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Voltage drop.


JJ7893
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Hi all long time no see lol, Right I been having a problem with the car electrics. Every 2 days the battery would be flat as a pancake, So what could be the cause? All I can say is the passenger floor has been socked in very heavy weather, So I took all the relays out took them apart, Sprayed WD40 in then shake it then put it back together (Did this 1 by 1 so there no mix up). The Brown relay has been giving me problems if I move the wire or relay the hazards starts up and will not go off until I turn on the ignition on as I'm just going to start it up then it goes off then it remains like that. Any idea's? cheers for any help that comes forward ........JJ

Forgot to add it's a ES Discovery L reg 2.5TDI

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You need to measure whether something is draining the battery - connect a meter in series with the battery (don't turn anything on or you will fry the meter) and see what the current drain is with everything off.

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How about whats known as methodical disconection, to give it, its posh name.

Remove the fuse from a few circuits, its up to you what you choose,

Then wait...

If the battery still goes flat, then there is fault is one one of the still connected circuits.

Repeat as required intill you can provwe the circuit.

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Thanks for your reply's, First off I tested the battery with out the earth being on, and it reads at 11.1 volts (this has been like that since 30 May). So disconnected the alternator and it did not move then took each fuse out one by one and nothing happened! Then I took the relays out still nothing. Then I ran the engine tested it and it was reading at 13.3 volts. So now I made sure everything is off even the face of the radio unit is off and see what happens tomorrow. Or is there something I have done wrong? .......JJ

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11.1v is an unhealthy battery.

A healthy, charged battery should sit at 12.5v. Whilst charging the battery should be at 13.8v to 14.4v

Have you actually taken a reading of the current draw with the engine/vehicle turned off?

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if you want to prove its not the battery which is the simplest of the lot, run it well to charge it then disconnect it (obviously when youve switched off the engine) then leave. Come back next day or 2 days later, reconnect and if theres no life the battery is duff.

Dave

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I have left the battery for a few days and nothing happened to it I have put it on full charge but that was before I played with the electrics. I put it on full charge again and see what happens ......JJ

P.s how do you do this?

Have you actually taken a reading of the current draw with the engine/vehicle turned off?

Thanks again .....JJ

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P.s how do you do this?

Have you actually taken a reading of the current draw with the engine/vehicle turned off?

Set your multimeter to amps and place it in series with the battery. i.e remove one terminal, put one probe on the battery and one on the disconnected cable.

If you see amps, something is drawing current. Remove fuses and relays etc until the current stops, and you've found your culprit.

Measuring the voltage of the battery while removing fuses etc won't work, unless there's something huge drawing current.

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13.3v wont properly charge a car battery either.

You need a minimum of 13.8v, preferably around 14.1v to correctly charge a 6 cell lead acid battery.

Might want to check the earths between the alternator and chassis.

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