red probe to the positive (+) end and the black probe to the negative (−) end.
- Read the display. A healthy 1.5V alkaline cell reads around 1.5V to 1.6V. Under about 1.3V it's on the way out; under 1.2V, replace it.
Rechargeable cells read a little lower by design. A charged 1.2V NiMH cell such as the Energizer Recharge AA batteries sitting near 1.2V to 1.3V is perfectly normal, so don't mistake that for a flat battery.
How to check for continuity (broken wires and fuses)
Continuity mode tells you whether electricity can flow through something. It's how you find a broken wire, a blown fuse or a bad switch.
- Make sure the item is unplugged and switched off with no power to it.
- Set the dial to the continuity symbol (a small sound-wave icon). Keep the leads in COM and the V/ohms socket.
- Touch the two probes together first. A good meter beeps, which confirms it's working.
- Now touch one probe to each end of the wire, fuse or component. A beep means the path is intact; silence means it's broken and needs replacing.
This one trick saves buying a whole appliance when a $2 fuse is the real problem.
How to measure resistance (ohms)
Resistance mode measures how much a component resists current flow, useful for checking things like heating elements and resistors.
- With the power off, set the dial to the ohms range (the omega symbol).
- Place a probe on each end of the component.
- Read the value. A reading near zero means very low resistance (a near-perfect path), while OL or 1 on the display means the resistance is beyond the range, effectively an open circuit.
Always measure resistance on components that are disconnected from any power source, or you'll get false readings and risk damaging the meter.
Common beginner mistakes to avoid
A few simple slip-ups trip up nearly everyone at first. Knowing them in advance saves frustration and blown fuses.
- Leaving the red lead in the amps socket then measuring voltage. This can short the circuit and blow the meter's internal fuse.
- Measuring resistance on a live circuit. Always switch off and disconnect first.
- Reading DC on the AC setting (or vice versa) and getting a nonsense number. Match the setting to the source.
- Forgetting to check the meter's own battery. A flat meter gives wrong readings, so keep spare cells on hand.
When to call a professional
A multimeter is brilliant for low-voltage testing, but it doesn't make mains wiring safe to touch. Any fixed household wiring, switchboard work or fault on a powerpoint or light circuit should go to a licensed electrician.
Use your meter for batteries, torches, remote controls, fuses and unplugged gear, and leave anything connected to the mains to a professional. That way you get the convenience without the risk, and you stay on the right side of Australian electrical rules.
Frequently asked questions
How do I test a battery with a multimeter?
Set the dial to DC voltage, put the black lead in COM and the red lead in the volts socket, then touch the red probe to the positive end and black to the negative end. A healthy 1.5V alkaline cell reads about 1.5V to 1.6V. Below 1.3V it's weakening, and under 1.2V you should replace it.
What does the beep on a multimeter mean?
The beep is continuity mode. It sounds when electricity can flow between the two probes, confirming a wire, fuse or switch is intact. No beep means the path is broken. Always test with the item unplugged and powered off, and touch the probes together first to confirm the meter is working.
Can I use a multimeter to test household mains power?
You can measure at an outlet with the right AC setting, but it is not a beginner task and any fixed wiring work is illegal for unlicensed people in Australia. Stick to batteries, fuses and unplugged appliances. For anything involving switchboards, powerpoints or light circuits, call a licensed electrician.
Why does my rechargeable battery read lower than 1.5 volts?
Because rechargeable NiMH cells are 1.2V by design, not 1.5V like alkalines. A charged rechargeable AA or AAA sitting around 1.2V to 1.3V is completely normal and not flat. Only worry when the voltage drops well below that under load, which points to a cell nearing the end of its life.
