by William from NOLA » Thu Mar 17, 2005 10:10 am
Here's an article I found that is very interesting.
Posted by PoundMuttAllways @
http://www.carsound.com/UBB/ultimatebb. ... 1;t=023338
Code: Select all
Quoted from Esoteric Audio (Street Wires)
Article Date: 1997
The current Esoteric Audio web site no longer has “White Papers” like this one.
Best Place to Ground Your System
The floor pan of a car will generally carry more current than a 1/0 cable of
any sizable length. You always want to minimize resistance by keeping all runs
as short as possible. This includes the chassis. You always want to connect
all ground cables to the same chassis part. This confuses some people, so let
me explain, If you have a truck, always run the ground cables to one of the
frame rails, or the floor pan of the cab. Do not run the ground under the hood
to the left frame rail and the ground cable in the back to the right frame rail.
Sometimes you will want to use the body as the ground. There is nothing
wrong with this, but be sure to connect to the same piece of metal in the
front as you do in the back, such as the floor pan.
There are not very many cars with a full frame anymore, so we can pretty
much exclude that here. I firmly believe that the most important points to
remember in this case are to connect to the floorpan of the car both under
the hood and in the trunk, and to remove all paint and any contaminates such
as body filler or grease from the point that the cable is connected to the
body (or frame). In fact the removal of the paint from the metal surface will
probably have as big of an effect on your voltage drop as anything. This is an
absolute must and should be done in every case without question.
I can not think of a single car that I have seen that did not have a single
large piece of sheet metal for the floor pan. Knowing this you always want to
attach your ground in the front and rear of your vehicle to this piece of metal.
The reason for this is simple: fewer connections and therefore less resistance.
I will make a way over-simple illustration here. Joe grounds his front battery
to the strut tower on his Grand Am. In the trunk, he grounds his system to
the fender well with a bolt. In both places he removes all paint and filler to be
sure he makes good contact. His ground is not as good as it could be
because he has current flow through an unknown (and possibly variable)
number of connections. Some are spot welds, some may be bolted (who
knows?) but the fact is that there are quite a few unnecessary "connections"
here. By making sure that you connect your ground points to the same body
panel, you will assure yourself of the best possible ground.
We ran a series of tests to put some actual numbers to some of the methods
used by installers . This data may surprise you.
Here is some of the data, and the outline of the procedure.
We have a lab grade machine custom built by a company in Atlanta that is
capable of measuring voltage, current and voltage drop through a circuit in
real time. It will repeat these measurements in the 500 amp range with
remarkable precision. The current level is infinitely adjustable and all of the
units (voltage, current and voltage drop) are given in real time using real
numbers based on a reference taken at the outputs. The cables that we used
for our measurements were measured before and after the test to assure
that we could "back them out" of our measurements and determine an actual
value. We used a 1985 Camaro for the test vehicle. We chose a spot in the
front of the car that an installer may choose to ground the alternator and
battery under the hood, and also one in the back of the car where someone
may ground an amplifier. We then measured the voltage drop @ 300 amps
with the cables connected using various methods.
The first two tests were done with both ends of the reference cable fastened
in the same fashion.
Test 1-- Sheet metal screw to non sanded metal- .25 volt drop
Test 2-- Sheet metal screw to sanded metal- .13 volt drop
All tests below this point were done with the front connection fastened with a
5/16 bolt through sanded metal.
Test 3-- 5/16 bolt to non sanded metal- .23volt drop
Test 4-- 5/16 bolt to sanded metal- .09 volt drop
Test 5-- 6mm existing stud painted and not sanded .24 volt drop
Test 6-- 5/16 bolt to sanded metal, on a spot welded bracket-- could only
attain 244 amps, voltage drop was approximately 5 volts.
Test 7-- 3/8 bolt to non sanded seat belt mounting nut--.15 volt drop
These tests were done using the floorpan as the ground path (except #5 and
6). Other tests using panels attached to the floorpan of the car revealed
various voltage drops. We measured drops up to 1.25 volts during the testing.
I am quite sure that this will be different for every vehicle on the road today,
but has shown that the best place to ground your system is to the floorpan,
and shown that doing the extra work to sand the paint from the metal pays a
rather large dividend.
