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Q: New battery and alternator, battery drains within 48 hrs

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Bought a new Duralast gold battery and alternator. Installed them both. Battery drains almost completely within 48 hrs. Had the alternator tested thinking it might have been defective. Alternator was good. I would like to know all possibilities as to what might be causing the issue. (why it could be happening, how to diagnose)

My car has 175500 miles.
My car has an automatic transmission.

Hi There, It sounds like you may have some kind of parasitic draw on your system, a short or potentially a bad voltage regulator. The voltage regulator is a unit that regulates the charging of the battery by the alternator. When the voltage regulator is not working properly, this may result in the alternator allowing too much power to be delivered to the battery resulting in damaging wires and prematurely sometimes destroying the battery. A common sign of this is usually the acid inside the battery boiling causing the battery to swell. You may also smell a bit of smoke due to things potentially getting too hot. In other cases it may result in the alternator not supplying enough power to the battery, resulting in undercharging the battery or not charging it at all. I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.

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