Remote battery isolator (push button kill switch)

[rsportvolvo]

Is anyone using a remote battery isolator with a push button kill switch? Armtech manufactures one that Truechoice used to distribute.

http://www.armtech.co.uk/

It is available directly from Armtech or through Demon Tweeks. There are several other manufacturers (see link)

http://www.demon-tweeks.co.uk/produc...04&tlgrp=MS005

I know that BMW Motorsport uses an aircraft type switch on the cowl, but they also use an in house power control module that replaces convential relays. Similar to the OBR unit used by Porsche Motorsport.

http://www.obr.uk.com/

I plan on checking with IS Motorsport and Sakata as they make racing harnesses.

I want a clean installation and I prefer not to run extra heavy gauge wire to a conventional kill switch.

[JoshS]

I'm not convinced that the rules would allow such a thing, I'd contact a scrutineer first.

"The master switch shall be installed directly in either battery cable and shall cut all electrical circuits but not an on-board fire system."

I'm not convinced that a remote relay is the switch ...

[Duc]

Do not see why it would not be a switch, it just happens to be a remote one.

Here is one of the manufacture site: CarTek seems that they are FIA approved. Have you found one state side?

[seckerich]

If all it does is cut power then actuation is not specified. Smart choice. A relay is just an electrically operated switch. We used these on some of the GA cars and they are very good.

[JoshS]

I'm not saying it's illegal, I'm just saying that because it's quite different from the norm, some scrutineers might have trouble with it. I'd have liked to use one of those if I'd known about them. But before I did it, I'd check with my region's chief of tech, just to make sure it would pass ...

[Rabbit07]

In my car builds I use a relay just as you have described with a two toggles wired in series to ground to control them. One switch is for the driver the other is for the corner workers. Totally legal and much safer than running 20 extra feet of battery cable.

[rsportvolvo]

I'm not saying it's illegal, I'm just saying that because it's quite different from the norm, some scrutineers might have trouble with it. I'd have liked to use one of those if I'd known about them. But before I did it, I'd check with my region's chief of tech, just to make sure it would pass ...

I'm afraid I didn't see a luddite clause in the GCR (SCCA = Luddite at times). Is it my responsibility to educate scrutineers?

The relay/remote switch is intrisically safer than running "hot" battery lines into the cockpit and cowl. I just want to make sure I'm learning from other's experience with this setup.

Do not see why it would not be a switch, it just happens to be a remote one.

Here is one of the manufacture site: CarTek seems that they are FIA approved. Have you found one state side?

I haven't found a CarTek dealer stateside. I can buy directly from Armtech. I'll most likely purchase the Armtech battery isolator as I also need a rev limiter (using stock ignition).

In my car builds I use a relay just as you have described with a two toggles wired in series to ground to control them. One switch is for the driver the other is for the corner workers. Totally legal and much safer than running 20 extra feet of battery cable.

Thanks for the info.

[Greg Amy]

I'm afraid I didn't see a luddite clause in the GCR (SCCA = Luddite at times).

Mebbe.

A nifty idea. But, the rule (GCR 9.3.33) states:

The master switch shall be installed directly in either battery cable and shall cut all electrical circuits but not an on-board fire system.

Since you're required to cut "all" electrical circuits (except fire system) how will you legally power the electrical system that controls this remote relay/button? You can use a locking relay system to disconnect, but without that low current system (note that there's no dispensation for "except low current circuits") how are you going to re-power it each time?

Note I'm not commenting on the technical merits or suitability, I'm simply commenting on the legality vis-a-vis the "Luddite" regulations...

Then, of course, there's the "new" factor, in regards to your being trapped in your car, with a pool of gasoline slowly forming, and a corner worker has to A) discover your "kill switch", quickly figure out how to use it, and C) activate it while you hope that this low-current circuit is low-current enough (whereas the traditional "kill" switches are sealed.)

Just sayin'...

Sometimes tried-and-true is, well, tried-and-true. - GA

[JoshS]

I'm afraid I didn't see a luddite clause in the GCR (SCCA = Luddite at times). Is it my responsibility to educate scrutineers?

The relay/remote switch is intrisically safer than running "hot" battery lines into the cockpit and cowl. I just want to make sure I'm learning from other's experience with this setup.

I don't disagree that it's probably both safer and cleaner. Unfortunately, that doesn't mean that when you show up at your first race and go through tech, that they won't send you home. I'm just saying that it's a good idea to confirm that such an event will not happen. Asking a bunch of other racers on the internet what your local scrutineer would say doesn't seem like a good idea. Just ask the scrutineer!