©1997 Esoteric Audio USA
Here's an article I found that is very interesting.
Posted by PoundMuttAllways @ [url]http://www.carsound.com/UBB/ultimatebb.php?ubb=get_topic;f=1;t=023338[/url]
[code]Quoted from Esoteric Audio (Street Wires)
Article Date: 1997
The current Esoteric Audio web site no longer has “White Papers” like this one.
Best Place to Ground Your System
The floor pan of a car will generally carry more current than a 1/0 cable of
any sizable length. You always want to minimize resistance by keeping all runs
as short as possible. This includes the chassis. You always want to connect
all ground cables to the same chassis part. This confuses some people, so let
me explain, If you have a truck, always run the ground cables to one of the
frame rails, or the floor pan of the cab. Do not run the ground under the hood
to the left frame rail and the ground cable in the back to the right frame rail.
Sometimes you will want to use the body as the ground. There is nothing
wrong with this, but be sure to connect to the same piece of metal in the
front as you do in the back, such as the floor pan.
There are not very many cars with a full frame anymore, so we can pretty
much exclude that here. I firmly believe that the most important points to
remember in this case are to connect to the floorpan of the car both under
the hood and in the trunk, and to remove all paint and any contaminates such
as body filler or grease from the point that the cable is connected to the
body (or frame). In fact the removal of the paint from the metal surface will
probably have as big of an effect on your voltage drop as anything. This is an
absolute must and should be done in every case without question.
I can not think of a single car that I have seen that did not have a single
large piece of sheet metal for the floor pan. Knowing this you always want to
attach your ground in the front and rear of your vehicle to this piece of metal.
The reason for this is simple: fewer connections and therefore less resistance.
I will make a way over-simple illustration here. Joe grounds his front battery
to the strut tower on his Grand Am. In the trunk, he grounds his system to
the fender well with a bolt. In both places he removes all paint and filler to be
sure he makes good contact. His ground is not as good as it could be
because he has current flow through an unknown (and possibly variable)
number of connections. Some are spot welds, some may be bolted (who
knows?) but the fact is that there are quite a few unnecessary "connections"
here. By making sure that you connect your ground points to the same body
panel, you will assure yourself of the best possible ground.
We ran a series of tests to put some actual numbers to some of the methods
used by installers . This data may surprise you.
Here is some of the data, and the outline of the procedure.
We have a lab grade machine custom built by a company in Atlanta that is
capable of measuring voltage, current and voltage drop through a circuit in
real time. It will repeat these measurements in the 500 amp range with
remarkable precision. The current level is infinitely adjustable and all of the
units (voltage, current and voltage drop) are given in real time using real
numbers based on a reference taken at the outputs. The cables that we used
for our measurements were measured before and after the test to assure
that we could "back them out" of our measurements and determine an actual
value. We used a 1985 Camaro for the test vehicle. We chose a spot in the
front of the car that an installer may choose to ground the alternator and
battery under the hood, and also one in the back of the car where someone
may ground an amplifier. We then measured the voltage drop @ 300 amps
with the cables connected using various methods.
The first two tests were done with both ends of the reference cable fastened
in the same fashion.
Test 1-- Sheet metal screw to non sanded metal- .25 volt drop
Test 2-- Sheet metal screw to sanded metal- .13 volt drop
All tests below this point were done with the front connection fastened with a
5/16 bolt through sanded metal.
Test 3-- 5/16 bolt to non sanded metal- .23volt drop
Test 4-- 5/16 bolt to sanded metal- .09 volt drop
Test 5-- 6mm existing stud painted and not sanded .24 volt drop
Test 6-- 5/16 bolt to sanded metal, on a spot welded bracket-- could only
attain 244 amps, voltage drop was approximately 5 volts.
Test 7-- 3/8 bolt to non sanded seat belt mounting nut--.15 volt drop
These tests were done using the floorpan as the ground path (except #5 and
6). Other tests using panels attached to the floorpan of the car revealed
various voltage drops. We measured drops up to 1.25 volts during the testing.
I am quite sure that this will be different for every vehicle on the road today,
but has shown that the best place to ground your system is to the floorpan,
and shown that doing the extra work to sand the paint from the metal pays a
rather large dividend.
©1997 Esoteric Audio USA[/code]