Parasitic battery drain? (TOP 5 Tips)

Parasitic drain on your battery is essentially when your car’s electrical system continues to pull energy from the battery, even when the vehicle is entirely turned off. Instead, this is when everything is off, and electricity continues to drain from the battery. To some extent, this is normal.

How do you check for a parasitic battery drain?

Pull the negative off the battery. Put the test light between the post and the ground wire. If the light illuminates, you have a draw. Use the fuse pull method to find the draw; when the light goes out, you found the draw.

What causes parasitic drain on car battery?

The most common causes of parasitic drain are under hood lights, trunk lights, headlights or glove box lights that do not turn off when the door is closed. Relay switches that are stuck in the “on” position can also cause a battery to drain.

Can a parasitic drain ruin a battery?

If a battery goes long periods without being recharged by the alternator, those tiny milliamps drawn by parasitic devices will kill it. Even normal parasitic drain, also known as “key-off drain,” puts wear and tear on a battery. Allowing a battery to go dead for long periods of time will cause sulfation.

Why does my car battery died after sitting for a few days?

Some of the most common reasons for a car battery to die repeatedly include loose or corroded battery connections, persistent electrical drains, charging problems, constantly demanding more power than the alternator can provide, and even extreme weather.

How many amps is considered a parasitic draw?

Parasitic Battery Draw A normal amount of parasitic draw for newer cars is between 50-milliamp to 85-milliamp current draw. A normal amount of parasitic draw for older cars is a reading less than 50-milliamp. Anything past these amounts indicates an electrical issue and should be addressed by a mechanic.

Can a bad alternator cause a parasitic draw?

But a battery-power drain can also be the work of a bad alternator diode or even a faulty battery. Depending on the amount of current being drained, a parasitic draw will suck all the juice from your battery in a few hours or minutes. The bad alternator diode test. The car battery hydrometer test.

Can a bad ground cause a battery drain?

A bad ground might not cause a battery to drain, but it will prevent it from properly recharging.

How do you stop a car battery from draining when not in use?

If so, here are some things you can do to save your car battery when it’s not in use.

  1. 1) Use a trickle charger or battery conditioner.
  2. 2) Avoid turning your car on and then off again.
  3. 3) Avoid short journeys.
  4. 4) Drive your car for 15-20 minutes at a time.
  5. 5) Alternate trips if your household has more than one vehicle.

Can a starter cause parasitic drain?

Once a car starts the starter does not use any battery power, the same for when the engine is switched off, the starter is always connected to the battery but it only gets triggered when the ignition switch is turned to the start position, the starter solenoid (part of the starter and bolted onto the starter) can

Can a blown fuse drain car battery?

a fuse blows to keep current from going through the circuit. in other words, there’s no way a blown fuse can drain the battery. take the battery in to get checked, it might just be a bad battery.

Will a car battery recharge itself?

Vehicle batteries do not recharge themselves, the alternator recharges the battery. The frequent use of a battery causes it to discharge whilst it is in use but when we drive our cars, the alternator recharges the battery and compensates for the power lost during the discharge.

How long should you leave a car running to charge the battery?

Be sure to drive your car for about 30 minutes before stopping again so the battery can continue to charge. Otherwise, you might need another jump start.

How to Diagnose Parasitic Drain on Your Car Battery

Are you dealing with a battery issue right now? You recently acquired a brand new battery that was in wonderful condition, but it died after only a few months. While your first inclination may be to call the customer service line of the battery’s maker and make advantage of the manufacturer’s warranty, there may be another reason for the problem. Repeated battery failure is frequently the sole indication that your vehicle is suffering from parasitic drain. What is parasitic drain, on the other hand, exactly?

Also, how do you know whether you have it before you go out and buy a bunch of batteries after that?

What is Parasitic Drain?

It is simply when your car’s electrical system continues to draw energy from your battery even after the vehicle has been completely shut off that you have parasitic drain on your battery. Unlike the situation that occurs when you forget to turn off your headlights or close the door completely and the light remains on all night, this is not the case. Instead, this is the time when everything is turned off and the battery continues to drain power from it. This is, to a certain extent, expected.

When the quantity of power drawn exceeds the typical range, it becomes an issue that may have an impact on the performance and service life of your battery.

How to Diagnose Parasitic Drain

You will need to use a multimeter in order to diagnose this problem. The way it works is as follows: To begin, ensure that your car is switched off and that your keys are not in the ignition. Change the mode of the multimeter to DC Amps and increase the amp level to the maximum. This will prevent the gadget from being damaged. Then, disconnect the negative battery wire from the battery connector on your vehicle. It should be a dark color. Take care not to allow the wire to come into contact with anything that is grounded.

  • It is important to conduct this level with the battery terminal, but to keep the multimeter to the side.
  • If there is no reading shown, gradually lower the setting until one is displayed.
  • When it comes to older autos, a value below 50 mA is desirable.
  • There might be a problem with one of the circuits that power the accessories in your automobile, such as the lights, radio, speakers, or another device.
  • What should you do if your parasitic drain is within the usual range of results?
  • You should still take efforts to ensure that your car’s battery is properly cared for.

By driving your car on a regular basis and doing longer trips on occasion, you can give it the best chance of becoming completely charged. Do you require a new car battery? Come to Powertron for high-quality batteries that will last a long time!

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You walk out to your car/truck, turn the key in the ignition, and the beautiful click-click sounds greets you. You had a battery depletion overnight, despite the fact that you did not keep the lights on. The battery cables have gone missing, and you haven’t recharged your jump-box since your previous camping trip. We’ve all been there, believe it or not. We’ll show you a straightforward method for identifying a parasitic battery drain; in other words, we’ll figure out what caused your dead battery to fail.

