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bish789



Member Since: 30 Apr 2012
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You're all missing one question I think, is the additional earth the same cross sectional area as the installed one, or is it bigger/smaller?
This will affect the results as in this case, size does matter Laughing
Perhaps oldgeezer can answer this fundamental question?
Don't just presume the current will be equally split.

Post #169797 30th Jan 2013 7:08 pm
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mudslinger



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guess how many AMPS travel down my additional earth cable

It depends what type of earth cable you have ,and if it was one of those manufactured a few years ago
(with little arrows on the insulation to show which direction the "current has to flow "... )


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Post #169832 31st Jan 2013 8:17 am
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chicken george



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Surely the volts remain the same across several earths but the amps are divided across the number of leads? They cant all carry max amps each At work
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Post #169845 31st Jan 2013 9:52 am
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pab



Member Since: 28 Aug 2012
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bish789 wrote:
... is the additional earth the same cross sectional area as the installed one

You are correct that this will make a difference, as will various other factors such as the length of the respective cables, the nature of the connections between the cable and whatever it is connected to, the route between the cable termination and the load, etc. So yes, I'm assuming too much! But in practice the difference may not be as simple as the ratios of the cross-sectional areas. There are so many unknowns (we could even get into considering whether there is an alternating element to the current as the starter turns, and therefore whether we need to consider inductance effects - but let's not!) that measurement is really the only way to know.

So my figures may well be on the high side, based on incomplete knowledge.

Post #169849 31st Jan 2013 10:04 am
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pab



Member Since: 28 Aug 2012
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United Kingdom 2009 Freelander 2 TD4 XS Manual Lago Grey

Quote:
Surely the volts remain the same across several earths but the amps are divided across the number of leads? They cant all carry max amps each

Correct. But the division may not be equal if the cables are of different cross-sections and lengths.

Quote:
arrows on the insulation to show which direction the "current has to flow "

Yes, if it is I hope he's got it the right way round Smile

Erm, but what *is* the right way round given that batteries both charge and discharge...!

Post #169851 31st Jan 2013 10:12 am
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nicedayforit



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The suspense waiting for the answer is killing me. Laughing

Post #169861 31st Jan 2013 12:05 pm
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chicken george



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So if og, s new lead is showing high amps it shows the origonal was weak At work
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"I can't always believe facts I read on the web" - Charles Dickens

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Post #169864 31st Jan 2013 12:41 pm
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taztastic



Member Since: 03 Feb 2011
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We know his original cable was weak, it had corroded and his "miracle" cure of a new cable seems to have cured his ills, this is fact but why we need to guess how many amps flow through it is beyond me.
You can fit a second earth strap to a perfectly good car and you will get a reading of current flow, so what it proves is negligable really, if you could measure the impedance of the circuit and determine where any resistive areas where located that may be useful, in this case its nonsense that provides very little in the way of a solution to remedy the cause rather than just treating the symptoms, which largely dont seem to be occuring in hundreds of thousands of cars. Rolling Eyes

Post #169870 31st Jan 2013 1:01 pm
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pab



Member Since: 28 Aug 2012
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Agreed, Taz. OG does say, though, that the original cable has now been replaced by LR, so what would be interesting would the the comparison of current in the original and supplementary cables. If the latter is similar or less it tells us nothing (except that things are as we'd expect). But if the current in the supplementary is higher it would tend to support OG's contention that the original earthing is inadequate. Just the current in the second cable alone tells us nothing useful.

Post #169871 31st Jan 2013 1:10 pm
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chicken george



Member Since: 05 Dec 2007
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we had a tractor with a bad earth connection, countless warning lights for various functions popped up on the display screens, quickly fixed once we stopped panicing and no damage done. so always a good idea to regularly clean your earths.

defenders we had had a similar problem the earth bond, body to chassis used to fail At work
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Post #169887 31st Jan 2013 3:05 pm
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npinks



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is anyone else getting a little bored waiting Laughing Former Mod/Member, with the most post & Chicken George Arch nemesis

Post #169894 31st Jan 2013 3:27 pm
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hinchy



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Didn't sleep last night cus of it Yawn

Post #169896 31st Jan 2013 3:38 pm
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JST



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Post #169907 31st Jan 2013 4:45 pm
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bish789



Member Since: 30 Apr 2012
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Let's throw another one into the equation while we're waiting.
Conventional v true current flow Laughing Laughing Laughing Laughing Laughing Laughing

Post #169911 31st Jan 2013 5:10 pm
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taztastic



Member Since: 03 Feb 2011
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He does say "up" and " down" so may have that covered, although will more flow down due to gravity Laughing

Post #169912 31st Jan 2013 5:17 pm
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