Treeri Posted October 21, 2023 Share Posted October 21, 2023 Greetings, I am currently experiencing an issue with my W221 S500 vehicle, wherein a parasitic draw of approximately 10-11 amps has emerged. Consequently, the battery becomes fully depleted within a span of approximately three hours, despite being fully charged. Additionally, the battery only charges when disconnected from the vehicle. It is worth noting that I have recently had the handbrake actuator and air suspension pump replaced within the past 72 hours. I would greatly appreciate any suggestions or recommendations regarding this matter. Thank you. Quote Link to comment Share on other sites More sharing options...
alabbasi Posted October 21, 2023 Share Posted October 21, 2023 Could you please attempt to disconnect the circuits or remove the fuses in order to assess if the power drain persists? The current draw of 11 amps is very substantial and has the potential to result in overheating. I would be tempted to unplug the battery during periods of nocturnal inactivity or when the vehicle is left alone. Quote Link to comment Share on other sites More sharing options...
Doncaster34 Posted October 21, 2023 Share Posted October 21, 2023 The product of 11 amperes and 12 volts yields a power output of 132 watts, if the calculations are accurate. Consequently, it may be inferred that a component or system is generating a significant amount of heat. (Warmer than two headlamp bulbs on main beam) So finding it shouldn’t be too much of a problem. Is there a block heater installed in your vehicle? It is advisable to inspect the control relay for the block heater in order to ensure its proper functioning. An other, if less probable, factor that might contribute to the issue is a malfunctioning seat controller or motor. However, it is unlikely that this component would draw a current of 11 amps, and any potential odour associated with such a high current would surely be detectable. Quote Link to comment Share on other sites More sharing options...
Ken_Lion Posted October 21, 2023 Share Posted October 21, 2023 The numerical data provided does not align or correspond appropriately. If we assume that the battery capacity is around 75 Ah, it would need a much greater current of around 25A to completely discharge the battery within a time frame of 3 hours. The product of 11 amperes sustained over a period of 3 hours yields a total charge of 33 ampere-hours. As recommended, begin the process of sequentially removing fuses until the electrical drain ceases. Subsequently, this will enable identification of the specific circuit responsible for the issue, facilitating further investigation. The power output of 11A is about 140W, indicating that a component or system is likely experiencing a significant increase in temperature. The power output of 25A exceeds 300W. Quote Link to comment Share on other sites More sharing options...
Doncaster34 Posted October 21, 2023 Share Posted October 21, 2023 It is worth noting that battery capacity is often evaluated using the 20-hour rate. Therefore, a 75Ah battery that is completely charged and in optimal condition will be able to provide a continuous current of 3.75 amps for a duration of 20 hours. The indicated capacity will be significantly reduced with an increase in the load. However, it seems that the capacity is still relatively insufficient. Quote Link to comment Share on other sites More sharing options...
xsports Posted October 21, 2023 Share Posted October 21, 2023 The potential cause of the issue may be attributed to the alternator. The rapid depletion of the battery might be attributed to a malfunctioning diode or a defective regulator. Quote Link to comment Share on other sites More sharing options...
Starcar2022 Posted October 21, 2023 Share Posted October 21, 2023 Fuse testers are a cost-effective and suitable first step in the process of identifying and resolving a parasitic drain. I own this particular item. Quote Link to comment Share on other sites More sharing options...
Treeri Posted October 21, 2023 Author Share Posted October 21, 2023 I would want to express my gratitude to all individuals for their valuable recommendations. I have attempted to remove the fuses for the newly replaced components, nevertheless the power consumption persists at its original level. Consequently, I plan to begin the process of removing all other fuses tomorrow. The battery is now in a disconnected state and undergoing a trickle charging process throughout the night. When it was connected and subjected to a high-capacity charger, it was unable to surpass a voltage level of 5.5 V due to the excessive drain being experienced. Furthermore, I am unable to detect any signs of elevated temperature or detect any odours indicative of burning. Quote Link to comment Share on other sites More sharing options...
xsports Posted October 21, 2023 Share Posted October 21, 2023 Quote Link to comment Share on other sites More sharing options...
migueldosantos77 Posted October 21, 2023 Share Posted October 21, 2023 If a metre connected to the battery indicates a current drain even when all electrical components are turned off, it would be advisable to systematically remove fuses to identify the source of the drain. Alternatively, seeking assistance from a mobile auto electrician would be a viable option. It is likely that the issue is related to the recent maintenance performed on the vehicle. Quote Link to comment Share on other sites More sharing options...
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