Pay Close Attention to Wire Leads Equipment Required:

  1. We utilized the Southwire 14090T multimeter, which had an ampere (direct current) measurement of at least 10 Amps. 8mm, 10mm, 7/16′′, or 1/2′′ Wrench/Socket – to remove your battery terminal
  2. 8mm, 10mm, 7/16′′, or 1/2′′ Wrench/Socket – to remove your battery terminal A pair of needle-nose pliers or a fuse puller — to be used for removing fuses from the fuse panel or panels
  3. Zip ties or tiny clamps to hold things together

What is a Parasitic Battery Drain?

It does not entail the introduction of parasites into your batteries, which is a positive development. There is no requirement for HazMat suits at this time. A parasitic battery drain is simply something that drains your battery on a steady and continuous basis. If you have an electrical problem, it might be a bad relay, a malfunctioning headlight/dome light switch, an alternator, or anything else that has to do with electricity. Taking your automobile to a repair because of a “unknown” problem can also be quite expensive.

How To Diagnose the Battery Drain

The problem with your battery depletion should be identified within a few minutes of your investigation. The addition of an extra person may be beneficial to this project, but it is not required. Also keep in mind that, depending on your car, you may have more than one fuse panel to contend with. The majority of automobiles include at least one fuse panel beneath the hood, as well as one within the passenger compartment. Some foreign automobiles have many fuse panels throughout the vehicle, located in various locations.

Disconnect the Negative Cable

Step 1: Remove Negative Battery Cable

The negative cable has been removed. Remove the negative battery cable from the battery post by using the proper wrench or socket to accomplish this. Given that we were working on a 2000 Ford Explorer, the battery connector was secured with an 8mm bolt in our situation. When doing this test/diagnostic, you can use either the positive or negative cable; however, utilizing the negative cable is considerably safer than using the positive. A negative wire being grounded is not a concern; but, grounding the positive wire might cause electrical equipment, including your multimeter, to malfunction.

Step 2: Check the Draw Across the Negative Cable and Battery Post

Turn on your multimeter and make sure the Amps (A) setting is set to Direct Current (DC) (Direct Current). You should be able to see a sign that looks like a solid line with dashes beneath it. You don’t want air conditioning (a/c), and this is for the electricity in your home. You will most likely have the choice of choosing between Amps or mA (milliamps), so start with Amps, ideally 10A or 20A, as a starting point. Check that your wire leads are in the right position on the multimeter before proceeding.

  • In order to measure battery depletion or current draw, you’ll need to connect your multimeter in series with the battery.
  • a.
  • Check to confirm that your leads and dials are in the right positions before proceeding.
  • The amount of Amps that are actively causing your battery to deplete should be displayed on the digital multimeter screen.

Tip: During typical operation, a vehicle will consume around 50 milliamps of current from the battery. Another Outstanding Video: Drill Bits of the Highest Quality Our Favorite Drill Bits on Video

Step 3: Remove and Replace Fuses

Start with the fuse panel located beneath the hood. While you are pulling fuses, be sure that you can see your multimeter well. Remove and replace fuses with your needle-nose pliers or a fuse remover until the Amps on the multimeter start to decline again. It is important to ensure that each fuse is returned to its proper place. Fuses should be removed. As soon as you’ve finished with the underhood fuses, you may go on to the inside fuse panels. This is where having an additional person might be beneficial; they can keep an eye on the multimeter while you are pulling fuses.

Step 4: Isolate and Fix the Issue

The problem might be resolved once you have removed the faulty fuse from the circuit. Specifically, in our situation, it was the Alternator/Voltage Regulator that was continuously drawing more than 4 Amps and it was discovered that this was due to a bad alternator. When we removed the 30A fuse, the current draw reduced to 0.2 Amps, which is still more than the industry standard. We also discovered a secondary draw with the relay/switch for the inside lighting. Taking both fuses off of the circuit reduced our Amp draw to nearly nothing.

Step 5: Replace Negative Battery Cable

As soon as you’ve identified and resolved the problem(s), you may remove the zip ties or clamps from the multimeter leads and replace the negative battery cable. You should be fine to go at this point, and the parasitic battery drain has been resolved.

How to Find a Parasitic Battery Drain

Documentation Download Documentation Download Documentation It’s possible that you have a parasitic battery drain if your car is draining electricity from the battery even when all of the lights and other electrical components are turned off (or draw). Fortunately, you can typically determine the source of a parasitic draw on your own. First, connect the negative battery terminal of your car to a digital multimeter to check the voltage. After that, remove the fuses one at a time while keeping an eye on the multimeter’s reading for any changes.

