Battery Cut-Out Switch

[splinelube]

Awhile ago there used to be a battery cut-out swirch advertised in the MOA News. It would attach at the negative ground cable. Has anyone had experience with these and does anyone know if they are reliable and available?

[DARRYL CAINEY]

Hello RJF;
I have had a Ground Cable Switch on my 1977 R100RS for years, and yes they are reliable!
I call it my secret theft deterent and battery saver. Sorry no photos!
I found it at a heavy equipment place that services fork lift trucks. You will need this switch that can handle the heavy load amperage that the battery puts out!
It is a switch that is about 1 1/2 by 1 1/2 by 1/2 inches and has two teminal conections and a push / pull switch. You will have to make a bracket out of sheet metal to hold it into position.
I mounted it on the Right side of the bike behind the battery cover on the bolt that secures the battery box to the frame.
One side of the switch conects to the battery negative terminal and the other one to normal ground by the speedo cable. You have to use heavy cable just like the stock ground cable. I went to a battery place and had them make me two cables the right length.
When I park the bike I reach around discreatly and pull the switch.

Darryl
President Niagara BMW Riders
Ambassador BMWMOA Ontario Canada

[widebmw]

I have had one for many years, I think its the same one as Darryl described.
I have had them fail. I can't remember if they were on or off but I just carry a small nut and bolt to bypass the switch, just in case.
They are 75 amp push-pull switches. I have found them at auto parts stores.

[splinelube]

Thanks for the information. Am off to a supply house next week.

[pmdave]

Of course, pulling the switch disconnects power to your clock, GPS, etc. But it does make sense to have a big disconnect switch for maintenance, rather than continually unscrewing and wearing out the threads on the speedo cable bolt/vent/ground. If you install extra feeds off the battery, it would be important to ensure that all grounds connect to the negative battery terminal, not to the frame--otherwise a big load would try to pass through the accessory wires with the battery negative switched open.

What I have done is cut away the end of the O terminal on the lower end to make it a U. That way, you only have to loosen the bolt slightly to pull the cable off.

I believe the trailer/motorhome suppliers have large disconnect switches. Think I'll check it out.

pmdave :thumb

[Visian]

What I have done is cut away the end of the O terminal on the lower end to make it a U. That way, you only have to loosen the bolt slightly to pull the cable off.

I believe the trailer/motorhome suppliers have large disconnect switches. Think I'll check it out.


Dave -- I was told, on very good authority, that cutting your ground cable into a U is an old airhead mechanics trick that is not good for the long-term health of your charging system. All I can say is that when one of my bikes was fixed after the previous owner did this to mine, the funky charging problems I was experiencing disappeared. YMMV.

The switches are available at any R/V store. They're used to disconnect the "house" batteries when in storage to minimize the drain. They're quite beefy and can handle a motorcycle with ease.

There probably is some assembly required, as the ones I've seen are designed as part of a clamp for the battery's post.

Ian

[BradfordBenn]

Dave -- I was told, on very good authority, that cutting your ground cable into a U is an old airhead mechanics trick that is not good for the long-term health of your charging system. All I can say is that when one of my bikes was fixed after the previous owner did this to mine, the funky charging problems I was experiencing disappeared. YMMV.

The switches are available at any R/V store. They're used to disconnect the "house" batteries when in storage to minimize the drain. They're quite beefy and can handle a motorcycle with ease.

There probably is some assembly required, as the ones I've seen are designed as part of a clamp for the battery's post.

Ian

I was actually making small talk with a coworker who is an Electrical Engineer at a trade show yesterday about this topic. He is a car enthusiast, 60's Impalas. We got on the topic of battery disconnects and his comment was that as long as you have enough copper in place it is all the same. However since weight is such an issue on most vehicles, cutting the O into a U "fork" might be enough to not get enough copper in contact. His solution was to use a stouter (more copper and thicker) fork lug for his car and that solved his problem. Might work on a motorcycle? :dunno

[lkchris]

Just note that disconnecting the battery ground between the battery and the transmission does not necessarily electrically disable the bike.

Fact is, many bikes with the accessory socket will ground through the socket regardless of whether the main ground cable is disconnected at the transmission. This is enough, for example to keep the clock running. I suspect starting could be "interesting," but I'm not interesting in trying it.

Best bet is always to disconnect EVERYTHING at the battery.