Battery cable re-do

[015point9]

The lead part on battery that goes to battery broke, I cut cable back about an inch.  I dont see any visible corrosion.

(Drop voltage test?)  When I put one end of the now cut off lead lug i lose 1 volt at other end.  And with volt meter i  can get a beep doing a continuity test.  

 

Any suggestions for a proper elec test in order to ensure stock cable good or not.  

 

Thanks

[Timd32]

This was a good article I dug up a while back.

 

https://www.fluke.com/en-us/learn/blog/automotive/electrical-automotive-troubleshooting

[015point9]

 

8 minutes ago, Timd32 said:

This was a good article I dug up a while back.

 

https://www.fluke.com/en-us/learn/blog/automotive/electrical-automotive-troubleshooting

Thanks... I actually started flukes on line lessons when I got my fluke 117 with a coupon that was in the box.  Somethings got thru my thick skull, but not enough I guess.  Sort of lost interest with micro measuring stuff.  But never saw what you have linked to.  Thank you, I'll read thru.  

While this fluke is a "true rms"  amp's dont go high enough, imo.  But I've got a amp gauge because of starter problems in my old slant six years ago

 

Thinking about measuring starting amps in a same year as my truck, to see if amp draw is about the same being pushed thru cables.  Starters draw quite a few amps if I remember right.  

  

[Timd32]

No DVMM has high amps.

 

Need a separate Amp Clamp.

 

Most cost effective use an adapter for your 117. They put out 1mv per amp so adaper plugs into the volt slot.

 

 

Your meter has the following resolution so look up the ones that would fit nice with your meter and what you think your going to measure, so the cable fits thru the clamp.

 

 

Or get a dedicated amp clamp, which when you go to DC Amps the price kicks up a bit for a Fluke. Like double the price of your 117.

 

But ebay fixes that lots of stolen good quality meters up there, we have had atleast 8 amp clamps stolen over the years high quality stuff sold for pennies on the dollar. 4 were brand new in the box never made it to us......

 

[Mopar1973Man]

Here is the FSM version of testing...

 

[Timd32]

Yeah take away is you need to do this under loaded conditions to get the real numbers.. if you suspect a cable is bad and it looks bad, I would try to clean it up and or repair/replace, no sense trying to prove a nasty looking connection is within specs.

 

FSM is always a great first reference for this stuff.

[015point9]

Thanks everybody...

 

 Timd32...    looks like I can escape (this time) from those "amp clamps" doing a volt drop test as described above. 

WOW those "amp clamps" are more than what I paid for the meter.  

 

Mopar1973Man...I actually glanced at the FSM before posting.  But not enough it appears.

I learned something, in my mind I thought the proper way to test would be to see if, and how many amps from a known source (battery) made it to the other end. 

 

 

[Mopar1973Man]

47 minutes ago, 015point9 said:

Mopar1973Man...I actually glanced at the FSM before posting.  But not enough it appears.

I learned something, in my mind I thought the proper way to test would be to see if, and how many amps from a known source (battery) made it to the other end.

 

This is done by measuring the voltage loss at different places along the cable as in the article. Better the voltage the less amperage required as shown below.

 

Watts (load) = Volts (Supplied) x Amps (Draw)

 

So if The starter load is 8,400 watts this means 12 Volt system has to supply 700 amps. Now if you lose 0.2 or more volts that means that that has to be made up in amps. Wattage load will not change typically. 

 

8,400 Watts = 12.6 Volts x 666 Amps

 

8,400 Watts = 12 Volts x 700 Amps

 

8,400 Watts = 11.5 Volts x 730 Amps

 

As you can see the more voltage that can make it to the starter will require less amperage to do the same work. This is just an example and not actual numbers. It does show the mechanics of electricity and how a weak connection can create more amperage draw typically showing as a burnt connection. 

 

Larger the cable gauge the less voltage loss in distance.

[015point9]

Thanks for info.  So many parts of Elec is confusing to me.  Problem for me is (I think) when I do learn something, it's usually long time before I need it again.  So doesn't get cemented in my mind. 

 

 

 

 

 

[Mopar1973Man]

2 hours ago, 015point9 said:

Thanks for info.  So many parts of Elec is confusing to me.  Problem for me is (I think) when I do learn something, it's usually long time before I need it again.  So doesn't get cemented in my mind. 

 

That's why most of this stuff is in the article database so we can revisit those thing again later and renew our knowledge on different things. 

[Ed ke6bnl]

Just now, Mopar1973Man said:

 

That's why most of this stuff is in the article database so we can revisit those thing again later and renew our knowledge on different things. 

voltage drop is very helpful, to appreciate the need for voltage drop by taking the black lead and put it on the negative battery terminal and for the positive put your finger on the positive and touch the red lead to your finger and the meter will show battery voltage lets say 12.6 volt. BUT you will not be able to even light a .500 mv test light from your finger it cant carry a load. 

[Mopar1973Man]

You suppose to be on the same polarity. If your working positive both probes are on the the positive side. Never touching the negative side. Then visa versa doing negative side you never touch positive.