The Hollister Road Company
There seems to be a popular belief that the larger the wire to the device the better it is, but thats not necessarily so. There is a formula that can help you determine what gage you need and how long the wires needs to be before going up in gage. I've seen ads for relay kits that say if you used anything less that 10 gage on the powered device that you can loose up to 1.5 volts which is true if you have a 14 gage wire, 12 volt system, the device pulls 25 amps and the wire is 25 feet long. I've not seen many cooling fans that pull 25 amps and you place them 25 feet from the battery.
In the case of a remote battery it can actualy have a negative effect on the starter if the wire gage is to big. If you need a circuit to shut off when the switch is opened, to large a wire can actually store voltage and continue to power the device until the voltage is depeleted. Now this may be only miliseconds to 1 or 2 second at most but its enough to trash a perfectly good starter drive and flywheel ring gear.
With properly matched devices and circuits you can save a good deal of money and stilll have properly functioning fans or pumps that don't drop voltage. Below is a basic wire selection table for the minimum gage per foot.
WIRE GAUGE SELECTION TABLE
Circuit Amperes
Circuit Watts
Wire gauge (for length in feet)
6V
12V
6V
12V
3'
5'
7'
10'
15'
20'
25'
0 to 2.5
0 to 5
15
30
18
18
18
18
18
18
18
3.0
6
18
36
18
18
18
18
18
18
16
3.5
7
21
42
18
18
18
18
18
18
16
4.0
8
24
48
18
18
18
18
18
16
16
5.0
10
30
60
18
18
18
18
16
16
16
5.5
11
33
66
18
18
18
18
16
16
14
6.0
12
36
72
18
18
18
18
16
16
14
7.5
15
45
90
18
18
18
18
14
14
12
9.0
18
54
108
18
18
16
16
14
14
12
10
20
60
120
18
18
16
16
14
12
10
11
22
66
132
18
18
16
16
12
12
10
12
24
72
144
18
18
16
16
12
12
10
15
30
90
180
18
16
16
14
10
10
10
20
40
120
240
18
16
14
12
10
10
8
25
50
150
300
16
14
12
12
10
10
8
50
100
300
600
12
12
10
10
6
6
4
75
150
450
900
10
10
8
8
4
4
2
100
200
600
1200
10
8
8
6
4
4
There is also a very good calculator at this site with good expliantions of voltage drop. http://www.stealth316.com/2-wire-resistance.htm
