Grounds...

[helotaxi 5,000+ posts]

You'll never reach 0. Most likely you'll see between 1 and 4 ohms on a good connection.

You should have less than .5 ohms at a good ground spot.

1-4 ohms is an absolutely terrible ground. If your ground had 1 ohm of resistance between it and the battery negative post you would lose a volt of potential for every amp that your amplifier drew. Pull more than 4 A and the amp will go into protection. 0.5 ohms isn't really any better. 8A to shut down the amp. 15ft of 1/0 has a resistance of 0.00144 ohms. That is the kind of ground resistance that you should be looking for. If you can directly measure it with a standard DMM, it's too high.

 

[lostdaytomorrow 10+ year member]

1-4 ohms is an absolutely terrible ground. If your ground had 1 ohm of resistance between it and the battery negative post you would lose a volt of potential for every amp that your amplifier drew. Pull more than 4 A and the amp will go into protection. 0.5 ohms isn't really any better. 8A to shut down the amp. 15ft of 1/0 has a resistance of 0.00144 ohms. That is the kind of ground resistance that you should be looking for. If you can directly measure it with a standard DMM, it's too high.

Maybe my DMM isn't accurate enough then... It's a craftman's not a Fluke.

 

[helotaxi 5,000+ posts]

My point is that very few DMMs are able to measure the ground path resistance of a good ground. If you are measuring with a standard consumer grade DMM (which is more than adequate for pretty much any real task you would encounter) and get a measurable amount of resistance, it's too high. What you are looking for in a ground is "below measurable limits." A DMM that can actually measure the extremely small resistance of a good ground is going to run you close to a grand and is way beyond what the car audio enthusiast has need for.

 

[IgnoreMe 5,000+ posts]

stick one probe on the batt Neg terninal, then stick the other probe on the area you wish to ground and see what kinda resistance you have.

this is the best way to go trying to measure resistance, however do not stick it on the negitive battery terminal.

you need to power down and isolate. meaning you need to disconnect your front battery ground and then attach the dmm leads to that ground cable and your potential ground. leaving it connected to the battery is not the right way to measure resistance.

no power through the circuit your trying to test.

 

[bumpincrv 10+ year member]

this is the best way to go trying to measure resistance, however do not stick it on the negitive battery terminal.
you need to power down and isolate. meaning you need to disconnect your front battery ground and then attach the dmm leads to that ground cable and your potential ground. leaving it connected to the battery is not the right way to measure resistance.

no power through the circuit your trying to test.

Excatly and that will also help in not blowing fuses in the dmm the ohm meter is meant to test with NO power circuts if it sees enough power (which isnt much) you will blow a somewhat pricey fuse