Landracing Forum
Tech Information => Safety => Topic started by: Slide on August 03, 2016, 01:23:35 PM
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Hey guys,
My rule book is with my car which is at the cage builders. The cage builder is out racing and wont be back for two weeks. I am trying to get a battery kill switch set up for the drivers compartment.
I am looking at the following type of cut off. I like the button idea as it is different than the pull switch for the fire system. I believe that the pull switch and the regular red turn key look too similar and may get in each others way if I am going for one and not the other or some such nonsense.
Remote Disconnect w/Emergency Button
http://www.painlessperformance.com/webcat/30205
(http://www.painlessperformance.com/webcatalog/plarge/30205.jpg)
The car will "hopefully" run in one of the upcoming mojave miles and mile and a halfs... and then in a shift sector airstrip attack half mile...and maybe a texas mile if timing all works out.
But the car is really not, actually its not built to be competitive in any class, I have just built it, or rather building it, for fun with parts that I want...(which puts it into all sorts of screwy classes if I were to get to technical!)
Anyways, can anyone see a reason, that if I were to be in the 200 to 205 mph arena, be stopped at the inspection phase for this type of cut off? The button is what I think makes it not nhra approved vs a key style switch....
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At least for SCTA events, the switch is mounted outside where it can be accessed by safety personal in case of an accident in which you are disabled. For other organizations the rule may be different.
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I was planning on justo side the window. So reachable by driver and safety personnel.
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Has to be on the front or rear of vehicle.
If you have a "one wire" alternator this won't kill the engine as the alternator will feed the system with the battery disconnected.
Sid.
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Slide:
I like that set up looks like it could be installed in a neat and clean way. To satisfy the rules. I built a push off knob at the left rear and then used a teleflex throttle cable to connect a linkage to a handle and knob in the driver's compartment. I use all relays and do not have any high amp circuits inside the driver's compartment. The parachute handles pull to the rear while the in-car master electric cut off pushes forward. Other than the mounts, I fabricated a new lever for the battery on/off switch so it is pretty easy to make. I started to make cutoff from an electric door lock actuator but then decided against electric and used a linkage. I did not want a blown fuse in the electric cut off to prevent me from cutting all power from inside the car. I figured once the car starts rolling over it is plausible that damaged electrical connections could ground and start popping fuses.
I am a backyard non-professional fabricator so this is just my 2 cents.
Good luck with the build.
BR
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Wheelrdealer and kiwi belly tank: Thanks for the info guys I appreciate it! We have an idea on where we need the electrical break to be, we just aren't sure if any of the ruling bodies would have a problem with the push button style.
I plan on having a second switch, more than likely a standard key shape, that is directly in line so there is a back up. But for the one that is driver accessible (and potentially the one that satisfies the safety worker accessible in the same part) I'd like and am willing to have a remote switch to.
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You can do whatever you want on the driver cut off. The safety requirement wants a clearly marked outside switch or push button. Usually on the left rear somewhere. You need to look at the rule book again.
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Thanks. Rule book is still with cage builder....
Ordered the cartek xs so I can run push buttons and kill battery as well as ecu with out issue.
Little pricey but light and does the job. No parts to get stuck or break....I hope.
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Thank you for your advices! There are very useful!
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Slide;
My battery cut-off switch is a Moroso rotary knob on/off switch mounted to the chassis. I replaced the knob with a lever arm that is connected to a push-pull cable that comes out the front, on the side of my radiator air intake. Also connected to that lever is a short rod that comes into the cockpit through a support bushing. A round knob on the end of the rod also allows the battery to be switched on/off by the driver.
In addition to the battery cut-off switch, I have a very high current relay that supplies power to everything but the starter motor. A toggle switch with a spring-loaded red cover is mounted on the instrument panel, allowing the driver to quickly shut off power with a swipe of a gloved hand. There is a G-switch in series with the relay coil so an impact will also shut off the 12V DC power.
Regards, Neil Tucson, AZ
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As Neil suggests, at least for SCTA and ECTA (you need to check rules for the other organizations) you need an inertia type cut off switch for an electric fuel pump, regardless of other battery cut off switches. In a prior car I had a Moroso type switch for the driver as well as one outside to meet the safety requirements. I think this is at least in part what you are asking. Stuff may happen suddenly so you might not have time to shut things down.
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We have a cutoff at back of car,rollover for fuel pump and one within reach of driver. WE are into safety. Cheap investment.
