Closed-Circuit Current Measurement - BMW 5251 Service Manual

Battery, Starter, ~lternatorl
WARNING-
Always wear protective goggles and clothing when perform-
ing a load test.
Table d. Battery load test
-
minimum voltage
Ambient temperature Voltage*
27 "
C
(80" F)
9.6 V
-I 8'
C
(0" F) 8.5 V
*
Measure after applying a 200 amp load for
15
seconds.
Closed-circuit current measurement
If the vehicle battery is discharged for an unknown reason,
perform a closed-circuit current measurement as the first test.
For diagnostic purposes, it is important to not disconnect the
battery. Disconnecting the battery may reset a faulty control
unit, preventing proper diagnosis.
The following test is generally completed overnight using a
multimeterwith a closed circuitcurrent measurement adaptor
with a recording function
-
Check that battery voltage is 12 volts or higher. If lower,
recharge battery.
-
Switch off electrical consumers (interior lights, telephone,
aftermarket equipment, or others).
-
Open luggage compartment and remove battery trim panel.
Use screwdriver to lock latch on trunk lid or hatch, simulating
closed luggage compartment. Close other doors.
-
Open driver's door, then close it, simulating driver entering
vehicle.
-
Switch ignition to RUN position for at least five seconds, then
turn ignition to OFF position. This simulates driving vehicle.
-
Open and close driver's door, simulating driver leaving
vehicle.
-
Lock car and arm alarm.
-
Wait at least 16 minutes for consumer cut-off.