  1. 1 Make sure that all of your gadgets are unplugged from your car and that no electrical components are turned on. Close your glovebox and illuminated mirror covers after turning off the radio, heating or air conditioning, lights, windshield wipers, and other accessories. To begin, apply the emergency brake and switch off your car. If you haven’t done so before, take the key out of the ignition. Afterwards, close all of the doors, as well as the trunk or back hatch, to ensure that none of the circuits is engaged.
  • Remove any wires that may have been plugged into your car, such as a GPS device or a phone charger
  • This includes the battery.
  • Consider the following: In certain situations, you may be required to enter a security code when you first start your car after removing the battery
  • Thus, check your owner’s handbook for the code before you begin
  • 2 Charge your battery to its maximum capacity. In order to effectively identify parasitic drain, you must start with a fully charged battery and work your way down. Open the hood and look for the battery in your car. Charge the battery to 100 percent capacity with a car battery charger
  • And
  • Many automobile batteries have a voltage of 12.6 volts. It is possible to check the power with a multimeter to confirm that the battery is completely charged
  • If your battery is old or damaged, or if it does not measure 12.6 volts when completely charged, you may want to consider replacing it before continuing.
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  • s3 The negative battery wire should be disconnected from the negative battery connector. Locate the negative cable, which will be denoted by a minus sign (-) and may be covered with a black plastic cover for protection. Disconnect the negative cable from the terminal by removing the cover, if applicable, and using a wrench to unbolt it from the terminal.
  • Make careful you test for the draw with the negative wire rather than the positive cable to avoid electrical shorts. To remove the cable, you’ll most likely require an open-ended wrench with a 10-mm diameter
  • However, this is not always the case.
  • You avoid electrical shorts, make sure to test for the draw with the negative cable rather than the positive cable. To remove the cable, you’ll most likely require an open-ended wrench with a 10-mm opening.
  • Select a digital meter that can read currents up to 20 amps and voltages as low as 200 milliamps.
  • 5 Connect the negative battery cable and terminal of the multimeter to the battery. Insert the red lead into the metal circle at the end of the negative battery cable’s negative terminal. Connect the black lead to the negative battery terminal with your fingers.
  • Plastic clamps may be used to hold the leads in place, allowing your hands to remain free while the meter continues to function.
  1. 6Keep in mind that if the measurement is greater than 50 milliamps, you have a parasitic pull. It is common to get a value between 20 and 50 milliamps in a car because there are a few devices that use electricity all of the time, such as the clock on the radio. A measurement higher than that indicates a draw, which indicates that something is consuming an excessive amount of power. Advertisement
  1. 1 Pull out the fuses one at a time, keeping an eye on the multimeter reading as you do so. Under the hood, you’ll find the fuse box. Remove the fuses using a fuse puller, starting with the ones with the least amp ratings and progressing to the ones with the highest amp ratings as you go. Pulling a fuse and checking the multimeter to see whether the reading changes is recommended. Otherwise, replace the fuse and go to the next step.
  • Once you’ve gone through all of the fuses in the fuse box under the hood, you should check the fuses in the fuse box(es) beneath the dash as a last resort. The ideal way to go about this is to enlist the assistance of a friend so that one person can pull fuses while the other person monitors the reading on the multimeter. You may even prop the meter against the windscreen so that you can read it from inside the vehicle if you don’t have someone to assist you.
  • As soon as you’ve checked all of the fuses in the fuse box under the hood, move on to the fuse box(es) beneath the dash and repeat the process. With a friend, it’s easiest to do this since one person can pull the fuses while the other observes what’s happening with the multimeter’s reading. You may even place the meter against the windscreen so that you can read it from inside the vehicle if you don’t have someone to help you.
  • Typically, you may get digital versions of the handbook and wiring schematics on the internet
  • However, this is not always the case.
  • 4 Examine each device or component that is connected to that circuit. Replace the fuse and turn off each lamp, heater, or electrical equipment one at a time until the fuse has been replaced. Also, make sure that all of the switches that correspond to the components are turned on. Keep an eye out for the reading on the multimeter to decline in order to determine which component is causing the drain.
  • As an example, suppose the faulty fuse is in charge of both the power antenna and the radio system. Remove the radio from the outlet and observe if the pull disappears. If it doesn’t, unhook the antenna and wait for the reading on the multimeter to drop
  • If it doesn’t, repeat the process.
  • 5 Replace the component that is generating the draw, then detach and reconnect the multimeter and battery. The repair method may vary greatly depending on the nature of the problem, so if you’re not sure how to fix the component, you should engage a trained technician to complete the repair or replacement for you. If you are able to do the repair yourself, be sure the reading on the multimeter is less than 50 milliamps before moving on. Disconnect the multimeter and then reconnect the battery cable after you’re finished
  • 5) Replace or repair the component that is producing the draw, and then detach and reconnect the battery. Depending on the nature of the problem, the repair or replacement process will differ significantly. If you are unsure how to repair or replace a component, consult with a qualified technician. If you are able to do the repair yourself, be sure the reading on the multimeter is less than 50 milliamps before moving further with it. Disconnect the multimeter and then reconnect the battery cable after you’re finished
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Create a new question

