Voltage Drop Testing

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Voltage Drop Testing

Postby Chris_W » Tue Oct 16, 2012 12:14 pm

Right, first off the basic story of the Car.

1999 Renault Laguna DTi presented with overheating issue. If no electrical items are switched on the vehicle runs fine and the cooling fan cuts in at approx 3/4 up the gauge. If you then switch on electrical items such as Rear Screen heater, heater blower etc the temperature gauge rises up to virtually off the scale but live data says the car still isn't past approx 96 degrees and the fan still cuts in and out as it should.

Using my (lack of) knowledge I thought maybe a build up of potential on an earth, so thought i'd play with the scope.

If I did this right (waveform attached) then i indeed do have an earth fault. I connected the ChA reference to battery and the ChA signal to the block and then disabled starting (does that sound right?).

I appear to get approx 1v drop during cranking and that seems high to me?

All thought/comments/criticism welcome :D
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Re: Voltage Drop Testing

Postby Robski » Tue Oct 16, 2012 2:06 pm

now do the same again with the alternator under load, grab an alt ripple too loaded/not loaded.
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Re: Voltage Drop Testing

Postby Chris_W » Tue Oct 16, 2012 2:12 pm

I would, but I already appear to have fixed it. Bad engine and body earth points.

I can still get them if you like, not sure how but I can make it up! :D
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Re: Voltage Drop Testing

Postby Robski » Tue Oct 16, 2012 2:29 pm

too late if fixed, it would have been practice for you :wink:
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Re: Voltage Drop Testing

Postby Chris_W » Tue Oct 16, 2012 2:37 pm

Practise is always good. There doesn't seem to be any courses in Lincolnshire to learn the thing so I guess it's going to be hands on learning!
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Re: Voltage Drop Testing

Postby Robski » Tue Oct 16, 2012 2:56 pm

You will have to travel.......
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Re: Voltage Drop Testing

Postby Chris_W » Tue Oct 16, 2012 2:59 pm

I'm happy enough to do that, try telling my boss! :(
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Re: Voltage Drop Testing

Postby 4d » Tue Oct 16, 2012 6:50 pm

Where in Lincolnshire are you Chris as I am in Lincoln and often travel some distance to training courses so could poss car share if ever doing the same ones

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Re: Voltage Drop Testing

Postby Chris_W » Tue Oct 16, 2012 7:01 pm

Hi Carl.

I'm at Louth, so maybe 25 miles from Lincoln. Lift sharing sounds good to me, let me know when/where you're going and we'll see if we can set something up.

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Re: Voltage Drop Testing

Postby joshua1 » Fri Oct 19, 2012 12:07 pm

Hi everybody,
Voltage Drop testing process is very important.....Is there any tool or software to test this?? How can we test without any problem.....
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