Testing Grounds
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Joined: Jan 2001
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From: Virginia
Originally Posted by Beemer Nut
Fluke 77 for work, Fluke 87 down to .1 ohm for automotive use at home.
Use a conductive anti-corrosion compound like by Thomas & Betts called KOPR-SHIELD.
This applied to clean terminals be it battery, starter relay, starter and all grounds you will have no surprise electrical phenomenons with resistance less than 1/10 ohm.
Be surprised how fast your starter will crank even with a hot motor.
Use a conductive anti-corrosion compound like by Thomas & Betts called KOPR-SHIELD.
This applied to clean terminals be it battery, starter relay, starter and all grounds you will have no surprise electrical phenomenons with resistance less than 1/10 ohm.
Be surprised how fast your starter will crank even with a hot motor.
Let's be optimistic, and guess the starter can turn the engine over with 8 volts. That's a 4 volt drop. 4 volts divided by 100 amps =.04 ohms resistance.
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Post Fiend
Joined: Dec 2003
Posts: 6,658
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From: "Islander"
Franklin; the Fluke 87 will read down to minimun of .1 ohm.
Before zeroing the test leads that are 48" long each i'll read .3 ohms,
zero the leads by the REL button I can read .000 ohms at every connection starting from the battery posts, starter relay, starter terminal to lead and battery to block ground. All at .000 ohms. NO VD here (not the disease type either).
I believe the Fluke 88 will read down to .01 ohms but not in the budget at this time but me wants.
Before zeroing the test leads that are 48" long each i'll read .3 ohms,
zero the leads by the REL button I can read .000 ohms at every connection starting from the battery posts, starter relay, starter terminal to lead and battery to block ground. All at .000 ohms. NO VD here (not the disease type either).
I believe the Fluke 88 will read down to .01 ohms but not in the budget at this time but me wants.
Elder User
Joined: Jan 2007
Posts: 612
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Originally Posted by Beemer Nut
I believe the Fluke 88 will read down to .01 ohms but not in the budget at this time but me wants.
Like Franklin said, if you had .1 or .2 or .3 ohms of resistance in any high current ground, whatever is connected to that ground would not work.
I am not randomly making **** up when I say testing the resistance with a multimeter is useless. I have a $5,000 digital phosphor oscilloscope at home that is so accurate it would make the most expensive multimeter ever invented look like a Wal-Mart special, and even it has trouble reading below .3 ohms accurately. And it costs $5,000!!!
So I will say it one more time. Using a multimeter to test resistance in a circuit with less then .001 ohms of resistance is a utter waste of time and anyone who thinks its telling them something useful obviously does not know what they are doing and should take it to a professional!
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Originally Posted by SPL Tech
So I will say it one more time. Using a multimeter to test resistance in a circuit with less then .001 ohms of resistance is a utter waste of time and anyone who thinks its telling them something useful obviously does not know what they are doing and should take it to a professional!
I told the OP to check for 1 or 2 ohms, which many multimeters can easily detect (mine can and it cost $20). I did not say it is a fail-safe method, I simply said it has worked for me in the past. If it is the general consensus that even an ohm or two can throw off a ground then I will save that knowledge for future use. If I interpreted your comment in the wrong way then I apologize.
Post Fiend
Joined: Dec 2003
Posts: 6,658
Likes: 4
From: "Islander"
fmc; it's not against you or me I hope, i'll step a side with my cheapo radio shack Fluke 87 as these high tech 40 year old trucks electrical is far beyond my ability to trouble shoot. I'll go back to licking terminals with tongue like testing those 9 volt batteries and tell Fluke they sold me a meter that is a useless POS when I should of had a $5,000 meter instead.
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