How to Set Up a Multimeter for Parasitic Draw

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Like any other electrical device, your car has a parasitic draw. The time has come to turn off this parasitic drain with a multimeter. In this article, we will show you how to use a multimeter to test your car’s parasitic draw. 

Klein MM700 Digital Multimeter
Klein MM700 Digital Multimeter

What exactly is parasitic draw? 

As always, for electronics to work, a circuit must be able to move a current between two points. Without this connection, the electrons have nowhere to go and the circuit will not work. The most common way to complete this circuit is with a wire, or printed circuit board. But wires can break, and it’s often easier to work with a loop that’s already there. 

This is where parasitic draw comes into play: 

Parasitic draw is when the device draws power from the battery even when it is turned off or not even connected. It also occurs when a component draws power even though it is not actually part of the circuit. When this happens, the circuit still behaves as if the wire still exists and continues to function normally. 

If enough current drains the battery, meaning even if you don’t notice the draw, you can still run out of juice! Imagine the alarm clock on your nightstand constantly draining the battery and messing up your morning routine. 

The parasitic draw of the vehicle means that more electrical energy is drawn from the battery than it is charging the battery. This can happen if there is an open or short circuit in the vehicle’s wiring. 

The main ways to measure current is to use one of the two methods below: 

  • A clamp-on ammeter is a device that clamps around the wire under test and measures the current through it. 
  • Digital multimeter with current clamp. A clamp is placed around the wire under test, allowing the multimeter to read the current. 

Parasitic draw can be tested with a multimeter to measure current in a wire through which no current is expected to flow. The multimeter is set to the ohm setting and two probes are placed on each end of the wire being tested. If the resistance is greater than zero ohms, current will flow through the wire. 

Utilizing a Multimeter to measure Parasitic Draw 

It’s a pain to figure out why your car’s electrical system drains the battery when it’s not in use, but a multimeter can be a big help. When dealing with parasitic draw, you must know that this is the current that electrical devices draw even when they are not in use. This means that even when the devices are turned off, they still use a lot of energy, which is not cost-effective. 

Here are the steps for setting up a multimeter in order to measure parasitic draw: 

  1. Prepare what you need. All you need are some common electronic components (resistors, capacitors, transistors, integrated circuits) and a multimeter, which you can buy at a reasonable price. 
  2. Make sure your multimeter is working before using it by measuring a known voltage, such as an AA battery. 
  3. Turn off the vehicle and let it stand for a few minutes. This gives the electrical system time to discharge the stored voltage. 

Use a multimeter to measure voltage between ground and all of the following: 

  • battery positive terminal (red wire) 
  • battery negative terminal (black wire) 
  • chassis ground (usually bare or green wire) 
  • if any reading is above zero, you have parasitic draw. 

The most common culprits causing parasitic draw are from accessories such as the radio and remote start. Other issues include improperly installed alarm systems. If you’re thinking it’s an accessory, consider swapping it out or ditching it altogether. If you have interference from the alarm system, see its installation instructions. 

More on Multimeters

If you build your own electronics lab from scratch, you might be surprised how quickly you can blow through a few hundred dollars—that’s why many hobbyists stick to the lab. 

But if you’re determined to build an electronics lab without breaking the bank, you don’t have to stop at basic equipment. The next device you should consider is a multimeter. 

A multimeter is a device that can measure voltage, current, resistance and inductance. Basically, it is a device that includes: display unit, control unit, power supply unit, communication unit and sensors. 

However, multimeters are also very useful tools for troubleshooting electrical circuits and devices connected to them.

The multimeter is an invaluable tool in your electronics lab because it helps you diagnose circuit problems, find out how much current a device is drawing, and test connections to make sure they aren’t shorted or open. If you are building your electronics lab on a budget, you can start with a basic multimeter. 

Why do I need to use this tool? 

When diagnosing parasitic diseases it is important to use a multimeter as it will give you a quick indication if your car has a parasitic draw. If there are parasites in your car’s electrical system, it can cause problems in your car. 

Specifically, reactive power can cause battery failure because it drains a car’s battery. With a multimeter, you can check the battery voltage and make sure it is in good condition and has no reactive power. 

Choosing the Right Tool

There are four basic types of multimeters you can buy to test reactive power in automotive circuits. The four types are analog, digital, LCR, and oscilloscopes. Each different meter has a different range of values ​​it can measure. Some can measure several different values ​​at the same time. 

All of these types are essential tools for any electrician or hobbyist. However, choosing a multimeter is fairly confusing, as there are many models, hundreds of features, and a wide range of prices. If you are purchasing a multimeter for the first time, it is a good idea to read up on all the different types and features to make sure you end up with one that suits your needs.