Battery: Testing and Inspection
Battery and Charging System - General Information - Quiescent Drain
Description and Operation
VEHICLE QUIESCENT CURRENT TESTING
On vehicles fitted with a Battery Monitoring System (BMS), the diagnostic routine for quiescent drain testing in the approved Jaguar or Land Rover diagnostic system should be utilized.
If a customer complains of a vehicle battery that discharges continuously or when left for a prolonged period of time, it is recommended that a quiescent drain test is performed as described below.
The battery drain should be measured using the approved Jaguar or Land Rover diagnostic system or a Digital Multi-Meter (DVOM). A procedure for quiescent drain measurement using the diagnostic system is available in the Diagnosis and Testing section of the Workshop Manual. The vehicle should be in the locked/armed state (for example vehicle alarm fully armed), all doors, engine and luggage compartment lids are open and latched (so as to appear closed from an electrical point of view). The test should take place after the vehicle has entered shutdown mode. The time taken for this to occur after the ignition is switched off varies according to model (Refer to the Topix On line resource for details).
When the vehicle is armed, the effect of the security system Light Emitting Diode (LED) flashing is to cause a pulsation in the measured current drain. In this case, either the average current should be taken (using a Digital Multi- Meter (DVOM) with an averaging system) or the current reading taken, ignoring the brief high current peaks.
EQUIPMENT
Approved Jaguar or Land Rover diagnostic system with current probeOR Digital Multi-Meter (DVOM) with current probe.
METHOD OF MEASUREMENT
Using an Approved Jaguar or Land Rover Diagnostic System.
- Switch off all electrical loads and ensure that the ignition is off
- Connect the current probe to the approved Jaguar or Land Rover diagnostic system
- Calibrate the probe
- Install a clamp around the battery lead/junction box lead
- Go to the Quiescent Current Testing section in this procedure
Using a digital multimeter
Do not use an in-line DVOM to measure the quiescent drain on vehicles fitted with an electronic throttle (for example Range Rover 2002MY onwards). The current exceeds the maximum amount the fuse in the DVOM is capable of handling.
- Switch off all electrical loads and ensure that the ignition is off
- Connect the current probe to the digital multmeter
- Calibrate the probe
- Install a clamp around the battery lead/junction box lead
- Go to the Quiescent Current Testing section in this procedure
QUIESCENT CURRENT TESTING
- Switch ignition to 'on' or select ignition mode in keyless vehicles and switch to 'off' (do not crank)
- Remove key from ignition switch (if equipped)
- Open and latch all doors, hood and luggage compartment lid
- Lock the vehicle using the remote function on the remote handset. (Single lock only to avoid volumetric alarm arming)
- Remove any other potential electrical drains such as accessories plugged into accessory sockets
- Record the amperage readings after the shutdown period referenced in the Topix on line resource for details. Note all cars from 10MY onwards should be less than 30mA after 30 minutes
- Record the final reading on the battery report form
The preferred method of testing following an excessive current consumption figure is to use a current probe around individual junction box leads to the various suspected circuits to identify a potential cause. This is in preference to the old method of removing fuses for the following reasons:
- The drain may be caused by a module remaining active and preventing the quiescent drain from reducing to normal levels
- The drain may be caused by a relay winding that is activated. Pulling the fuse can allow this to �reset� and the drain will be lost and go un-diagnosed
Land Rover Quiescent Drain Values
NOTE:
1. The total current drain will be higher if certain approved accessories are fitted (for example: tracker, trailer module, etc.)
2. Applies to vehicles without Tire Pressure Monitoring System (TPMS). Vehicle shut-down period with TPMS is approximately 15 minutes.