b'QUIESCENT DRAIN - TYPICAL VALUESNOTE: The quiescent drain after the initial shutdown period should not exceed the value shown in the table.BRAND MODEL SHUTDOWN PERIOD TYPICAL BATTERY DRAIN VALUESLand Rover All 30 minutes 30 mA (ave. over 10 min.)The total current drain will be higher if certrain approved accessories are installed. For example: tracker, trailer module.Figure 7: On Land Rover vehicles, the quiescent (resting) current should remain less than 30 ma, unless there are add-on accessories such as a trailer module, then slightly higher amounts can be acceptable. Next, rig in your shunt resistor. Figure 5 shows athat the max quiescent drain on any vehicle should version of this tool. This shunt tester is based on anever exceed 50 ma.0.1 ohm power resistor rated at 100 watts. As youItisatthispointwiththecurrentdrainpresent can see in the picture, we have simply soldered ourthat we want to begin to use the scope or meter to wires to the resistor, fused the device at 10 amps,voltagedropeachfusetoisolatewhichcircuitis andprovidedattachmentclipsandscopelead connections directly to the shunt tool.usually need to be taken in stepsmeaning testing Theshuntresistorusedhereallowsustouse thevoltagedropacrosstheresistortoaccuratelyway to test the plastic cage fuses if needed. (This calculatehowmuchcurrentisdrainingwithoutis where the LR bulletins recommendation to use anyprobedriftinfact,withouttheprobeatall.a current clamp may come in handy at the output Because you are measuring the voltage drop throughdevice or near the fuse box, in situations where you a known value resistor, you can set the scopes mathcannot get to the fuse.) channels to calculate the Ohms Law results for youInterpreting the Test Resultsand display a stable real-time current value, as wellThedropinvoltageacrosstheshuntresistor as record both the current and voltage activity anddisplayedon the scope or DVOM equals the total data during the test. current draw in that circuit, in terms of millivolts or Attach your voltage leads across the shunt resistorvolts. Use Ohms Law or a math channel to calculate andsetyourscopefortheslowestrecordtime orsweepspeedpossible.OntheTiePieandPicoIf you are only using the current clamp and meter andFOLLOWScopes, this can be set around 500 to 5,000 sweeps per division or so. You can calculate this, then simplynot a scope and math channels, simply compare theSSF ONadjust the sweep speed to achieve the record timemillivolt reading you obtained across the fuse to any you desire.published fuse resistance chart (a Google search willFACEBOOKreturn many available fuse charts to interpret what Wherepossible,rigtheshuntinserieswithyourthe current drain value is for that individual circuit).thebatterycabletostartthetest.Ifyoudothis(again, without disturbing the fused circuit) perform step creatively, you will not lose connection to yourisolationofconsumerloadsonthatfusedcircuit battery nor need to reset all of the memory settings. Onceyourbatterycableisdisconnectedandall current is running through your shunt resistor, youThebeautyofusingyourscopeforthesetestsis arenowmonitoringalllivecurrentthroughyourthatwecanseethephysicalmechanismsinplay shunt resistor. continuously and graphically over time. The faults, anyglitches,powersandgrounds,currentdrains, at 30 ma or less, but there are vehicles out thereand voltage drops, we can isolate the fault quickly thatwilldrawabove30manormally.Watchforonce the drain is in play using these creative methods. SSFIMPORTEDAUTOPARTSany current activity to appear, above the commonlyRemember,yourejustguessingwithoutphysical held rule of thumb of 25-40 ma. Rules of thumb saytesting. Until next time, happy diagnosing! |28'