Understanding Normal Parasitic Draw in Car Batteries
Many individuals find themselves confused by small measurements, such as that of 0.12 mA, which can be misinterpreted as extremely low. In the context of a car battery, even a 0.12 mA (0.12 milliamps) can be considered a typical value. This article aims to clarify what constitutes a normal parasitic drain in car batteries, addressing common misconceptions and laying out why .12 mA is indeed a realistic and expected value.
Why the Measure is Questionable
It is important to be precise when discussing electrical readings. The confusion often arises due to the unit of measurement used. When discussing current, it is widely accepted to refer to milliamps (mA) rather than microamps (μA), as the former is more commonly used in automotive diagnostics and specifications.
In the automotive industry, manufacturers specify typical parasitic drain values that are in the range of milliamps. A 120 milliamps drain would be considered very high and in many cases, would suggest a malfunction in the vehicle’s electrical system. Therefore, if the test result reflects a 0.12A (120 milliamps) drain, this would be more consistent with known manufacturer specifications and would not be normal for a car battery in modern vehicles.
Modern Cars and Parasitic Drain
One significant factor contributing to normal parasitic drain in modern cars is the vehicle's computer system. Modern car manufacturers integrate sophisticated computer systems to manage various functionalities, such as memory retention, parking sensors, and keyless entry systems. These systems are designed to retain state by storing data in non-volatile memory when the vehicle is turned off. However, these memory circuits require a minimal power supply to maintain their state, and this power draw can often be in the order of a few milliamps.
When the ignition is off, the car's computer retains its memory using very low current. Current values around 0.12 mA are typically within the expected range for maintaining the non-volatile memory on the computer and other control modules. This drain is necessary for ensuring that the vehicle's systems can operate correctly upon re-ignition without losing any critical data or functionality.
Implications of Excessive Parasitic Drain
The presence of 0.12A (120 milliamps) rather than 0.12 mA (0.12 milliamps) would necessitate further investigation beyond this article. A drain of this magnitude could indicate a potential issue, such as a faulty circuit or a component that is drawing too much power when the vehicle is off. Typical culprits might include faulty keyless entry systems, faulty sensors, or other components that are not designed to draw the current they do when the power is disconnected.
For instance, if a counterfeit or poorly manufactured component is installed in a vehicle, it may draw significantly more power, leading to a higher parasitic drain. In some cases, a parasitic drain that is unexpectedly high might also suggest a parasitic circuit that was not designed, leading to a false positive.
Conclusion
A 0.12 mA (0.12 milliamps) reading on a car battery is indeed within the range of normal operation for modern vehicles. This low drain is typically required to maintain non-volatile memory and keep the vehicle's systems operational without power. However, it is important to distinguish between 0.12A and 0.12 mA as the latter is the correct unit of measurement in the context of automotive diagnostics.
For troubleshooting and maintenance purposes, it is recommended to familiarize oneself with the normal operational parameters of the vehicle's parasitic drain. Regular checks and understanding of the expected values will help in identifying and resolving issues related to abnormal parasitic draw.