[Rabbit07]

Mebbe.

A nifty idea. But, the rule (GCR 9.3.33) states:

The master switch shall be installed directly in either battery cable and shall cut all electrical circuits but not an on-board fire system.

Since you're required to cut "all" electrical circuits (except fire system) how will you legally power the electrical system that controls this remote relay/button? You can use a locking relay system to disconnect, but without that low current system (note that there's no dispensation for "except low current circuits") how are you going to re-power it each time?

Note I'm not commenting on the technical merits or suitability, I'm simply commenting on the legality vis-a-vis the "Luddite" regulations...

Then, of course, there's the "new" factor, in regards to your being trapped in your car, with a pool of gasoline slowly forming, and a corner worker has to A) discover your "kill switch", quickly figure out how to use it, and C) activate it while you hope that this low-current circuit is low-current enough (whereas the traditional "kill" switches are sealed.)

Just sayin'...

Sometimes tried-and-true is, well, tried-and-true. - GA

Greg, it's quite simple, the power for the relay is ran off the always hot side B+. You are disconnecting it when the switch is in the off position. With the low current side open when the relay is open there is no flow of electrons past the soleniod.

I added a drawing

[Greg Amy]

You are disconnecting it when the switch is in the off position. With the low current side open when the relay is open there is no flow of electrons past the soleniod.

But, there's low-current power *TO* the switch at all times, so that when the switch is closed, current can (must!) flow. To be able to reset the solenoid from within the cabin, there must be some kind of low-current power to the in-cabin on/off switch - and its associated wires - at all times...

The only way such a remote system could meet the regs is if it were a simple powered, latching relay: as soon as the switch is grounded, all power, including the power to the switching circuit, is disconnected. This would require manually, not electrically, resetting the relay. A latching relay is kinda like a standard mousetrap: self-releasing, but not self-resetting.

Again: I'm not arguing its technical merits. I'm simply saying it apparently does not meet the letter of the regs. - GA

On edit: After reviewing your drawing, Chris, yours does not meet the regs: there is always voltage to those toggle switches, even when the solenoid is de-activated. Unless activating that toggle burns the fuse out - which it cannot, because it would subsequently re-energize the battery circuit - then you still have voltage to that wire, which is running inside the car, and does not meet the requirements of "all" electrical circuits must be cut.

The failure in that design is that it requires constant power in the switching circuit to energize the solenoid thus disconnect the battery. The secondary design failure is that if you lose the switching circuit (wire comes loose, switch fails, wire gets cut in an accident) it fails to a mode where you lose control in a "poor" fashion (i.e., it fails to the "unsafe" condition of not being to disconnect the battery). You can, however, do it slightly differently: instead of a normally closed solenoid, do it with a normally open one, and wire it in series with itself in a "self-latching" fashion. So, when the toggle/button is applied the solenoid de-activates, causing it to open the battery circuit, which de-activates both the battery and the switching circuit. Then, you design a simple method of re-activating it under the hood manually. Right, it's not as convenient as the one you have now, but it's legal and it's safe...

I don't know if anyone would give you grief with what you have (obviously, you got someone local to sign it off). However, were you to ask me to inspect your car for safety, I'd reject that design but offer a recommendation to the Chief Steward to allow it for the event. Then I'd ask you to protest my action and let it run up the food chain until someone farther up made a firm decision on it. You'd get your protest fee back and we'd have a firm answer.

On edit, Part Deaux: On second look, is your solenoid normally open, or normally closed? If it's NO, and you require power to close the battery circuit, that's a "better" design: failure of the switch or its circuit would cause the battery circuit to open. However, it still does not meet the regs, as even in normal operation that toggle switch circuit is always energized, thus does not meet the "all" circuits rule. Further, if that toggle switch wire were to ground out in an accident (pinched at the firewall, for example), the battery circuit would remain charged.

However, this design can be re-engineered into a latching relay circuit, where activation of the toggle switch (or the wire grounding in a crash) opens both the battery and the switching circuit, thus meeting the rules. It would, however, require a manual method of re-activating the solenoid (easy to do, but somewhat inconvenient. - GA

[Rabbit07]

I see your point, but I don't see how it is any different than the power that is always on the B+ side of the traditional master switch? The master switch in this case is the toggle. It just happens to be switch low current power verses high current power.

[Greg Amy]

...I don't see how it is any different than the power that is always on the B+ side of the traditional master switch?

I completely agree with you; it's an issue I've always had problems with...but that's where we devolve into "it's the way it's always been"... - GA

[Rabbit07]

I am going to take a look at the SCCA Pro rules regarding kill switches. That is were I learned about this kind of system and I used it ever since.

