For the electrical components of the car to function properly, it is important to have the car battery working smoothly. The battery is responsible for providing voltage to the vehicle’s electrical components and any fault with the battery negatively impacts their functionality. One of the common faults with the car battery is the parasitic draw whereby the electrical system continues to draw power from the battery even when the vehicle is turned off.
In this guide, we will discuss the following points related to parasitic draw:
- Causes of a parasitic battery drain
- How to check for parasitic draw
- Normal amount of parasitic draw and parasitic draw test with multimeter
Causes of a Parasitic Draw
Common causes why the electrical system continues to draw power from the battery even when the vehicle is turned off are as follows:
- Electrical Equipment Turned On For Long: One of the most common causes of battery drain is leaving electronic equipment turned on. The lights, radio, and air conditioning require power to operate, which is obtained from the automobile battery. Leaving any of those devices turned on unnecessarily will quickly drain power from the battery.
- Battery Has Passed Its Lifespan: Most batteries have a lifespan of 2 to 3 years. After that period, they drain too rapidly and lose their ability to charge properly. Although keeping your battery in a good condition can extend its lifespan, it is recommended to replace the battery once it is past the lifespan date.
- Alternator Failure: The car alternator recharges the battery and provides power to various electrical systems such as lights, air conditioning, and power windows. Your battery may drain if the alternator has a faulty diode.
When diodes fail, the alternator’s charge output diminishes. If only one or two diodes fail, the alternator may still provide enough current to run the vehicle’s electrical components, but it may not be adequate to handle larger loads or keep the battery completely charged.
Parasitic Draw Test
If your car is draining electricity from the battery even when all of the electrical components are turned off, you have a parasitic draw on a car battery. Here’s how you can perform a parasitic draw test to diagnose a parasitic drain:
- Disconnect all of your vehicle’s devices and ensure that none of the electrical components is turned on. Switch off the radio, HVAC system and the car’s ignition system.
- Recharge your battery completely. To identify the parasitic drain, you must start the test with a fully charged battery. To confirm that the battery is completely charged, use a multimeter to check the voltage.
- Take the negative battery cable and disconnect it from the negative battery terminal. A minus symbol denotes the negative cable.
- Connect the multimeter to the negative cable and terminals of the battery.
- A normal amount of parasitic draw for cars ranges between 50-milliamp to 85-milliamps. If the amount of parasitic draw exceeds these amounts, it indicates an electrical issue and should be addressed by a mechanic.
There is no way to avoid parasitic draw as electrical components require power even when the ignition is switched off. However, you can reduce the parasitic drain by unplugging optional devices like chargers or cables when the car is parked. Moreover, it is important to test your car battery’s performance regularly so that you can detect if there is any fault in it.
This concludes our guide about the parasitic draw on a car battery. It is strongly advised to get your car battery repaired or replaced as soon as it starts showing symptoms of malfunctioning because driving with a dead car battery can cause your car’s engine to stop. If you are looking for cars with high-quality batteries, check out these used cars for sale in the UAE at reasonable rates.
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