Mud-club
Vehicle & Technical => Range Rover => Topic started by: MZ6666 on December 20, 2006, 19:24:38
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Howdy folks,
My mate has a problem with his P38 2.5 Diesel Rangie. It keeps flattening the battery. He's had a volt meter on it and has discovered that when the interior light is on it's drawing minimal current but as soon as it goes off ,it draws around 3.8v.
Any ideas
Cheers,Rich
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What is he actually measuring? 3.8v is not a current reading.
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Not sure. He just said it goes from a minimal reading to 3.8 when the light goes off? I presumed it was volts but I was never very good at the amps/ohms/volts thing :oops:
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If he is measuring volts across the battery it should be 12 or thereabouts regardless of waht is on or not. If he is only 3.8v the battery is either very flat or goosed.
I had the smae last week; the cold weather will show up a duff battery and much as I love the P38 it is very battery dependant.
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He reckons its had about 3-4 batterys since new ,which seems excessive to me?
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Where does he park it? Apparently the P38 is prone ot the ECU 'waking up' from other sourses and flattening the battery. The best I heard was a weather station on the key frequency.
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Usual sort of places I suppose. Although he does work near (3-4 miles) a radio mast. :idea: Could that really effect it?
However the readings weren't done while he was at work.
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Depending on how he's reading it. But the reading over an interior light bulb is meaningless.
Between earth and one end of the bulb will give 0 volts or a few millivolts when off. This is because one end is earther to turn it on.
Between earth and the other end will normally give +12-+14V when its off.
Current is measured in Amps (A) not Volts (V). Voltage is measure between two points (in parralel) and current in line (series). Dont try to measure current on a normal multimeter as you'll almost certainly toast it :) Use a clamp-meter.
Measure it accross the battery terminals. At rest it should be between 12V and 13V. Anything lower indicates a possible faulty battery or a heavy drain on it. Do this with the ignition off.
Start the engine, you should see about 13.5V - 14.0V or a lil higher. If its too low, new alternator regulator, brushes or whole unit required. Too high and regulator/alternator and probobly a new battery needed.