Q: Dead truck battery every time it's left off for a few hours.

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My truck keeps completely dying after it's left off for a few hours, dead to the point where my key fob will not even unlock it. My battery has been tested at two different stores and they both say it's good. The first store told me I had a bad alternator and after replacing it, I'm still having the same issue. Should I replace my battery anyways and see what happens since it's still covered under warranty? Or should I get a test light and try to find a power draw coming from somewhere in the vehicle? If so, how do I actually go about doing that?

My car has 216000 miles.
My car has an automatic transmission.

If the battery is new and charging system output has been measured and is within specifications, the only reason a battery will discharge is if the car sits for a long period of time (batteries will self-discharge even if not used) or if there are parasitic (excess) loads on any of the car’s electrical circuits. If there is excess current flow that is slowly draining the battery, a Mechanic would use an ammeter to test all of the various circuits until the faulty circuit is found. Then that circuit is traced to find the fault and repair it. If you want these steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an electrical diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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