How To Find A Parasitic Draw On Car Battery

Measuring Parasitic Describe

All vehicles describe some ability from their batteries when the automobile is shut off. Vehicles with onboard computers have Random Access Memory (RAM). And accessories such equally clocks, audio systems (station presets), seats (Automatic Drive Positioner, or ADP), remote door openers, and security systems also need ability to maintain retentivity when the ignition is OFF. Each device with memory has a different amount load. The power used equally a event of this continuous energy or cumulative load is called parasitic draw. It is usually a very small describe and then the battery doesn't become drained. Parasitic loads can run twenty to 120 milliamps. If there is an electrical short in the vehicle or a malfunctioning accessory it could draw more than its normal load causing a large drain on the bombardment.

In gild to check for parasitic draw, a Digital Multi-Meter (DMM) that tin handle a minimum of 1 milliamp and up to 10 amps is needed to perform a parasitic draw test.

Vehicle Grooming

1. First fix the vehicle for the parasitic depict test past making sure the battery is charged. Weak batteries don't requite accurate results when performing a depict test. In add-on to diagnosing and charging a weak bombardment (or if you installed a new i to replace a dead one) brand sure to verify that the charging organisation is operating properly.

2. Turn the ignition OFF, then brand sure all electrical accessories are OFF, too. This includes unplugging anything plugged in a power socket(south).

3. Disconnect the electrical connector for the Anti-Theft Organisation Hood Switch (if equipped).

4. Close the Hood.

five. Operate the vehicle to simulate client functioning. Run the engine, drive the vehicle, terminate the engine, release the hood latch, get out and lock the vehicle.

6. Digital Volt Ohm Meter (DVOM) Preparation (refer to the operating instructions provided with meter).

a. Set DVOM to measure DC Amps on the highest calibration (commonly 10A).

b. Motility the DVOM ruby atomic number 82 to the Amps position in the meter.

Vehicle Preparation for Measurement

i. Open the Hood.

2. Expect at least 60 minutes to allow all systems to enter sleep mode. To go a correct reading, the vehicle should be left with the doors closed and the ignition OFF for an hour before start the test.

3. Select Ammeter, and then connect the leads.

The most hard office of making a parasitic draw measurement is establishing a "shunt" connectedness through your DVOM prior to disconnecting the terminal cable from the negative battery mail.

a. Loosen, simply Do Not remove the negative battery last.

b. Connect the red pb to the negative battery cable end.

c. Connect the black lead to the negative battery mail.

4. Carefully remove the negative battery cablevision without breaking the shunt connection while removing the terminal cable from the bombardment post. Brand certain the DVOM leads remain fastened to the battery post and cable finish. It's imperative that you keep this connectedness to avert sending one of the modules back into an initialization process which boosts current menstruation. This may not blow the meters fuse, but information technology will definitely requite you an incorrect reading. You will accept to wait until that procedure completes and they are ready to become to sleep earlier y'all can endeavor again. The Ammeter should then be able to give y'all an accurate Parasitic Depict (Dark Electric current) measurement.

Determining the Source of Parasitic Draw

If the ammeter reading exceeds 23 mA, something may be using likewise much ability. If excessive parasitic depict is present it volition demand to be corrected and so the battery does not drain. To determine the source of Parasitic Describe (Dark Current), start past checking for aftermarket accessories. If whatever aftermarket accessories are nowadays, remove the ability to these accessories, so retest.

Finally, follow normal diagnostic procedures to identify source of draw. If y'all take a high reading, y'all'll need to check each component. For example, remove fusible links, fuses, relays, etc., one at a fourth dimension until the draw is isolated to the offending electric component/system. Open up the door, and tape the door switch open circuit so that the system returns to sleep mode. And then, remove each fuse one at a fourth dimension to isolate the circuit causing the depict.

The under hood fuses can be removed without too much difficulty, and without waking upwards the BCM. If you can't identify an excessive draw by removing the fuses, and the components cheque out fine, you may have a wiring trouble.

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Source: http://www.nissantechnicianinfo.mobi/htmlversions/Winter_2012/Parastic_Draw.html

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