volt drop test

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dingo
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volt drop test

Post by dingo » Wed Mar 04, 2009 8:04 pm

http://www.aa1car.com/library/voltage_drop_testing.htm

very enlightening stuff...and helped me to diagnose a bad ground connection. IN short, set Voltmeter to 2V scale and attach the two leads along any segment of cable...read while cranking. e.g. i tested my new ground cable by readin volt drop between Batt(-) and the ground connection on frame..it read 0.1 V, which is OK. Same can be done on pos cable
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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dingo
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Post by dingo » Thu Mar 05, 2009 10:40 pm

'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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skin daddio
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Re: volt drop test

Post by skin daddio » Fri Mar 06, 2009 9:01 pm

dingo wrote:http://www.aa1car.com/library/voltage_drop_testing.htm

very enlightening stuff...and helped me to diagnose a bad ground connection. IN short, set Voltmeter to 2V scale and attach the two leads along any segment of cable...read while cranking. e.g. i tested my new ground cable by readin volt drop between Batt(-) and the ground connection on frame..it read 0.1 V, which is OK. Same can be done on pos cable
Voltage always follows the path of least resistance, so if the circuit or connection being tested has too much resistance some of the voltage will flow through the DVM and create a voltage reading.
timely stuff, i'm getting the notorious click before having to re-ignition on the sunroof. wish my meter was digital.

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dingo
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Post by dingo » Fri Mar 06, 2009 9:55 pm

i like having one digital and one analog..both have their merits.

Tested the volt drop on the pos. side and got 0.13 V..so thats cool

but when i crank the starter, the batt volt drops down to 9V*..which is way out of range..so either my Batt is crap or the starter is tired.

*good instance of Analog being better than rapidly jumping digits
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

vdubyah73
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Post by vdubyah73 » Sat Mar 07, 2009 6:11 am

dingo wrote:i like having one digital and one analog..both have their merits.

Tested the volt drop on the pos. side and got 0.13 V..so thats cool

but when i crank the starter, the batt volt drops down to 9V*..which is way out of range..so either my Batt is crap or the starter is tired.

*good instance of Analog being better than rapidly jumping digits
Or your battery cables and ground straps need cleaning/replacing
1/20/2013 end of an error
never owned a gun. have fired a few.

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dingo
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Post by dingo » Sun Mar 08, 2009 7:17 pm

-where do i locate the infamous 'ground strap' ? somewhere on tranny ?

- my Batt reads a constant 12.23 V even after being charged...slightly low
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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Amskeptic
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Post by Amskeptic » Sun Mar 08, 2009 9:34 pm

dingo wrote:-where do i locate the infamous 'ground strap' ? somewhere on tranny ?

- my Batt reads a constant 12.23 V even after being charged...slightly low
At the left diagnonal link's pivot bracket, you should see one end, the other goes to the transaxle mating flange under a 13mm nut. Looks like a braided battery ground strap from the factory.
Colin
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dingo
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Post by dingo » Mon Mar 09, 2009 6:00 pm

ok found it...pretty sorry looking and corroded. What do you put on or over connections to prevent imminent rust/corrosion ?
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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skin daddio
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Post by skin daddio » Mon Mar 09, 2009 6:38 pm

nothing, but if i did, if really had to, i'd encourage the area with scented vasaline.

vdubyah73
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Post by vdubyah73 » Mon Mar 09, 2009 7:07 pm

Gob of wheel bearing grease. clean and regrease it once in a while. If it is a corroded mess a regular battery cable with eylets on both ends works fine.
1/20/2013 end of an error
never owned a gun. have fired a few.

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