  • Question When it comes to connecting the ammeter, why is it linked between the negative terminal and cable rather than the positive side? The ammeter may be attached to either terminal and provide equal results, with one exception: if you come into contact with a metal item when using the positive terminal, there is the possibility of a short circuit and a shower of sparks. Use the negative terminal since it is more secure
  • Question It is possible for the battery to be drained if an improperly installed new sound system is installed. If it was linked directly to the battery rather than to the ignition, the answer is yes. When the ignition is turned off, it should only use a tiny amount of power for the clock. There is something wrong with your vehicle if you can use the radio when the ignition is turned off. Question Is it true that a car alarm will deplete the battery? Yes, it is possible. The alarm should be the first thing to be unplugged while looking for a leak in order to determine if the drain is blocked
  • Question Despite the fact that I’ve removed every fuse from my BMW’s fuse box, there’s still something draining my battery completely overnight. If I remove the negative terminal from the battery and leave it disconnected overnight, the battery will retain its charge. Are you certain you checked each and every fuse? The majority of automobiles (particularly foreign and premium vehicles) are equipped with numerous fuse boxes. For further information, refer to your owner’s handbook. For example, a 2004 Saab features a fuse box in the engine compartment as well as under the dashboard in the interior of the vehicle. Question Is it correct to assume that attaching the negative terminal and generating sparks indicates that I have a draw? No. When the battery is connected, your automobile computer, as well as other components, will come to life and operate. They then go to sleep after a short period of time, much like they do when you switch off the ignition of the vehicle. It is usual to see a little spark on the connection
  • Question I own a 1979 Mercury Cougar XR7 convertible. I’m dealing with a parasitic drain and don’t have access to a multimeter. To check if there was a short, I utilized a test light. I attempted the fuse pull approach, but it failed miserably. Do you have any recommendations? Remove the negative terminal from the battery. Place the test light in the gap between the post and the earth wire. If the light comes on, you’ve got a winner. To locate the draw, employ the fuse pull method
  • When the light goes out, you have located the draw
  • And Question I have a 2008 Ford Ranger, and I just replaced the battery in it a week ago. It functioned perfectly for about a day before the battery died once more. The battery meter was set to DC auto when I took out the multimeter (field piece). The result was 12.44. It’s still not going to start! I jump-started it with another vehicle, and it started straight away. Do you have any thoughts what the problem is? I’d recommend inspecting the ground wire on your battery to see if it’s damaged. It is sufficient, and when the other car is connected by jump leads, the other vehicle is responsible for completing the circuit. Question Is it feasible that a severely worn ignition key, for example, if the key can be withdrawn without moving it to the lock position, might cause a battery drain? Yes, it is possible. There may still be certain points inside the ignition lock housing that are shutting the circuit, which will result in current flowing and the battery being drained
  • Question My vehicle is a Toyota minivan equipped with a Bruno scooter lift. The battery dies if I don’t use the car for a while. So far, the dealer has installed four new batteries. When I raise the automobile and pull the fuse, the car starts right up. What options do I have in this situation? Install a switch between the circuits to entirely shut out the electricity. Then, whenever you require the use of the vehicle, simply turn on the switch. Aside from that, make sure your motor is drawing a consistent current. Question Is it possible for Onstar to deplete your battery? Because the system is continually searching for a signal in older vehicles that are still using analog Onstar, the battery will be depleted quickly. Onstar no longer provides an analog signal and only provides a digital feed

Question As opposed to the positive terminal, why does the ammeter have a connection to the negative terminal of the cable? It is possible to connect the ammeter to either terminal with equal results, with one exception: if you come into contact with a metal item when using a positive terminal, there is the possibility for a short circuit and a shower of sparks to occur. Utilize the negative terminal; it is more secure this way; Question Is it possible that a new radio system would drain the battery if it is not setup properly?

  1. Even when the ignition is turned off, the clock should only consume a tiny amount of electricity.
  2. Question How much does a vehicle alarm deplete a battery’s energy supply?
  3. The alarm should be the first item to be unplugged while looking for a leak in order to see if the drain is blocked; Something is draining my battery completely over night despite the fact that I’ve removed every fuse from the BMW’s fuse box!
  4. Ensure that each fuse has been tested.
  5. For further information, consult your owner’s handbook.
  6. Question Is it possible to have a draw if I attach the negative terminal and obtain sparks?
  7. When the battery is connected, your automobile computer, as well as other components, will come to life.

It is typical for a little spark to appear on the connection.

Unfortunately, I don’t have a multimeter, so I’m stuck with this.

Despite my best efforts, the fuse pull approach proved to be a dud.

The negative terminal on the battery should be disconnected.

If the light turns on, you’ve got a winner.

Question It’s been a week since I replaced the battery in my 2008 Ford Ranger.

The battery meter was set to DC auto when I took out the multimeter (field piece).

Unfortunately, it is still not starting.

What do you think the issue is?

It is sufficient, and when the other vehicle is connected by jump leads, the other vehicle is responsible for completing the circuit; Question If a poorly worn ignition key can be removed without the key being turned to the lock position, is it feasible that this may cause a battery drain?

In some cases, the circuit may still be closed by points inside the ignition lock casing; this will result in current flowing and a depletion of the battery.

In the event that I don’t drive, the battery will run out.

Using the lift, I can easily remove the fuse and the car continues to operate normally.

Install a switch between the circuits to entirely shut out the electricity.

Otherwise, check your motor for a steady draw; it may need to be replaced.

As a result of the system’s persistent search for a signal in older vehicles running analog Onstar, the battery will be depleted.

In addition, Onstar no longer provides an analog signal, but only a digital one.


  • Don’t forget to look inside the cigarette lighter and power outlets as well as the outside. A parasitic draw can occur if a phone charger is left plugged in for an extended period of time. Additionally, coins can occasionally fall into the sockets and produce shorts
  • A fair rule of thumb for the maximum permissible parasitic draw is 50 milliamps. Anything greater than 50 milliamps would necessitate additional research into the specific gadget that is consuming the electricity.


  • In order to avoid electrical shorts, connect the multimeter to the negative battery terminal rather than the positive battery terminal. When working on the electrical system of your vehicle, proceed with caution. Goggles and gloves are recommended for eye and skin protection. Consider hiring an expert to complete this task. It is possible to cause harm to your vehicle’s electrical system by mistakenly disconnecting and reconnecting your battery, or it is possible that the module will reset, causing the drain to cease for a short period of time. The material contained in this page is meant to give broad answers to commonly asked concerns about this issue, and it may not be appropriate to all automobiles or all situations. Details regarding maintenance intervals and other vehicle characteristics may be found in the owner’s handbook for your particular vehicle if you have one. For any repair work that you are dubious of your ability to complete, we recommend that you hire a professional automotive mechanic to complete the necessary work


Things You’ll Need

  • Goggles and gloves for protection
  • Battery charger
  • Wrench
  • Plastic clamps
  • Digital multimeter
  • Fuse puller
  • Scrap piece of wood The owner’s handbook

About This Article

To locate a parasitic battery drain, first switch off all of the vehicle’s electrical components, then apply the emergency brake, and then remove the key from the ignition. Article SummaryX After that, charge the battery to 100 percent with a car battery charger if necessary. Then, using a wrench, remove the negative cable from the battery terminal and connect a digital multimeter to the negative battery cable and the battery terminal. Once the multimeter is connected, locate the fuse box under the hood and use a fuse puller to remove the fuses one at a time from the circuit breaker box.

