Disconnect Switch

[Caryc]

Going to pick up a battery disconnect switch for my 8N. I'm just wondering which post is best to put it on?

 

[R Geiger]

(quoted from post at 04:55:39 12/06/12) Going to pick up a battery disconnect switch for my 8N. I'm just wondering which post is best to put it on?

I would think it would depend on if it is 6 or 12 volts. 6 volts I would put it on the neg post and 12 on the post post.

 

[Mike Groom]

It should be on the power side of the battery,not the ground side.

 

[Caryc]

(quoted from post at 13:54:47 12/05/12) It should be on the power side of the battery,not the ground side.

That's kind of what I figured. It's 12 volt neg ground.

Thanks guys

 

[El Toro]

The military used this type master switch connected between the battery's neg post and a good ground on the tractor. That will isolate the battery from being grounded. Hal

 

[old]

If you look at most service manuals when doing any thing to an engine they tell you to pull the - battery cable so that is where I would put it since no matter what you can never ground the battery if something odd happens. That is why it is done that way by the service manual

 

[Caryc]

(quoted from post at 15:34:27 12/05/12) If you look at most service manuals when doing any thing to an engine they tell you to pull the - battery cable so that is where I would put it since no matter what you can never ground the battery if something odd happens. That is why it is done that way by the service manual

The switch I'm going to get is from Harbor Freight and does go on a battery post. But which one? One here says positive and another says negative.

I'm leaning towards the positive post myself.

 

[Bob Harvey]

Dumb as this may sound, it doesn't matter which post you choose, as long as the battery is DISCONNECTED.

 

[russb wa]

Yep, no way the battery is going to know the difference.

 

[JMOR]

(quoted from post at 19:38:45 12/05/12) Yep, no way the battery is going to know the difference.

s far as interrupting the electrical circuit, true, it makes no difference. Consider this: when removing or installing a battery, always disconnect the grounded terminal first and connect the grounded terminal last. Why? Because if your wrench happens to bridge the battery post to chassis of the grounded terminal as you tighten the clamp, nothing happens since the wrench is simple parallel with the ground strap. BUT if you had connected the ground first and then have the wrench bridge the hot battery terminal over to chassis as you tightened the hot clamp, you will have fireworks! So, with your switch, if installed in the hot lead, then any object bridging the hot terminal or hot switch parts over to chassis will result in fireworks even with switch off (perhaps as you do maintenance on the tractor). Now, if you were to install it in the grounded lead, then a wrench bridging hot to chassis does nothing (switch off) AND bridging from the switch parts or grounded terminal will simply connect the battery......no fireworks.

***After thought. Now that I built a case for placing switch in the grounded cable, here is a good reason to place it in the hot cable, IF YOU EVER OPERATE THE SWITCH WITH ENGINE RUNNING: disconnecting ground while running is a good way to damage electronic components, etc. if using an alternator (depending on the specific alt or specific VR, the voltages can go very, very high).......with old DC generators, people debate that case forever, but it used to be common practice without harm.

Pick your poison!

 

[GB in MT.]

(quoted from post at 17:59:31 12/05/12)

(quoted from post at 19:38:45 12/05/12) Yep, no way the battery is going to know the difference.

s far as interrupting the electrical circuit, true, it makes no difference. Consider this: when removing or installing a battery, always disconnect the grounded terminal first and connect the grounded terminal last. Why? Because if your wrench happens to bridge the battery post to chassis of the grounded terminal as you tighten the clamp, nothing happens since the wrench is simple parallel with the ground strap. BUT if you had connected the ground first and then have the wrench bridge the hot battery terminal over to chassis as you tightened the hot clamp, you will have fireworks! So, with your switch, if installed in the hot lead, then any object bridging the hot terminal or hot switch parts over to chassis will result in fireworks even with switch off (perhaps as you do maintenance on the tractor). Now, if you were to install it in the grounded lead, then a wrench bridging hot to chassis does nothing (switch off) AND bridging from the switch parts or grounded terminal will simply connect the battery......no fireworks.

b:902da55199][i:902da55199]

Not to mention the fact that,.....If he is buying the "Green Topped" discon nect, The only way to make sure it STAYS disconnected,....is to remove the Green top completely, and move the cable away from the battery post.
Should read the buyers comments.....before buying!!!!
JMHO....I would buy the "Heavy Duty" disconnect switch.......only four $$'s more!!!!!!!!!....AND, it is a switch!!!!!!!!

