Q: Something is draining battery. When I turn air conditioner on, the battery level drops. So could this be the culprit.

asked by on May 30, 2017

Battery draining, really noticeable when ac in operation. Sometimes when I start car ac is on. Already replaced the instrument cluster.

My car has 136000 miles.
My car's transmission is unknown to me.

It sounds like you may have a bad alternator or voltage regulator that is not properly allowing the battery to charge or maintaining the charge. Turning on the AC puts an additional load on the entire system resulting in the deficiency in the charging system further draining the battery. 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. 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. In some cases when a battery is too weak or damaged, it may no longer hold a charge for any length of time, in which case the alternator may be doing its job, but the battery is just simply too weak to hold a charge. In either case, I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.

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