Ste M
Member
Registered: 28th Oct 09
Location: Blackpool
User status: Offline
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Hi guys.
I've got a parasitic battery drain on the car, I've watched several different videos and they all show different ways to check.
Now what I'm thinking is, you need a multi-meter (obviously), connect th8e red wire to the 10A jack, set the meter to 10A, then disconnect the negative wire on the car battery, then place one probe on the battery negative terminal, whilst the other touches the wire (whilst disconnected) and it should read around 0.2 amps.
Is this correct?
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Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
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In series with the draw so yeah, disconnect the pos terminal and put your meter between that and the terminal on the battery.
Don't try and start it or run the heaters or anything else which will draw a lot of current.
Lights etc. are fine.
If you have a trace, pull each fuse in turn and watch for the trace to change. More difficult if there is more than one thing drawing current but it'll give you an idea.
[Edited on 29-12-2011 by Ian]
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Ste M
Member
Registered: 28th Oct 09
Location: Blackpool
User status: Offline
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Do you mean the positive and not the negative? Or do you mean disconnect the positive so it doesn't blow my meter?
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Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
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Disconnect the pos from the battery and put the meter between the pos terminal on the battery and the wire you just just took off.
So the meter completes the break.
You'll only blow the meter if you draw large currents.
[Edited on 29-12-2011 by Ian]
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Ste M
Member
Registered: 28th Oct 09
Location: Blackpool
User status: Offline
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You'll have to bear with me, I'm a complete electronics newb!
I understand the disconnecting the positive wire (lol) - so then I place what colour wires were? The black (COM) probe to the positive terminal and red probe to the positive wire?
And is this with the negative wire connected or disconnected from the battery?
Is what you're saying the way I said how I thought I should do it with the negative, but do it with the positive?
Christ, I feel so thick.. lol 
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johnhara1
Member
Registered: 19th Oct 06
Location: Newcastle upon Tyne
User status: Offline
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Yes, put it between the positive terminal on the battery and the wire from the positive on the battery.
So, you have a meter on the positive.
Then, when your mate starts pulling fuses in the fuse panel, you can watch for fluctuation on the meter and find your drain.
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Ste M
Member
Registered: 28th Oct 09
Location: Blackpool
User status: Offline
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Fantastic, thank you 
So is doing this process with the negative wrong?
Edit: One last thing; should the negative be disconnected? I'm reading that disconnecting the positive first can be risky..
[Edited on 29-12-2011 by Ste M]
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johnhara1
Member
Registered: 19th Oct 06
Location: Newcastle upon Tyne
User status: Offline
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No, don't disconnect the negative as you're breaking the circuit and you'll not find the drain.
Battery has to be connected for it to be drained 
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Jon_C
Premium Member
Registered: 7th Dec 05
Location: Suffolk
User status: Offline
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Spent ages yesterday doing this with my best mate on my car. Was a nightmare. We set up the meter and just sat pulling fuses out one at a time looking for a drop in the drain on the battery. Mine turned out to be my headunit wiring.
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Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
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You can put the meter across the negative, doesn't make much odds, just might mean you don't get as good an earth to the chassis.
Aftermarket HU would be the first place I looked
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Jon_C
Premium Member
Registered: 7th Dec 05
Location: Suffolk
User status: Offline
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Mine was the wiring loom to the headunit in the car loom. Was massively bodged. wasnt til i pulled it all out that we realised
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