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Replacing the fuse and on to the next one if the voltage does not change or lowers to a few milliamps only.

Continue reading for advice on how to solve the problem once you’ve identified the parasitic pull.

The writers of this page have together authored a page that has been read 1,789,205 times.

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One morning, you go out to your vehicle only to discover that it will not begin to run. When you check it out, you discover that the battery is dead. What the hell is going on? How did it lose charge overnight when it was turned off when it was driving perfectly just last night? Unfortunately, you may be suffering from a sluggish battery depletion in some part of your system. The next sections explain why this occurs and how to prevent it from occurring in the future. The Vehicle System includes the following components: Ignition, Charging, and Electrical Systems Intermediate level of ability This is a project that will require some expertise.

  1. What Causes the Battery to Drain Overnight Parasitic power loss is the term used to describe a sluggish battery depletion that occurs while everything is turned off. A glovebox light, an amplifier, or any other electrical component that is drawing power from the battery when it shouldn’t is referred to as a “discharge.” Because the alternator isn’t generating vehicle electricity, the malfunctioning component draws power from the battery, slowly emptying it over time until your car won’t start the following morning. This may sound similar to some Ford F-150 customers who had vehicles from 2004 to 2008, since that generation experienced parasitic battery drain issues caused by a malfunctioning park sensor that prevented the body control module from turning off interior components. Inconvenient and irritating slow power drains shorten the battery’s life and make it more difficult to use the device. After receiving a jump start or charging your battery, the first step is to test your battery or contact your local auto parts store for a free battery testing service. The batteries in your vehicle should be replaced every few years as part of your routine maintenance. It’s possible that your battery is nearing the end of its useful life and that it should be recycled and replaced with a new one. Finding a car battery doesn’t have to be a bother anymore thanks to the skilled guidance provided by Advance Auto Parts Team Members. If the battery test reveals that it is still in good condition, it is time to investigate the possibility of a parasitic power draw. Examine the alternator when you’re beneath the hood (or in the shop with Advance Auto Parts). While a diode in the alternator fails, a closed circuit is created, which drains your battery even when the engine is not running. Short-term solutions include disconnecting your vehicle’s battery at night and keeping a portable jump starter in your vehicle if you’re too busy during the workweek and can’t get to it until you get off. It’s important to remember that you’ll lose access to features such as the radio, power seat, and other settings kept in memory, and the engine may be difficult to start owing to a lack of current fuel trims. Getting a Better Understanding of the Problem When the vehicle’s ignition is turned off, any electronic gadget that has memory settings, such as a clock or radio station presets, pulls power from the battery to operate. Because of the modest size of this drain, you can leave a contemporary vehicle parked for a week or longer and it will still start and operate well. When a car is turned off, 0.05 amps should be the typical power drain, to put things in perspective. Although a clock in a radio can consume as low as 0.01 amps, the total consumption of the interior lighting can surpass 1 amp. Although it appears to be a little quantity, a single incandescent dome light consumes enough energy to completely drain a battery in a single day. Keep in mind that the drain does not have to get your battery down to zero overnight
  2. It just has to bring it down to a level where it will not start. If the battery drains while the car is idle for three or four days, the amp draw is lower than if the battery drains while the vehicle is running all night. Finding the source of an electrical draw is accomplished through a process of elimination. Check out the simple stuff first. If the dome light or other accessory lighting is still on in a closed and locked car, check to be that the switch has not been accidentally left on. If it has, just flick the switch to off. It is also possible that new aftermarket modifications or modified equipment are to blame. If you have recently upgraded your radio system, installed a new alarm system, or added aftermarket fog lights, you should begin by taking a close check at those components. It should be noted that the multimeter described below should be capable of measuring the same amperage as the fuses, up to 20 amps, and as low as the hundredths of a percent range. It’s essential to have a repair manual for this since it will include the amps drawn by each component, how to test them, and wiring diagrams demonstrating how everything is wired together on the breaker panel
  3. Make sure your battery is completely charged before you begin. If yours is running low, charge it with a battery charger or enlist the help of a friend who has a good battery to jumpstart yours
  4. Recreate the settings that was in place when the battery was depleted overnight. In other words, turn everything off, lock the doors, and remove a key with a proximity sensor from the vehicle’s vicinity. There are fuse panels in the interior of your car that you will most likely need to reach later on, but opening the door will cause the vehicle to “wake up.” The door may be opened, and the door sensor on the door jamb can be depressed with a clamp, causing the body control module to report the door as closed. It’s safe to enter if the inside fuse panels need to be examined because the door is already open and the power is still turned off. Pro Tip Wait for the car to enter slumber mode before proceeding. When you unlock or open the door of a modern automobile (particularly one with keyless entry), the vehicle is pre-loaded with driving information. That motion serves as a signal to the computer to take power in order to run the PCM, fuel pump, and accessories, resulting in a significant power demand. As an alternative, let the car to wait for at least 10 minutes following step two so that it can enter sleep mode
  5. On the amperage side of the multimeter dial, set the value to 20 amps. Disconnect the negative battery cable and turn the multimeter dial to the 20 amp setting on the amperage side of the dial. Remove the negative battery cable from the battery
  6. Attach a lead to the negative battery cable terminal. Make contact with the other lead and the negative battery post, complete the circuit in the multimeter, which will display the amp draw
  7. The power draw should be less than 50 milliamps. This will be shown as 0.05 amps on the display. If it is greater, it indicates that you have a parasitic power draw. If your current draw is less than 50 milliamps, you’ll need to go battery shopping. Please keep in mind that older vehicles may generally have a lower power draw. Pro Tip It is important to remember that there should always be some amperage. A sum of 0 readings on all of the measurements indicates that the meter is not operating properly. Use plastic clamps to keep the lines in place if you’re doing it alone, or have an assistance hold them in place while you open the nearest fuse panel. Remove questionable fuses one at a time with the fuse puller, commencing with any aftermarket electrical equipment that may have been installed. The majority of automobiles feature more than one fuse panel. This fuse is placed under the dash on the driver’s side of a Toyota Corolla
  8. After removing each fuse, check the multimeter display to see whether the amps decrease. In this case, the parasitic draw is placed in the fuse that decreases the amps. A repair manual’s wiring diagrams will show you everything that is connected to that particular fuse. Fuse panels often have covers that must be removed in order to be serviced. Find a labeled schematic on the inside of the lid that identifies the fuse and inspect each component on that fuse
  9. Replace the fuse as necessary. If a wiring diagram shows that the stereo, amplifier, and instrument cluster are all connected to the same fuse, it is possible that the failed component has defective ground, power connection, or wiring. Withdrawing power from the component will reveal where the power drain decreases to. Additionally, if the item includes a remote switch, such as a rear window defrost button, make sure the switch is working properly. Components that have failed should be replaced with new ones. When dealing with pricey equipment such as an aftermarket head unit, it is best to first unplug, examine the wiring, and then reconnect with firm connections. If it continues to drain power even when the ignition is turned off, the component has a problem and should be replaced.

