Quick Answer: How To Perform A Parasitic Draw Test?

Parasitic Draw Test with a Multimeter

It could be anything from a dimming dome light staying awake or a glove compartment switch sticking on, to faulty alarm wiring, but a car battery may experience significant drain long after the engine has been turned off, which is known as parasitic draw and can lead to a flat.

What You’ll Need

A digital multimeter, rather than an analog one, is best for this test; you’ll need a milliamp range for higher resolution to detect minimal current draw, and it’s best to stick with a brand name, though you don’t have to go with a top-of-the-line Fluke model.


Before starting, make sure the battery is fully charged and that all doors are closed, the radio is turned off, and all accessories are disconnected. It is always best to do a parasitic draw test from the negative side to avoid accidentally shorting. Avoid starting the engine or turning on the headlights as this will likely blow a fuse in the multimeter.


When the multimeter display drops to a nominal mA draw, it’s time to look for faults. The tried-and-true method is to start pulling fuses to see which circuit is the culprit, then repair or replace the item and test again.

Parasitic Draw Test on Newer Cars

Electric mirrors, heated memory seats, GPS, trackers, and a slew of other gadgets can make parasitic draw testing with a multimeter a pain. Some of these systems are interconnected, exacerbating the problem. Even car keys indirectly cause current drain.

Old vs New Method

There’s no need to remove auto fuses or disconnect the battery because they have open test points on them. Different size fuses will show a different voltage drop; for example, a 10A fuse with 1A flowing through it might show a voltage drop of 5mV.

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Drive the car and operate all circuits (wipers, heater, seats, windows, GPS, lights, sat-nav, etc.) before returning and removing the key. Consult the manual for information on how long the various systems take to sleep.

Key to Better Battery Life

The key to a long battery life is to avoid parasitic draws and keep the battery charged above 12.4V. Vehicles that are only used occasionally are more prone to losing charge, which leads to sulfation, which compromises performance and longevity. Those that are driven daily benefit from the alternator, which keeps the battery charged.


Parasitic draw on one’s vehicle can be a nightmare, and it frequently occurs at inopportune times; however, it doesn’t have to be, and it is entirely within the realm of the layman, as long as a multimeter is available. See how to check battery charge here.

Choosing a Multimeter

For a parasitic draw test with a multimeter, all you need is a basic device that can test amperage and has an auto ranging mode. INNOVO makes decent multimeters for automotive tasks, such as the 3340 or the less expensive 3320.

How is a parasitic test performed?

Parasitic diseases such as filariasis, malaria, and babesiosis can be diagnosed by looking at a blood smear under a microscope. This test is performed by placing a drop of blood on a microscope slide, which is then stained and examined under a microscope.

How do you check for a parasitic battery drain?

Remove the negative terminal from the battery and connect the test light to the post and ground wire. If the light illuminates, you have a draw. Use the fuse pull method to locate the draw; when the light goes out, you’ve located it.

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How do I know if I have a stomach parasite?

The toxins that a parasite releases into the human bloodstream cause a variety of symptoms, including unexplained constipation, diarrhea, gas, bloating, nausea, and other Irritable Bowel Syndrome symptoms. You traveled internationally and developed diarrhea.

How do you tell if you have a parasite in your stomach?

The following are some of the most common symptoms of a parasitic infection:

  1. Stomach cramps and pain.
  2. Nausea or vomiting.
  3. Dehydration.
  4. Weight loss.
  5. Swollen lymph nodes.
  6. Digestive problems such as constipation, diarrhoea, or persistent gas.
  7. Skin issues such as rashes, eczema, hives, and itching.

Can a bad battery cause a parasitic draw?

However, a parasitic draw can be caused by a bad alternator diode or even a faulty battery, and depending on the amount of current drained, a parasitic draw can drain all of your battery’s juice in a matter of hours or minutes.

What is acceptable parasitic draw?

A normal amount of parasitic draw for newer cars is between 50 and 85 milliamps, while a reading less than 50 milliamps indicates an electrical issue that should be addressed by a mechanic. Anything above these amounts indicates an electrical issue that should be addressed by a mechanic.

What is a parasitic drain on a battery?

Parasitic Battery Drain: Causes and Solutions, according to AxleAddict, parasitic battery drain occurs when power is drained from batteries after the truck’s engine has been turned off, reducing battery life both in the short and long term. The more you charge batteries, the faster they die for good.

How do you check for a parasitic draw with a multimeter?

Steps to take

  1. Step 1: Start the test with a fully charged battery u2013 a good one should have a voltage of around 12.6V.
  2. Step 2: Disconnect the Battery.
  3. Step 3: Connect the Multimeter.
  4. Step 4: Allow the Car to Sleep.
  5. Step 5: Read the Meter.
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How many amps is considered a parasitic draw?

A parasitic draw test requires a Digital Multi-Meter (DMM) that can handle a minimum of one milliamp and up to 10 amps.

How do you check amp gauge?

Do not swap the leads from the temp gauge! Set your multimeter to OHMS, disconnect the battery ground cable, and probe the two terminals of the ammeter. If you have continuity, the gauge MAY be good; if you have no continuity, the gauge is definitely BAD.

How do you test an alternator with an amp clamp?

Test of the alternator’s amp output.

  1. Clamp the ammeter around the alternator’s positive output wire.
  2. Connect the carbon pile to the battery.
  3. Zero out the ammeter (connect as above and conduct the test with the vehicle off).
  4. Start the vehicle and maintain a speed of around 1,500 rpm.

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