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Q: My car battery is dying while it's parked. I replaced the battery and in just a week it died while sitting parked overnight.

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That's about it. Nothing else has really changed. Could something be draining the battery? I have a rear light out, would that affect anything?

My car has 128000 miles.
My car has an automatic transmission.

Hi there. There could be a parasitic load on the battery causing it to drain overnight. To check this symptom perform the following:

  • Remove the negative battery cable (-)
  • Get a digital meter and put one lead on the negative battery cable (-) and the other lead on the negative battery post (-).
  • With the key removed from the vehicle monitor what the meter reads. If there is a voltage of 2 volts or more, then there is a load on the battery.
  • With the key off, turn on everything in the vehicle one thing at a time.
  • When the meter reads zero or about 0.5 volts, then that item is causing the issue and would need fixed or replaced.

If you need further assistance with your battery drawing down overnight, then seek out a professional, such as one from Your Mechanic, to help you.

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