The most recent update was made on October 5, 2021.

Blog – Parasitic Battery Drain

The ignition switch on most vehicles has four positions: (1) Lock/Off, (2) Acc/Accessory, (3) On/Run, and (4) Start, with the first being the most common. When the automobile is turned “OFF,” the ignition switch cuts electricity to the engine, but the connection between the car battery and the engine is not severed. How does the battery of a vehicle behave after the vehicle has been stopped or switched off. The car battery continues to be drawn from even when the vehicle is not in use, as current is required to power electronics and car accessories such as the internal clock, engine computer (for starting the vehicle), radio (for sounding the alarm), lights, mirrors, electronic seats, 12V outlets, and so on.

This is known as parasitic draw, and it is typical for a small amount of current to be drawn from the car battery when the vehicle is turned off.

Parasitic Battery Draw

For contemporary autos, a typical level of parasitic current draw is between 50 milliamps and 85 milliamps in current draw. For older autos, a measurement of less than 50 milliamps is considered to be a typical level of parasitic draw. Anything over and above these levels suggests an electrical problem that should be treated by a professional mechanic. If a car battery is not properly maintained, even if an 85-milliamp drain is considered standard for current automobiles, this quantity can nevertheless have a severe effect on the life and performance of the battery.

When the voltage falls below 12.4 Volts, sulfation begins to take place, which results in battery deterioration.

To begin, you’ll need to figure out how much parasitic draw your car generates. This may be accomplished by doing a parasitic draw test with a multimeter and checking for current (DC Amps).

Safety Precautions Before Testing

Because you will be dealing directly with the automobile battery when doing an aparasitic draw test, it is critical that you follow all safety precautions to avoid injury or damage. It is essential to remove any jewelry and to put on insulated gloves and protective eyewear to avoid being shocked or exposed to the battery while working. Make sure you are not leaning directly over the car battery, that you are not working near fires or ignition sources, and that you are working in a well-ventilated location.

Switch the Multimeter to DC Amps

It is critical to follow basic safety procedures when doing an aparasitic draw test since you will be dealing directly with the car battery, which might result in serious injury. Avoiding shock or exposure to the battery is best accomplished by taking off all jewelry and using insulated gloves and protective eyewear. Make sure you are not leaning directly over the car battery, that you are not working near fires or ignition sources, and that you are working in a well-ventilated environment. Specific instructions and safety considerations may be found in the vehicle’s owner handbook.

Disconnect the Battery Lead From the Terminal

To begin, turn off the vehicle and remove the negative (-) car battery lead from the negative (-) car battery connector; this is the black cable. Do not allow the automobile battery wire to come into contact with anything that is grounded after it has been unplugged.

Connect Multimeter Probes to the Battery Positions

Check to see that all of the car’s accessories and lights are turned off before removing the key from the ignition and unplugging any gadgets that may have been plugged into the cigarette lighter socket. It is possible that you will have to wait up to 30 minutes for the vehicle’s computer components to shut down. Once the vehicle has been turned off, put the multimeter probes in series with the car battery terminal and the car battery lead to test the battery. This will indicate the parasitic drain in Amps; if the multimeter does not display a reading, it is because the setting on the multimeter is set to a high value.

Make use of the chart below to decide if the present draw is appropriate or whether it is excessive.

In Conclusion

If the parasitic battery draw is excessive, this indicates that something is sucking an excessive amount of power from the automobile battery while the vehicle is not in use. Due to the fact that the vehicle battery continues to drain without the alternator recharging it, high parasitic draw is a concern. This might cause the battery to become flat, leaving you with a car that won’t start. It is critical to address any electrical faults that are producing excessive parasitic drain in order to avert the possibility of a dead battery.