Gary :roll: [/i:902da55199][/b:902da55199]

 

[Caryc]

(quoted from post at 17:15:55 12/05/12)

(quoted from post at 17:59:31 12/05/12)

(quoted from post at 19:38:45 12/05/12) Yep, no way the battery is going to know the difference.

s far as interrupting the electrical circuit, true, it makes no difference. Consider this: when removing or installing a battery, always disconnect the grounded terminal first and connect the grounded terminal last. Why? Because if your wrench happens to bridge the battery post to chassis of the grounded terminal as you tighten the clamp, nothing happens since the wrench is simple parallel with the ground strap. BUT if you had connected the ground first and then have the wrench bridge the hot battery terminal over to chassis as you tightened the hot clamp, you will have fireworks! So, with your switch, if installed in the hot lead, then any object bridging the hot terminal or hot switch parts over to chassis will result in fireworks even with switch off (perhaps as you do maintenance on the tractor). Now, if you were to install it in the grounded lead, then a wrench bridging hot to chassis does nothing (switch off) AND bridging from the switch parts or grounded terminal will simply connect the battery......no fireworks.

b:ad2a81f7bd][i:ad2a81f7bd]

Not to mention the fact that,.....If he is buying the "Green Topped" discon nect, The only way to make sure it STAYS disconnected,....is to remove the Green top completely, and move the cable away from the battery post.
Should read the buyers comments.....before buying!!!!
JMHO....I would buy the "Heavy Duty" disconnect switch.......only four $$'s more!!!!!!!!!....AND, it is a switch!!!!!!!!

Gary :roll: [/i:ad2a81f7bd][/b:ad2a81f7bd]

I saw that were two and I had already planned to buy the more expensive one.

 

[HCooke]

Why not just disconnect the ground each time you
park it for a long term?

 

[Caryc]

(quoted from post at 17:33:30 12/05/12) Why not just disconnect the ground each time you
park it for a long term?

Because a switch is simply easier.

 

[Caryc]

Well crap, I just looked on Harbor Freights site and now they only list that green knobbed one. I guess they no longer carry the other one.

Guess I'll have to see what the parts stores have.

 

[Bob Harvey]

Oh Man !, Just what we need , another quandry !
My brane already hurts (probly from too many beverages yesterday in the city-ugh). We need a definitive answer-mine is; "just take the freakin' cables off BOTH terminals when you are messing around". The trick is; you get to see how much corrosion is there ( I ALWAYS use the brush cleaner on cables and battery after disconnection and slather the suckers up with grease, Pork belly, Bear, Elk or just the perverts fave, Vasoline-don't matter!)

 

[old]

As I said if you think about it. If you go with the ground then no matter what there is no way to short out the system but if you go with the other then you can in fact short something out. That is why if you look in most any service manual it will say disconnect the ground wire before working on the car/truck/tractor and the reason if because if you say drop a wrench on the battery the only way you can short things out is if it drops across both battery posts but if dropped so it hit the frame and the post no short out and no sparks

 

[russb wa]

Humn, I wasn't thinking of those issues. I may
have in the past thought about the ground
last/first connect/disconnect, specially if the
circumstances made me concerned, I don't recall.
You made a good point and I appreciate the clearer
thinking. Thanks, I needed that!

 

[JMOR]

More than welcome!

 

[old]

Ya the switch maybe simpler but then you add another part to the system that can/will go bad. I know my dad did the disconnect switch to a machine years ago and I had to fight it all the time because it would maybe work as it should but most of the time would cause more trouble then worth and I told him pull the battery cable off

 

[carpetfarmer]

As to which side to put the switch, I put mine on the hot side, between the battery and the starter switch as seen in the picture. I used a length of string to attach the ignition key and the disconnect key toghether, in part so they wouldn"t be lost, and also as a reminder.

To cover the switch and protect it from the elements when the tractor is sitting, I used a chair leg tip...perfect fit.

 

[jokester]

[b:0839152d8f]WHY?[/b:0839152d8f] If Henry had thought it was needed, it would have been there from the factory. Why?????

 

[Caryc]

(quoted from post at 20:11:49 12/05/12)
[b:7242759d85]WHY?[/b:7242759d85] If Henry had thought it was needed, it would have been there from the factory. Why?????

Because a disconnected battery will discharge slower than a connected one.

 

[jokester]

(quoted from post at 04:17:17 12/06/12)

(quoted from post at 20:11:49 12/05/12)
[b:d840792bfc]WHY?[/b:d840792bfc] If Henry had thought it was needed, it would have been there from the factory. Why?????

Because a disconnected battery will discharge slower than a connected one.

Again, I say why??????? On an original 9/2/8N Ford tractor there is no , I repeat NO drain on a connected battery that would possibly make it discharge faster than a not-connected battery! Tell the world what it is for Christ sake!

 

[Caryc]

(quoted from post at 20:26:50 12/05/12)

(quoted from post at 04:17:17 12/06/12)

(quoted from post at 20:11:49 12/05/12)
[b:45692dbddc]WHY?[/b:45692dbddc] If Henry had thought it was needed, it would have been there from the factory. Why?????

Because a disconnected battery will discharge slower than a connected one.

Again, I say why??????? On an original 9/2/8N Ford tractor there is no , I repeat NO drain on a connected battery that would possibly make it discharge faster than a not-connected battery! Tell the world what it is for Christ sake!

Because battery disconnect switches give me a warm and fuzzy feeling. Is that good enough for you? Shall I write that out and get it notarized for you?

My great great great grandfathers life was also saved by a battery disconnect switch in the war of 1812.

