My Hyundai HB20 2023 has this annoying problem: the battery drains in about 3 days if I don't use the car. I already took it to a shop and they say it's not a faulty alternator. Could it be something electrical consuming power even when it's off?
Yeah, it could be some component with parasitic drain even with the car off - your phone charging in the outlet, the comfort module, sensors, or even a stuck relay that's draining the battery 24/7. Try disconnecting the fuses one by one while you monitor the consumption with a multimeter (put it between the negative battery terminal and ground) to identify which circuit is drawing abnormal current; normal idle consumption is usually in the tens of milliamps, anything above that signals a problem. Another common thing is an interior light or trunk light that won't turn off properly - I had that happen to a friend's car once where the lamp stayed on without realizing it because the door switch was poorly calibrated.
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