  • Finding the primary culprit can be accomplished by removing fuses one at a time to determine which circuit is generating the excessive drain.
  • Second, it is critical to correctly maintain the automobile battery in order to keep it from running flat completely.
  • When a battery is completely depleted, the automobile will not start unless the battery is recharged or jumped to restore power.
  • Surface charging actually reduces the capacity of the battery over time.

This will help to guarantee that the battery’s charge is maintained when you are away from home. Finally, good battery maintenance will allow you to get the most out of both your automobile and your battery by extending their life.

Parasitic Battery Drains

Written by Dave Hobbs. Para What? Unbelievable how many IATN threads I come across with skilled technicians suffering with parasitic battery draining. It’s a shame. What is the limit of what is too much? What is the best way to test? I suppose I shouldn’t be surprised. When I was younger, my family owned and operated an auto electric business, and this type of work was our bread and butter. There are a lot of moving parts, and it might be perplexing for the rest of the businesses out there who have to be specialists in everything from the turn signals to the transmission.

  1. In summary, and in automotive words, a parasitic drain is an electrical load that pulls electricity from the battery when the ignition is switched off or while the vehicle is not in use.
  2. For example, we have numerous electronic gadgets, often “affectionately” known as F.R.E.D.s (Frustrating Ridiculous Electronic Devices), that are constantly linked to hot battery power circuits that are ebbing away in minute quantities from the battery’s capacity.
  3. (Maintain Alive Memory) Whether it’s the clock in the radio or the last known location of the memory mirrors, these minute quantities of KAM generated current will normally sum up to no more than 20 or 30 milliamps at the most, depending on the application.
  4. Providing the car is driven frequently in order to allow the alternator to recharge the battery, there should be no issues with the battery.
  5. If you ask me, it’s not a bad idea!
  6. It all comes down to the amount of parasitic drain that occurs, the battery’s reserve capacity (measured in minutes), and the period of time that the car is left parked.
  7. The battery will reach a point where it will no longer be able to supply power to the starter at some point between full charge and complete depletion.
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To put it another way, reducing the available AH by 20 to 30 AH for a standard battery in a storage position will result in a no-start situation for that battery.

Despite the fact that the maximum rule of thumb recommended parasitic drain is about 30 mA (0.030 amps), a typical drain generally falls between the 7-12 mA region, despite the fact that certain luxury automobiles do reach or exceed the maximum.

The quantity of AH consumed by the parasitic drain is the outcome of this calculation.

Here’s an illustration: A vehicle with a 30 mA drain and a fully charged 70 RC battery will run for three weeks on a single battery charge.

The temperature of the car at the time of the attempted start is the most crucial factor to consider.

When the temperature drops below 0°C (32°F), the battery’s starting power will be reduced to around 85 percent of its regular capacity, and the engine may require as much as 165 percent of its typical starting power to get up and running properly.

At 0°C (32°F), the battery’s capacity is reduced by half compared to its capacity at 25°C (77°F).

Now, in the other way, summer days with temperatures of 25°C (77°F) or higher enhance the battery’s self-discharge.

When operating at temperatures below the moderate range, self-discharge is negligible when compared to parasitic loss in the system.

How much of a parasitic drain on the battery should be expected from each module? However, while the accompanying table is by no means a definitive set of requirements for passing or failing “FREDs,” it does provide reasonable estimations of the parasitic drains of various devices.

How to Test

Since my father taught me to connect a test light in series with the battery line in the 1970s, the process of checking for parasitic battery drains has evolved significantly. A big parasite drain, according to the theory then (and still applicable today), would cause the test light to glow brilliantly, whereas a little parasitic drain, according to the theory, would either not light the bulb at all or just light it very weakly. Although not precisely correct, it was successful prior to the appearance of huge numbers of FREDs on the vehicle in question.

  • In addition, leaving the glove box or trunk light turned on would activate the test bulb.
  • Obvious method (whether you have FREDs or not) to determine if these lights are actually turning off when they’re meant to be turned off.
  • The fact that it’s hot indicates that it’s been burning for more time than the fraction of a second it takes to lift the lid and touch it.
  • In order to turn off the trunk light, you may get inside the trunk and have a friend close the lid as you stand there watching the light go out.
  • Obvious cautions you to be certain that your pal holds the key and not you.
  • If we look back at the test light technique, we can see that it became ineffective when some of the newer solid state modules would remain switched on for an extended period of time and drain 300-400 mA.
  • When the 1980s rolled around, the test light parasitic test was replaced with an ammeter linked in series with the battery cable on the DVOM’s circuit board.

Problems With Meters

That examination was excellent. It’s possible that the problem was there when you connected the battery wire in series with the meter. in addition to whether you have a good fuse in the meter. and you didn’t forget to reconnect the meter to the cord when you opened the door (a 2 amp dome light attempting to complete its circuit route through a 12 amp meter fuse) or, worse yet, when you attempted to start the engine. When a starter attempts to source 200 amps through a 12-amp fuse, this is referred to as the “second scenario.” Alternatively, you could connect the meter leads into the battery cable circuit via the meter’s 10 amp ammeter circuit, and at the very least, it would be able to provide the dome light when you opened the door without issue.

Some meters do not fuse their higher current ammeter part, which is a safety feature.

Sometimes, as in the case of Fluke, the fuses for both the low current (300 mA) and high current (10 amps) parts are fused together in the same circuit. The difficulty is that the fuses are extremely costly and difficult to come by.

