Prevent Battery Drain in Your Car – Everett Battery Service & Replacement

September 17, 2011  

You’re running late, the meeting will start without you! You’ve got everything  planned to the minute – and the car won’t start…arrrrgh! So, you use your husband’s car to jump the battery – whew, it starts…all is well with the world. Until, that night, after working a 14 hour day, your car won’t start again! Chances are, your  first instinct is to think it’s time for a new battery…except you realize this is a new battery. Sounds like something is draining your battery. This is  where Everett Battery Service & Replacement comes in – the technicians will determine what exactly is draining the battery and repair the problem.

Normal Battery Draw

The majority of vehicles do draw some current, even when the key is “off”. Several systems operate when the engine is turned off, including but not necessarily limited to:

  • Clock
  • Radio Presets
  • Engine Computers’ internal memories
  • Body-Control Modules
Chances are, however, the combined draw from such components is not more than 50 milliamps. To determine the specific draw, check your Owner’s Manual.

Measuring Draw

To measure your vehicle’s car-off draw, all it takes is a muti-meter capable of measuring as low as 200 mA up to 10 amp to 20 amp. To assure that the reading is accurate, be certain to:

  • Deactivate Door Switch – by either shutting all doors or wedging the switch(es) shut. With door(s) open, several circuits are activated (fuel pump, interior lights, etc.)
  • Unplug Chargers – car chargers plugged into lighter sockets draw current (cell phone, GPS, etc.)
  • Disconnect Auxiliary Stereo Equipment – some speaker components go to “sleep” rather than completely turning off

Now that all excess drains have been disabled:

  1. Check draw on the battery. Disconnect the ground cable of the car’s battery. Connect the meter (set to highest reading) between the battery ground terminal and the just disconnected cable. If the reading is higher than the combined drain of the car-off components, you have “unauthorized battery drain”.
  2. Determine Draining Circuit. To determine the circuit that is draining your car’s battery charge, you could check each circuit by removing fuses, one at a time, and checking the draw across the circuit. Once you’ve discovered the draining circuit, you will need to find the specific component within that circuit that is causing the excessive drain.
  3. Specific Component Drain. To determine the specific component within a circuit that is causing excessive battery drain, you will have to check each component’s draw. This requires reading the wiring diagram of each circuit and running the test across each component.
Alternate Test

The best way to determine where the battery drain originates – have the experts at Everett Battery Service & Replacement run the tests! Because their technicians are fully trained and certified, and have the instruments and tools necessary for a safe, effective system test, your vehicle will be diagnosed and repaired much more quickly than trying to perform the work yourself.

Most Common Draining Components

  • Alarms – especially aftermarket products, often drain the car battery. Many times, after market installations are not spliced into the car’s electrical system 100% according to factory standards. Should you decide to have an aftermarket alarm installed on your vehicle, be sure to have the technicians at Everett Electrical System Service & Repair check the wiring.
  • Stereos – if you have an aftermarket stereo wired directly to the battery, chances are it will draw down the power. Often, the stereo components do not completely turn off, rather they go to sleep (standby). If the switching is not set correctly, the stereo components may not go to standby, but continue drawing full power.
  • Proximity Keys – every proximity keyed lock, “wakes” up when any proximity key is in the vicinity. If you leave your car parked for an extended period of time in, say an airport parking lot, every time a proximity key passes, your lock attempts to match and unlock. Although the actual awake time is only one to two minutes, over time, the draw adds up to a drained battery.