Battery disconnect switch and ground - a stupid question.

80Zcorn

Veteran Member
Oct 10, 2016
876
Israel
I'm not an electrician but I'm trying to learn and understand most I can. Yesterday while attaching the top post battery switch I saw there's a thin bypass cable with a fuse that bypass the switch itself and keep the power to the clock, radio, etc. So as far as I understand it, the thin cable bypass the switch.
So theoretically one can still start the car even if the switch is off right?
But I do know that high amount of power require thicker cable and a thin cable will be burnt.

So if one is trying to start a car equipped with a disconnect switch and the switch is at 'off' position the power will go through the bypass thin cable but will burn it or blow up the fuse if there's any and starting the car won't be possible (fuse or not)?
 

CorkyE

Veteran Member
Lifetime Gold Member
Nov 4, 2004
11,931
Ringgold, GA
Think I have something like you're describing, a picture would be helpful. If so, no the car will not start. The starter will draw too many amps and blow the fuse. I'm using a 3 amp mini relay on my setup. So when my old forgetful azz forgets to reconnect the ground, it just trips the relay and I don't have to replace a fuse. I'll see if I can get a picture.

Edit, pic added. My battery is in trunk with fuel pump relay and EFI connections.

Batt Ground Relay.jpg
 
Last edited:

80Zcorn

Veteran Member
Oct 10, 2016
876
Israel
Exactly what I have and exactly what I thought. Too many amps and the fuse will blow up.
Thanks!
Can you please explain more about the system with the relay or its diagram so I will understand what you meant?
Btw what is the black and red cable that is attached to the negative terminal itself and bypasses the switch?
 

CorkyE

Veteran Member
Lifetime Gold Member
Nov 4, 2004
11,931
Ringgold, GA
I misspoke when I said mini relay, I meant mini circuit breaker. I got if from EvilBay, it fits into a standard fuse holder and is wired just like the fuse you described, jumpered around the battery disconnect. All the extra wires I have are for the in tank fuel pump relay, pos/neg cables direct to a ProFlo 4 EFI, and plugin for a c-tech charger.
 

jurquhart

71 Z28/RS
Feb 11, 2011
185
For what it is worth,,,I put my quick disconnect on the negative post,,, no issues that way.
 




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