[Rabbit07]

APPENDIX G: MASTER ELECTRICAL CUT-OFF SWITCH
G.1: The driver, when seated normally with the safety belts fastened, and the steering wheel in
place, must be able to cut off all the electrical circuits, except the circuit for the fire system, by
means of a spark proof breaker switch. This switch must be located on the dashboard, or center
console, and must be clearly marked by a symbol showing a red spark in a white edged blue triangle.
2008 PRR 140

G.2:

If the master electrical cut-off switch used by the driver is located within 12” of one of the front

door window openings a second electrical cut-off switch is not necessary. Otherwise, a second

cut-off switch must be fitted which must cut all electrical circuits (ignition, fuel pumps, alternator,
lights, battery, etc., but not the fire extinguisher system). It also must be clearly marked by a spark
symbol on a blue triangle. The approved locations for the second switch are; along the A-pillar,
along the B-pillar, or on the windshield cowl. The second electrical cut-off switch shall be located
in close proximity to the second switch/apparatus for the fire extinguishing system.
G.3:

If the car is a formula car, or sports racer, the preferred location for a second cut-off switch

is the right main roll bar tube at approximately driver’s shoulder height.

G.4:

Any exposed electrical contacts on switch shall be covered to prevent sparking.

Says the same thing as the GCR essentially?

Greg, The solenoid is normally open

[Greg Amy]

Says the same thing as the GCR essentially?

I believe so.

Hey, it's quite possible (probable!) that this is not a new issue. It's quite likely that someone has already seen this, questioned it, and gave it an okey dokey. Remember, this is all "but my opinion."

However, to make what I see as the best of both worlds - both safety and strict legality - here's how you, Chris, can mod your existing system:

- First, I'm assuming your solenoid is normally open, where when the switching circuit is NOT energized, the battery circuit is open.
- Next, move the fused circuit that powers the switching side of the solenoid from the battery terminal to the car side of the solenoid (in your drawing, move the fused wire currently attached over the "S" in the word solenoid to the terminal over the "d" in solenoid).
- Bisect that fused circuit, put an appropriate fuse in both wires at the solenoid, and run both wires into the cabin. Attach them to a normally closed momentary push button switch (S1).
- Take the ground side of the switching circuit - where you currently have the toggle switch wired - and connect it directly to ground.
- Add another wire between the "S" and "D" terminals, bisect it with a normally open momentary push button switch (S2), mounted right on top of the solenoid, as close as possible.

So, here's what happens: you just installed the battery, all circuits are dead. To energize the solenoid, pop the hood and push the momentary switch S2. This will energize the switching circuit of the solenoid and close the battery circuit. The solenoid is feeding both the car and its own switching circuit.

In the case of an emergency (or when you park the car in your garage), select S1. This will open the latched switching circuit, de-energizing the solenoid, and killing power to both the car and the switching circuit. Power is isolated to only the battery side of the solenoid (and the battery side of the close-by S2), and nowhere else.

To re-energize the circuit and re-latch the battery isolater, pop the hood and push S2. This will again close the switching circuit and energize the solenoid.

If at any time the switching circuit wiring is compromised by grounding (e.g., wires are crushed in a crash) the fuses in the S1 switching wires will open, causing the switching circuit to open, and de-energizing the solenoid and opening the battery circuit. Any failures in components of the switching circuit (wires, switches, fuses) and the system will fail "safe", de-energizing the solenoid and isolating the battery.

Last and final touch (and this is what I do to address that "hot wire into the cabin" problem): use an appropriate fusible link on the battery positive wire as close as practical to the battery. Any grounding of the battery wire (e.g., at firewall) will cause the fusible link to fail open, disconnecting the battery.

I'm terrible at Internet drawing, but I'd be glad to write it up on the back of a napkin next time we meet... - GA

[Rabbit07]

I believe so.

Hey, it's quite possible (probable!) that this is not a new issue. It's quite likely that someone has already seen this, questioned it, and gave it an okey dokey. Remember, this is all "but my opinion."

However, to make what I see as the best of both worlds - both safety and strict legality - here's how you, Chris, can mod your existing system:

- First, I'm assuming your solenoid is normally open, where when the switching circuit is NOT energized, the battery circuit is open.
- Next, move the fused circuit that powers the switching side of the solenoid from the battery terminal to the car side of the solenoid (in your drawing, move the fused wire currently attached over the "S" in the word solenoid to the terminal over the "d" in solenoid).
- Bisect that fused circuit, put an appropriate fuse in both wires at the solenoid, and run both wires into the cabin. Attach them to a normally closed momentary push button switch (S1).
- Take the ground side of the switching circuit - where you currently have the toggle switch wired - and connect it directly to ground.
- Add another wire between the "S" and "D" terminals, bisect it with a normally open momentary push button switch (S2), mounted right on top of the solenoid, as close as possible.