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A relay/solenoid electrical cutoff is nice because it allows any number disconnects
to me located wherever you like them. A single lead being grounded triggers
the solenoid to then power the car. That lead can go thru a NC switch for the safety
crew, NC shock/rollover sensor and finally to the drivers master switch.
The trick is to isolate the ignition from the alternator. To do so use two relays
mounted side by side next to the battery, both triggered by the same ground signal.
The first is of the high amp variety like the one pictured above. Its output feeds
the starter solenoid. The alternators output is also connected to the starter solenoid
feed. This is the path used to charge the battery.
The second is a typical 40 amp relay that feeds the ignition system and/or fusebox.
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The problem using a ground switch to a relay is if that circuit rubs a short to ground you now can't shut it off. If you switch the power side & you have a short it pops the fuse & shuts it off.
Easiest way with the charging system is don't use a one wire self exciting alternator, use a field excited alternator so when you kill the battery you kill the alternator.
Sid.
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If concerned about a fault rubbing the circuit and keeping everything on, it is just as easy to trigger the
relays high-side instead as low-side. You just run the fused loop thru the switches and permanently ground
the opposite terminal.
Alternators that will keep the engine running are not limited to the single wire variety. Two wire Bosch, Delco
and Nippondenso (Denso) units that I've worked with won't. Only some of the newer style systems with
separate switched power and sense wires can recognize the battery disconnect and shut down. So don't
assume, test. And test at a decent RPM. I've seen cars pass the battery cutoff test at idle due to low alternator
output (underdrive) but continue to run when RPMs are elevated.
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Slide;
My battery cut-off switch is a Moroso rotary knob on/off switch mounted to the chassis. I replaced the knob with a lever arm that is connected to a push-pull cable that comes out the front, on the side of my radiator air intake. Also connected to that lever is a short rod that comes into the cockpit through a support bushing. A round knob on the end of the rod also allows the battery to be switched on/off by the driver.
In addition to the battery cut-off switch, I have a very high current relay that supplies power to everything but the starter motor. A toggle switch with a spring-loaded red cover is mounted on the instrument panel, allowing the driver to quickly shut off power with a swipe of a gloved hand. There is a G-switch in series with the relay coil so an impact will also shut off the 12V DC power.
Regards, Neil Tucson, AZ
Neil, what inertia/G switch manufacturer are you using? I had a stock Ford inertia switch in my lakester for WoS and it shut off three times during one run. Obviously, I will not use a Ford switch next time but am having trouble sourcing a better alternative.
John
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John, We have always used a Ford switch in the Bockscar, never had a problem and only $5 at pick&pull. We used the ford bracket to mount it in the tail of the lakester. :cheers:
The switch only cut the power to the fuel pump relay.
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We had horrible luck with ford cut off switches in our agencies crown Vic’s... no rhyme or reason, but some cars were super sensitive...others not so much.
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John, We have always used a Ford switch in the Bockscar, never had a problem and only $5 at pick&pull. We used the ford bracket to mount it in the tail of the lakester. :cheers:
The switch only cut the power to the fuel pump relay.
John, you were there and witnessed first hand the trouble we had with that Ford switch. There has to be a better, higher G switch out there. Tom Burkland mentioned Riekers (sp) as a possible manufacturer of an adjustable G switch that also had a tilt feature but I can not find them anywhere on a net search.
John
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From what I've heard, sounds to me that the trouble is not the switch but the track roughness.
Ron
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From what I've heard, sounds to me that the trouble is not the switch but the track roughness.
Ron
Ron, the three mile short course was rough but not so bad as to trip an inertia switch. Maybe I was the only one having this problem or I just had an overly sensitive switch. Either way, I want something better for next year. Conditions at Bonneville are not getting any better so our new reality is a rougher track and vastly different surface conditions. Just trying to get the car ready for whatever the track gives us.
John
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I've got a small bucket of Ford switches. By hitting them against my palm, the only way I can get them to trip is longitudinaly (sp). Vertical seems to have no effect. Then again I am going from memory and that ain't near what it used to be. Going to the shop to test memory. :-D
Ron
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UPDATE PLEASE--
I read this and was wondering if anyone had any more current experience with inertia switches?
I also have had problems with the Ford systems we are going to run an electric pump this year.
Sparky
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I run a Ford inertia switch- no problems with it.
Ron- Slamming it against your palm may not generate the 20Gs necessary to trip it. Try banging it on the floor. The switch is a pair of v-shaped contacts with a metal ball resting on them. The switch will actuate in all directions except the one that drives the ball harder into the contacts.