Numbers for 4 and 00 gage (archive)

4 guage is too thin. I used 00 guage. Look around at welding supply shops, I found a 15 ft length for $1.50 a foot. I woud say min thickness would be 1 or 2 guage.

4 gage has .253 ohms/1000ft
00 gage has .0795 ohms/1000ft

Use 15ft and at 210 amps to starter
4 gage Volts =I*R
=210*(.253*(15/1000))
=0.8 volts drop in the line when starting
00 gage
=210*(.0795*(15/1000))
=0.25 volts drop in the line when sarting
A battery voltage drops to about 10 volts under starting.

4 gage 10 -.8 = 9.2 volts
00 10 - 0.25 = 9.75 volts

Power to start car W=V*I
4 gage = 9.2*210 = 1932 watts
00 gage = 9.75*210 = 2048 watts

Coil voltage
nominal 15000 volts at 10 volts
4 gage 15000*(9.2/10)= 13800 volts
00 gage 15000*(9.75/10) = 14625 volts

PS I have 000 welding cable in my instalation.

Follow Ups:

Re: Numbers for 4 and 00 gage 7AO 13:53 9/03/2001 (2)
- Ignition beyond what is needed john 70 1602 17:00 9/03/2001 (1)
  - Huh?? Large wire is for starter motor, your coil John N 20:06 9/03/2001 (0)

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