There has been several discussions regarding the best practice with regards
to grounding devices and batteries in vehicles.

Some recommend that the device is grounded as close as possible to the
device to the chassis.

Other suggest running a negative lead all the back to the battery or to the
battery earth point.

I once considered it best to run both a negative and positive lead all the
way to the battery.  However, over time I have been convinced that using
the chassis provides a superior return as it will offer less resistance and
reduce ground loops. (Reduce ground loops as in the case where the chassis
of the device comes into electrical contact with the chassis of the vehicle
and there is also a negative return lead to the battery).

Justin
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