So, here's what happens: you just installed the battery, all circuits are dead. To energize the solenoid, pop the hood and push the momentary switch S2. This will energize the switching circuit of the solenoid and close the battery circuit. The solenoid is feeding both the car and its own switching circuit.

In the case of an emergency (or when you park the car in your garage), select S1. This will open the latched switching circuit, de-energizing the solenoid, and killing power to both the car and the switching circuit. Power is isolated to only the battery side of the solenoid (and the battery side of the close-by S2), and nowhere else.

To re-energize the circuit and re-latch the battery isolater, pop the hood and push S2. This will again close the switching circuit and energize the solenoid.

If at any time the switching circuit wiring is compromised by grounding (e.g., wires are crushed in a crash) the fuses in the S1 switching wires will open, causing the switching circuit to open, and de-energizing the solenoid and opening the battery circuit. Any failures in components of the switching circuit (wires, switches, fuses) and the system will fail "safe", de-energizing the solenoid and isolating the battery.

Last and final touch (and this is what I do to address that "hot wire into the cabin" problem): use an appropriate fusible link on the battery positive wire as close as practical to the battery. Any grounding of the battery wire (e.g., at firewall) will cause the fusible link to fail open, disconnecting the battery.

I'm terrible at Internet drawing, but I'd be glad to write it up on the back of a napkin next time we meet... - GA

I'll buy you a beer sometime and we can talk about it for hours

[seckerich]

The units we used were a sealed relay contactor system with the relay fed from the hot terminal to the unit. Contactor is normally open and is switched to groung. The output circuit to the switch in the cabin is an isolated circuit with NO CURRENT that just closes a circuit in the relay actuator. The internal circuit is similar to an opto-coupler device. Neat napkin talk though!!

[rsportvolvo]

This thread is hashing out the technical details of the remote kill switch system, which is what I hoped for. I know that these folks are not the local scrutineers, but I don't put a lot of trust/faith/credibility in many scrutineers. I've had run ins with scrutineers for Rolex and SPEED WC and both were in the outfield (Rolex wanted alternative driver safety harness installation that deviated from manufacturer's requirements and SPEED WC approved a cage that didn't have complete, read 360 deg. welded tubes. SPEED WC, required a gusset welded in after they were made aware of the issue, but that was after the car had run several races.). With that in mind I take the Nuclear Power method of "trust, but verify."

I will check with the local scrutineer before heading to the track. I don't like wasting time or money.

Back to the remote switch. What I'm getting is that a remotely actuated switch/relay is safe and legal as long as the remote switch is de-energized. Basically like tripping a breaker. The manual reset of the switch/relay remedies the low voltage remote switch circuit issue Greg Amy astutely pointed out.

This is much better than running B+ battery cable into the cockpit for the driver operated kill switch. There the B+ side is, as Greg Amy pointed out, always hot. Sealed switch in mind a lot can happened to that B+ cable in a crash. Running B+ cable around a car when one could easily (maybe not the cheapest method) install a remote switch/relay is more a luddite move.

All that in mind take a look at the ETA battery isolation switches (offered by Demon Tweeks and can be sourced through IS Motorsport)

http://www.e-t-a.com/uploads/prodb/D_921_922_e_A.pdf

This switch should fit the bill, but I will contact ETA to confirm.

Thanks to all for the input.

[Rabbit07]

I get all the parts for my builds from PRS (248) 844-1060. They are the boys who wire lots of the DP cars and all the Doge Comp Coupes, and some of the Pratt and Miller races cars. The Relay I use is Identical to the part in the Comp Coupe.

The more I think about Gregs point the more I think that we are concerned about two different things.

1. The rules say that all circuits beside the fire system need to be cut. This is the one that doesn't follow the rules.

2 There is a circuit with power flowing to it into the cabin. This is not different than the traditional switch being run into the cabin. That is allowed in the rules.

Because the circuit that is run into the cabin is through the "load" first there really isn't any power flow to the switch. If you were to check for 12 volts at the back side of the relay were the circuit flows to the toggles you would not find 12 volts due to it being used up to close the relay contacts. Ther only time that there would be voltage there is when the circuit is open or there is high resistance in the circuit causing a voltage drop.