Getting 1.5 ohms of resistance in 0/1 awg wire

[lostdaytomorrow 10+ year member]

Hey guys, I need some serious help. Obviously I don't know how to crimp 0/1 awg or something weird is going on. I'm putting a probe on the negative battery terminal and the other probe on my Batt. (-) to chassis and I'm getting a reading of about 1.5 ohms. I'm using the stock location of the chassis ground, and have sanded it down to bare shiny metal with 80 grit sandpaper and a star washer.

This is KLM 0/1 awg with Knu Ring terminals. I put the wire all the way into the ring terminal and hammer it down onto the wire and I can pull as hard as possible on the terminal and wire and it doesn't budge. I then wrap it in elec. tape because I don't have anything to melt the heatshrink with.

I'm getting a reading of 3.5 ohms at my ground in the back (sanded down to bare shiny metal on the body of the car), which sucks horribly for my amp, so my amp is putting out anywhere near what it should due to this.

Help me out here fellas. Do I need to get a lesson in crimping 0/1 awg or is something else off here? I'd really like to get this taken care of.

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[enzowho 10+ year member]

Using an ohm meter to measure small resistances is often hit and miss. I know when I deal with the resistances of copper wire (aka transformer windings, parasitic resistances in an inductor, etc.) I can only get good results by applying a known voltage and current, then using V=I*R to find the resistance. I really wouldn't trust your numbers.

 

[lostdaytomorrow 10+ year member]

I thought the same thing at first but I've tested multiple times with several different things and I'm sure this MM is accurate. It's not a Fluke, but it's a Craftsman and it reads the resistance on my SSD's perfectly.

 

[enzowho 10+ year member]

Even the Fluke multimeter I deal with don't work properly when you are dealing with very low resistance. For instance, last week I wound an inductor and tested the parasitic DC resistance by the above method. It was something like .5 mohms (.0005 ohms). I just tested it on my nice Fluke mm and it registered 1.29 ohms.

There is another way to figure this out too. Less accurate, but still a pretty good judge. Are you getting induced noise? If you have a ground resistance difference of >1-2 ohms between your amp and h/u, you should have horrible ground loop problems. If you aren't getting induced noise you are (a) very lucky or (b) getting an artificial resistance measurement.

 

[lostdaytomorrow 10+ year member]

I'm getting no induced noise at all man. I don't understand why the multi-meter would be off though? It measures perfectly fine on resistances from, say, the negative battery terminal to the chassis ground and the Alt. Casing to the negative terminal and things like that?

I just don't understand why the MM doesn't work when it should, that doesn't make much sense to me. We used them in engineering classes freshman and sophomore year to the same amount of resistances and they weren't top of the line or anything?

Could it just be due to a bad crimping job, or possibly my chassis just sucks at conducting current or something? It's an '06 Civic coupe.

I can understand some other problems that I'm probably not thinking about, but just writing it off to a measurement error seems like the easy way out for me and I want to get this taken care of before my Alt. goes out or my amp blows out. Thanks for your help.

 

[Death By Bass 10+ year member]

the leads of the meter probably have a 0.5 - 1.5 ohm resistance of their own...

 

[Lakota 5,000+ posts]

Whenever you but a meter into a circuit, it also becomes part of the circuit. Remember that //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[helotaxi 5,000+ posts]

Is the positive battery wire connected while you're doing this? Current flowing will totally mess up your resistance reading as well.

 

[lostdaytomorrow 10+ year member]

Really, I wasn't aware of this possibility, I'll try tomorrow with the circuit open and see if there's a difference.

If the leads had a variable resistance an ohm-meter would be useless?

If they do have resistance, it is most likely taken into account and kept constant in order to get accurate readings.

If Multimeters are so innacurate how in the world are you guys checking you connections in the Big 3 and checking your ground for least resistance?

Thanks for all the input so far guys.

 

[knukonceptz 10+ year member]

How long are the leads of this meter? Batt in front and you can reach the rear ground point to measure without adding a "jumper"? check Voltage under load and compare with whats under the hood

 

[lostdaytomorrow 10+ year member]

Of course I use a "jumper" and have also tested the resistance of it, too by just putting one probe on the negative terminal and the jumper of the other side of the (-) terminal. I'm using the Knu speaker for the jumper also, btw.

 

[lostdaytomorrow 10+ year member]

I assume from the responses that because my amp turns on fine and my V drops aren't too out of the ordinary that I will be just fine. I was just trying to optimize my electrical system and testing it using my MM. I'm assuming no one does this and I need to chill out and just assume that since my amp is working correctly, not getting hot, and no bad V drops, everything is fine.

Edit: I just realized why knu answered, and I'd like to make it 100% clear that this is in no way related to the brand of wire I am using, nor am I insuating that this wire is anything of sub-par quality. The wire is working perfectly, aside from the seeming lack of flexibility.

Just for the record.