And if none of those satisfy you, because it's my tractor and if I want to put one on it, I will. Nanner...Nanner...Nanner

 

[jokester]

(quoted from post at 04:35:15 12/06/12)

(quoted from post at 20:26:50 12/05/12)

(quoted from post at 04:17:17 12/06/12)

(quoted from post at 20:11:49 12/05/12)
[b:91a62934a4]WHY?[/b:91a62934a4] If Henry had thought it was needed, it would have been there from the factory. Why?????

Because a disconnected battery will discharge slower than a connected one.

Again, I say why??????? On an original 9/2/8N Ford tractor there is no , I repeat NO drain on a connected battery that would possibly make it discharge faster than a not-connected battery! Tell the world what it is for Christ sake!

Because battery disconnect switches give me a warm and fuzzy feeling. Is that good enough for you? Shall I write that out and get it notarized for you?

My great great great grandfathers life was also saved by a battery disconnect switch in the war of 1812.

lright! I do like honesty! :wink:

 

[Anonymous-0]

According to HF on line catalog they still have the other switch. It is called "Heavy Duty Battery Cutoff Switch" SKU 66789 $9.99.

Hope that helps.

 

[Caryc]

(quoted from post at 21:50:24 12/05/12) According to HF on line catalog they still have the other switch. It is called "Heavy Duty Battery Cutoff Switch" SKU 66789 $9.99.

Hope that helps.

I went to their website and ran a search on "Battery Disconnect Switch" and that cheaper green one was the only one that came up. Thanks for the number.

 

[ASEguy]

Yep. Always disconnect the ground first and hook it up last. Standard practice.

 

[55deere70]

A battery disconnect switch is one of the best things you can install on a piece of equipment. Why? Because if you have a battery cable or other hot wire chafe through, or any other unforseeable thing happen, you can switch off the source quickly and safely before the fire gets too big. I have seen more than one fire because of a chafed wire an it's not easy to put out if you can't disconnect the battery. Can get very ugly quick. We have them on almost every piece of equipment, we use the HD Pollak switches, not those cheap battery terminal screw type.

 

[W_B]

I put the knife switch type on my Ford Expedition since it would be parked for a time and lots of drain from all the electronic crap on it. Instructions said to put it on the positive terminal. Got it at the local auto parts store for about $12.

 

[gatchelguy]

Carpetfarmer's excellent pics show THE reason for a disconnect switch. When the genny cutout points stick the battery will drain and the genny might fry.

 

[Greg 2N (TX)]

Wow Wow Wow,

What A Can Of Worms Huh?
What A Can Of Worms Huh?
What A Can Of Worms Huh?

Look, do as you will, be strong, hang in there.

All I have to say is this;

Be careful not to disconnect while engine running.
If so, it is a "Load Dump!"

A load dump (no battery load for alternator) means alternator voltage will spike up to about 60 volts or more to make some solid state crispy critters.

I know you probably know this already, but just wanted to mention it.

Regards,

Happy Switching (engine off)

Merry Christmas too,

Greg

 

[Bob Harvey]

Just to add to the 'debate'. Back in the day I raced sports cars and it was mandatory to have a battery 'kill' switch - pos terminal. IIRC

 

[JMOR]

(quoted from post at 21:14:01 12/06/12) Just to add to the 'debate'. Back in the day I raced sports cars and it was mandatory to have a battery 'kill' switch - pos terminal. IIRC

CCA & others require it in hot terminal because its purpose is to kill the engine in a crash-emergency situation. They also test then during safety inspection, so............what happens to the electronics???? Further more, when they were old DC generators, they should have kept on running anyway!??

 

[Caryc]

(quoted from post at 11:29:21 12/06/12) Wow Wow Wow,

What A Can Of Worms Huh?
What A Can Of Worms Huh?
What A Can Of Worms Huh?

Look, do as you will, be strong, hang in there.

All I have to say is this;

Be careful not to disconnect while engine running.
If so, it is a "Load Dump!"

[b:6c2b653dee]A load dump (no battery load for alternator) means alternator voltage will spike up to about 60 volts or more to make some solid state crispy critters.[/b:6c2b653dee]

I know you probably know this already, but just wanted to mention it.

Regards,

Happy Switching (engine off)

Merry Christmas too,

Greg

Are you saying this happens when you turn off the engine with the key, then use the disconnect switch?

Or are you saying this will happen if you use that disconnect switch with the engine running?

 

[Royse]

Cary, he was saying that happens if you disconnect it while the engine is running.
"Be careful not to disconnect while engine running."
If the alternator is not spinning there will be no output.

 

[Caryc]

(quoted from post at 19:01:44 12/06/12) Cary, he was saying that happens if you disconnect it while the engine is running.
"Be careful not to disconnect while engine running."
If the alternator is not spinning there will be no output.

Thank you. I had not intention of using the disconnect while the engine is running, only when the tractor is parked and going to sit a while.

 

[Greg 2N (TX)]

JMOR,

I would suspect that those applications have some sort of Load Dump protection in one form or another.

All I know is with something like the 10-SI, I'd have Zero faith in its Load Dump protective ability.

Well.... lets say the poor guy has the beloved Pertronix EI....boy I don't think it would like it either.

Regards,

Greg
Load Dump App Note