Re: Noise on 12v line
You have a ground loop- the grounds for the inverter and 12v accessory outlet (maybe entire 12V system) are not properly isolated and 60Hz or a harmonic are leaking through to what should be a pure DC circuit. (All grounds are not the 'same' ground).
This will NOT be a repeatable problem car-to-car. Every one has a slightly different grounding, and the loops will be different depending on temperature, exactly where the connection was made, etc. Its also not something that can be predicted beforehand with certainty- the nonideal nature of electric circuits requires a little tweaking sometimes.
Note to the paranoid among us: THIS IS NOT A SAFETY PROBLEM!!!!! ground loops are on the order of millivolts and microamps- well below the normal signal levels present even in speaker cables.
Ground loop isolators are easy to buy for audio, TV cable, etc that have AC flowing through them. DC circuits just need to run straight back to the source- the 12V battery, here.
Securing a proper ground for DC is to do what ralph mentioned- simply run the outlet straight off the battery. In all likelihood you will not need to twist or shield this new wire too much- its not likely to pick up very much radiation form the inverter unless you run right by it. But the shielding won't hurt.
Note- this will keep the 12V outlet powered all the time- like in an older car (I assume the FEH cuts power to 12V outlets like most do today?).
Last edited by gonavy; 07-03-2006 at 07:51 AM.
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