VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt BATTERY DISCONNECT SWITCH

I would like to hear some comments on some of the battery disconnect switches that are avialable on the market. I have tried the one that you screw the knob down when you want juice to the car and have not had any good luck with It. I have tried three new ones and when I tighten the knob, Trying to start the car, It is a hit and miss getting enough juice to the starter to turn the engine over. I take the switch off and leave the battery hooked up all the time and never have a problem starting the car. I know there must be several different type disconnect switches avialable. Thanks :) :)

Don,
I've used one of those screw type switches for about a year on my '46 pickup and haven't had any problems at all. Mine is connected to the neg battery terminal if that makes a difference. I did spend some time scraping the socket on the switch that mates with the terminal to make sure it had good contact. I also made sure the two surfaces of the switch itself were clean and made good contact. Don't know if this helps.

Don,
I've used one like you mention (cost about $3.00 at flea markets and has a green knob) on my 31 Coupe for about 4 years and never had a problem with it. It should be mounted on the negative terminal.

Thanks, Peter and Doug for your reply about the disconnect switch. The one I have, Also has the green knob that you tighten down and It Is on the negative ground post. I have not had any good luck with them. I have the battery posts clean and everything bolted tight and still get a hit and a miss useing them. I would like to find some other ones that are on the market. I know other guys who have the same one with the green knob that you tighten down and a couple of the guys have the same problem as I have. I now have the battery cables hooked up all the time, but I really do not like to do that, Even with the new wiring I have In the car.

The first thing I did when I bought the 52 was buy a similar disconnect switch. I have had no problems with it but have found that the under side of the terminal half of the switch needs the same care and feeding as the posts them selves. If you are not careful when connecting the switch it is possible to have an air gap and thus reduced contact. Since the problem appears to be intermittent with the switch in place then it would appear to be an incomplete connection.

Seems everyone has commented that they have mounted their "green knob screw down" disconnect switch to the negetive battery post. Does it matter if you have it on the positive post instead?? Any hazards?? :confused:

31 Chevy Guy: I can't think of any electrical reason for installing the battery cut-off switch to the negative terminal, except the terminals on the top post batterys are of slightly different diameters (the negative post is smaller) and perhaps the switches are made to fit on the smaller post. I have purchased several of these switches (green knobbed ones) over the years, to mount on every antique vehicle (negative post) I've ever owned and have never had a problem with any one of them.

Interestingly, I just checked and found a lever action disconnect switch that I bought and never installed. The instructions with this switch call for the switch to be installed between the POSITIVE post of the battery and the starter switch. :confused:

-Bob

I have the same switch installed on my 12 volt cars only.Installed on positive cable with no problems.Nothing on the 6 volt cars as they just get warm and smoke a little. :cool2:

An additional comment on mounting these "Green Knob" switches, mine came with instructions to mount to the negative post. It would take a little effort with a big hammer to get one mounted on the positive post.

chevy,

I have a few of the switches installed (6 & 12 volt vehicles) and agree with all the previous postings about it being made to fit the negative post...

one thing that I'd like to add is that mine came with not only the required taper on the inside of the clamp to properly mate with the post, but also had a slight taper on the outside of the clamp where the binder bolt head and nut contacted...I think this is to allow an easier release from their mold at the foundry...

perhaps if the binder bolt isn't tightened enough, the tapered clamp may not have uniform contact with the battery post...I filed the binder bolt bosses before I installed and have not had any problems...could this be the problem with your intermittent switch?..

I also filed the switch post where the cable attached, because mine were crudely made and weren't uniformly round...on a 6 volt system, every bit of ground path contact matters...

epi

My bulldozer also has one of those battery disconnect switches with the green knob that I installed 5 years ago. The switch is installed on the negative battery post and the bulldozer has been sitting out for 5 years and the battery disconnect hasn't failed yet! :eek:

Yup....another one! I'm one of those "green Knob / neg. terminal" guys also. Chock up another....

Thanks for all the replys. I took the starter out of my car today and bench tested It and the rebuild by skip geear Is great. The one thing that I think has given me all the problems trying to start the car Is, The STARTER SWITCH. When you step on the starter button and push the two brass contacts together Inside the starter switch cover, One of them was twisted to one side and about one sixth of that brass botton was making contact with the other one and was putting almost no juice to the starter. Now I hope when I put the starter back In and hopefully everything will work right, Then I can use my green knob disconnect switch. We shall see? :) :) :)

Never bought one... couldn't figure out why I needed one. Always figured that if they were good to have, then good 'ol Louis C. would have installed one for me at the factory.

I don't imagine that vendors make a lot of money when they sell these, but, by golly, they sure do sell a lot of them... so I guess that eventually it adds up. <img border="0" alt="[twix]" title="" src="graemlins/twix.gif" />

Seriously, if anyone can explain the value of these, I'd like to know. Does it truly prevent your battery from running down? or does it prevent corrosion? or what? Inquiring minds want to know.

Hey Billie Boy Barker, I think you may want them on your car to save the new garage from burning down, But what the heck, IF ya dont get the cars restored and running, Ya wont need them little green giant turn em down disconnect switches. Oh yes, you have that running tractor, So you could really use one at that.WOW :arrow: :arrow:

I like the fire prevention approach to green knobbed switches, the wiring in the 52 is original, not the best there is and I feel pretty secure that there will be no unwanted fire while the car is stored. Could happen on the road but at least not in the attached garage when I am in town ordering parts from NAPA!

Many years ago I opened my garage door and there was a very acrid smell....burned wire insulation. The wire from the ignition switch to the coil had fried with every bit of the wire covering burned off of it, due to a faulty ignition switch, as I remember. The garage was attached to my house and, if the red-hot wire had touched the wrong stuff, it could have burned my car, garage, & house down, not to mention possibly killing my family. I've used battery shut-off switches on every old car I've owned, since then. Cheap insurance, when you consider the possible consequences!!

Also, if you have a clock running, with the ignition turned off, it will keep your battery from running down during long periods of storage. They do sell a shut-off switch with a fused (3-amp ?) wire to allow the clock to run, but blowing the fuse in case of a short, for priods of less lengthly storage.

-Bob

There we go.

Down under there is a remote mounted switch that is connected between teh battery and starter or battery and frame. It is capable of handling 24 volt truck systems on caterpillar 3208 and I have seen them on bulldozers as well.
! of the advantages of these units is when it is turned off the key can be removed making unauthorized use more difficult