model a battery disconnect question

E

Epetek1

Senior Member
does it make a difference whether you use the positive or negative post to attach a disconnect. Also the usual imported ones are troublesome. I spent a few hours when my car wouldn't start before i found out that the connections are hard to tighten properly. Any hints or ideas appreciated.
Thanks Pete also best email address for me epetek1@gmail.com
 
Not knowing whether your car is 6 volt +ve earth (ground) or 12 volt -ve earth, I will not say +ve or -ve, just active or earth side of the battery. It is best to put the cutout on the earth side - that is, between the battery and your earth connection at the chassis.
That way, when it is turned off, everything is dead and no short circuit to earth can cause a problem.
 
I agree with Synchro909 the ground cable should have the switch in line. I mounted my switch between the front seats on my 29 Tudor. Very easy to turn the switch on or off.
 
DBrer said:
I agree with Synchro909 the ground cable should have the switch in line. I mounted my switch between the front seats on my 29 Tudor. Very easy to turn the switch on or off.
Click to expand...

In my Tudor, it is mounted on the cross member between the seats. To turn it on or off, I just poke my finger through a slot in the carpet. It's nearly invisible.
 
This is where the switch is in my Coupe:

picture.php
 
If the ground cable has the disconnect switch, and something with a hot lead in the car sorts to ground, then current will flow from the battery regardless of the disconnect. In my opinion, a disconnect switch is best put into the battery cable going to the starter.
 
Bob Bidonde said:
If the ground cable has the disconnect switch, and something with a hot lead in the car sorts to ground, then current will flow from the battery regardless of the disconnect. In my opinion, a disconnect switch is best put into the battery cable going to the starter.
Click to expand...



Not sure I understand, if the ground battery post is disconnected by the switch, how can there be any current flow?
 
Bob Bidonde said:
If the ground cable has the disconnect switch, and something with a hot lead in the car sorts to ground, then current will flow from the battery regardless of the disconnect. In my opinion, a disconnect switch is best put into the battery cable going to the starter.
Click to expand...

With no ground on the battery there will be no current flow from the hot side of the battery. The vehicle frame has no continuity to the ground lug on the battery with the disconnect switch on the the ground side and the switch off (open).
 
I prefer interrupting the ground side of the battery, + side, for several reasons.
It's generally easier to deal with the ground cable to chassis. Also if you
interrupt the hot side of the battery and the disconnect switch shorts to ground
you have instant full blown short. Had a couple of farm tractors do that. Thats
how i know. Always buy a heavy duty disconnect switch. Lots of Amps
flowing through that switch when starter is engaged. Lastly, when you put the disconnect on the hot side, your creating two more connection points in an
area that is prone to water and road debris (more shorts).
 
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