Solutions to Meter Problems

Here’s what you need to do to fix everything. Simply connect an inline fuse in series with the leads of your meter and you’re done. When testing for low current parasitic drains, use a fuse that is slightly smaller than your meter’s low end rating (200 mA), and another inline fuse that is dedicated to putting in series with your meter’s leads when it is in the high current setting (8 amps). This way, if you make a mistake and open the door or crank the motor, you only have to replace an automotive fuse and not an exotic and expensive Fluke fuse or a very expensive meter!

Naturally, a low current inductive amp probe can be used as an alternative.

When measuring currents as low as 10 mA, which would be a realistic typical parasitic current draw for some automobiles, the device must be precise enough to be reliable.

MacGyver To The Rescue!

If your probe is precise down to 100 mA, you might be a regular MacGyver and create your own current multiplier by wrapping a piece of wire around a soda can ten times, as seen in the picture. After you have completed the loop, leave about a foot or so of wire in each end of the can (to be used later) and carefully remove the can from the loop (see illustration). Tape the ends of your freshly formed coil together and attach some alligator clips to either end. Now you may connect that coil to the battery cable by placing it in a loop and connecting the two together.

The new coil may be clamped around your “accurate down to 100 mA” inductive amp probe, and you’ll have an inductive amp probe that’s “accurate down to 10 mA.”

More Test Problems…Phantom Drains

Almost every test that has been discussed up to this point (with the exception of the super low current inductive amp probe) has one significant drawback. In order to connect the meter and/or 10X multiplier, you must first detach the battery. A high resistance short circuit (chaffed insulation) that is causing the excessive battery drain, or a leaky alternator diode, or even a light bulb that is constantly on, will not cause any issues. You then connect your meter in series with the battery cable and read the reading on the meter again.

  1. Take, for example, the case where you pull fuse 17 and the meter now reads 12 mA, which appears to be a regular and acceptable parasitic current flow.
  2. It is possible that a faulty automated load leveling height sensor (for example) will attempt to keep the air suspension compressor running.
  3. The battery will most certainly drain 12 mA if you connect your meter in series with the battery line on that particular day, assuming Murphy’s law is not on your side that particular day.
  4. What is it about catching the phantom battery drain that you find so difficult to understand?
  5. Is it better for the police to give the bad people early warning that they want to serve a warrant, or is it better for them to sneak up and bash their way into the house shouting “search warrant”?
  6. You must follow in their footsteps.
  7. It may take some “convincing” to get them to keep their batteries charged.

You’ll need a strategy to capture them while they’re in the process of depleting the battery.

If you don’t want to spend the $70 dollars on one of these from the tool truck, you can simply go to your local parts or RV store and get a battery disconnect switch, which is also known as an RV knife switch in certain circles.

Driving the vehicle and operating as many accessories as possible while the high current battery disconnect button is closed will allow you to replicate the conditions that may be causing the battery loss.

At first, test the drain using the higher current part of the meter to ensure that it is not bigger than the lower rated section of the meter’s rating.

Last but not least, turn on the battery disconnect switch.

You should be aware that you did not have to detach the battery (and thereby “tip off” those cunning “FREDs”) in order to operate the ammeter.

Now look for current draw values on the meter that are significantly higher than typical, and narrow down the list of likely causes by removing fuses as previously described.

For example, one type of late-model General Motors SUVs includes an HVAC control head that may take up to 4 hours to shut down!

One option would be to yank its fuse in order to confirm that it is the sole parasitic drain on the car that is significantly bigger than normal.

Replace the fuse, attach the battery to the cable (using the disconnect switch), and then go do something else constructive for a few hours before checking the total vehicle drain later in the day.

Catching Even Sneakier “FREDs”

In rare circumstances, you may require more than just the battery disconnect switch to solve the problem. It may be necessary to keep an eye on the meter for an extended amount of time to determine whether any solid state modules have woken up and are taking excessive power. Who, on the other hand, has the leisure to watch their ammeter? With a Tech 2 scanner and a General Motors car equipped with a class 2 data bus, you have the perfect “FRED baby sitter” ready to go to work while you are earning money doing something completely different.

  • To begin, set up your phantom parasitic drain test using the battery disconnect and ammeter configuration described earlier in this section.
  • The fuse is frequently the same as the fuse for the 12 volt accessory / cigar lighter that was previously mentioned.
  • Finally, using the Tech 2 setup option, assemble the vehicle from the ground up.
  • From there, you can access the Class 2 Message Monitor, which displays a list of all the modules connected to the bus.
  • The term “Active” will be followed by an odd number such as 1, 3, 5, and so on.
  • (See illustration 6) The previous odd number (1, for example) will be incremented up to an even number (2) as each “FRED” falls asleep on the bus and stops drawing any more current than the average KAM current throughout this process.
  • You can now keep track of bus activities by looking at the status of the modules on the Tech 2.
  • Because the BCM is often the bus power mode master device, it is possible that it will be the first to wake up, followed by any other modules that may be waking up.
  • Another option is to leave the Tech 2 alone and let it to keep an eye on the bus’s condition.

This occurred because the Driver Door Module (DDM) woke up (thus increasing the status to a 3) and then went back to sleep (thus increasing the status to a 4) and then woke up yet another time (thus increasing the status to a 5) and finally went back to sleep, which resulted in the Driver Door Module (DDM) having the status of “Inactive” but at 6, which you can see on the tool.

(Remote Keyless Entry) (Remote Keyless Entry) It’s quite sly, that DDM of yours.

And the greatest part is that you can delegate the task to the Tech 2 while you focus on anything else.

Hopefully, this study of parasitic battery drain tests, as well as some recommendations that may be completely new to you, have sharpened your abilities.

AVI is giving away one million dollars worth of training, and we want you to be a part of it by participating in our free training giveaway.

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