Finding good ground to prevent Ground Loop
Today I was working on my car audio system and decided to use a meter to measure all the different ground points in my car. I put my meter into OHMs mode and started measuring between the ground points in my car and the negative post of the battery.
First I measured the ground point of my headunit and it shows 0.3 ohm.
Then I measured the ground point of the OPUS and power inverter which shows 0.4 ohm.
I also measured a few other factory ground points and they are all around 0.3 to 0.5 ohm.
Are my ground points good enough to not have any ground loop?
Lastly I compared the resistence between the car's frame metal with paint and without paint. The difference is HUGE. This shows that when making a ground it is VERY important that the painted is being sanded off.