battery disconnect switch

[Tim Ayers]

Originally Posted by glennpm

I agree, mine is on the 12V negative ground side.

Same

[paul2748]

Completely agree with you. I have had problems with two disconnects so now all I do is have a 1/2 inch wrench in the car to disconnect the battery. Never wore out a terminal either.

Originally Posted by cas3

I've never been a fan of those things. They quite often result in problems down the road a few years with bad connections in an un necessary gizmo. Just pull off the battery cable. If its clean as it should be, its an easy thing to deal with.

Those things are popular with the model A crowd as that wire harness is hot all the time. Your 47 has a fuse , no? Sorry, I am not familiar with post war stuff

[corvette8n]

+1 on the Cole-Hersee I think I bought mine off of eBay, I made sure it was an older one made in the USA.

[51504bat]

My 2 cents on which post to use for the battery disconnect. Think about when you disconnect the battery. You disconnect the ground first. That way you don't accidentally touch the hot cable to a ground source when disconnecting the hot cable with the ground still connected. JMO


Edit: but some sanctioning bodies specify that the hot side be used.


For NHRA compliance, use heavy-duty 1-gauge or 2-gauge welding cable for battery disconnect switches, especially with trunk-mounted batteries. The switch must be on the positive side, interrupting all electrical power, with the alternator wired to ensure the engine stops immediately when the switch is engaged

For Bonneville Land Speed Racing (SCTA rules), the battery disconnect switch must be installed on the positive side of the electrical system and act as a master cut-off for all electrical functions, including the alternator and ignition.

[tubman]

Originally Posted by 51504bat

My 2 cents on which post to use for the battery disconnect. Think about when you disconnect the battery. You disconnect the ground first. That way you don't accidentally touch the hot cable to a ground source when disconnecting the hot cable with the ground still connected. JMO


Edit: but some sanctioning bodies specify that the hot side be used.


For NHRA compliance, use heavy-duty 1-gauge or 2-gauge welding cable for battery disconnect switches, especially with trunk-mounted batteries. The switch must be on the positive side, interrupting all electrical power, with the alternator wired to ensure the engine stops immediately when the switch is engaged

For Bonneville Land Speed Racing (SCTA rules), the battery disconnect switch must be installed on the positive side of the electrical system and act as a master cut-off for all electrical functions, including the alternator and ignition.

I don't really understand what you are saying in your first paragraph.

I do agree with the third and fourth paragraphs.

[51504bat]

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Originally Posted by tubman

I don't really understand what you are saying in your first paragraph.

I do agree with the third and fourth paragraphs.

If you disconnect the ground first the hot post of the battery can lead to a spark if mistakenly touched to ground such as loosening the bolt on the cable end and momentarily touching the wrench to ground. Up to you which order you choose to use.