Car Not Starting? It might be Parasitic Car Battery Drain

car battery drain LongmontSeveral components of modern cars are designed to draw some current when the car is off, such as radio presets, the clock and the engine computer’s internal memory. All combined these elements should not draw more than 50 milliamps and cause no issue with the vehicle’s battery. However, if you keep encountering a dead battery but the engine runs fine after it’s charged, a charging-system voltage test shows no problem with the alternator and no electrical issue can be found, then the vehicle has parasitic battery drain. The ASE-certified mechanics at Best Auto Repair in Longmont can quickly diagnosis what is causing your parasitic car battery drain so you won’t have to deal with the hassle of a recurring dead battery!

Most Common Sources of Parasitic Car Battery Drain

  • Lights- in the glovebox or trunk
  • Alarms– According to Popular Mechanics, “Aftermarket alarms are notorious for sucking healthy, fully charged batteries dry within a few days. If you have any non-factory alarms, it’s the first thing you should check.”
  • Stereos– Although designed to go into a standby mode that draws only a couple milliamps, several hundred milliamps can be drawn if the DIP switches are improperly set.
  • Proximity Keys– The convenience of not having to dig out your key to unlock or start your car can become a major inconvenience if it drains your battery. The job of your proximity key’s radio receiver is to check for a match everytime it gets a signal at it’s frequency- this can result in a dead battery if parked for an extended time in an area where many other keys pass by.
  • Electronics plugged into the lighter– Cellphone chargers, GPS units and other cords that plug into your car’s power should not draw more than a few milliamps when the device is not connected.


If you’re not sure why your car’s battery keeps dying, bring your it in to Best Auto Repair of Longmont for a quick check for parasitic battery drain and get your vehicle starting reliably again!

Call Us For an Appointment


Connect With Us:

Best Auto Longmont
1840 Delaware Place Unit C
Longmont, CO 80501
Phone: 720.652.7272

Monday - Friday
8:00 AM - 5:30 PM
Saturday - Sunday